NEURO #1 - Intro, Semiology & Cranial Nerves Exam PDF

Pag. 1 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves NEURO #1 – 12/03/24 Introductions to the course Sem...

Pag. 1 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves NEURO #1 – 12/03/24 Introductions to the course Semiology Examination of cranial nerves Prof. Nobile – 01/10/24 – Author: Sohayla Zayan Introduction to the course The professor began the lecture by introducing the course, outlining how it will be conducted, and explaining the exam format, including the asynchronous activity. Details in italics are from last year's notes, which the professor did not mention. These may help address any gaps or questions you have, especially regarding the graded asynchronous activity. However, I cannot guarantee that these details will apply to us. The course, “Neurobiology, human behaviour and clinical neuroscience” is big, and it is made up of 19 CFU (frontal) + 2 CFU (clerkship). We will have lessons on many specialties with the main leading topics being Neurology and Mental Health, the only two of which we will have the oral examinations. Then we will have lessons on Neurosurgery that has only 1 CFU, Rehabilitation Medicine (1CFU), Infant Neuropsychiatry (1CFU), Pathology (1CFU), Radiology (1CFU), Pharmacology (1CFU), Human Physiology (1CFU), Anatomy (1CFU), General Psychology (1CFU), Clinical Psychology (1CFU). There will be frontal lectures and asynchronous activities that we have to do by ourselves. Each teacher will have his own modality. Prof. Martinelli Boneschi will ask us to write a report. The asynchronous activities of Nobile-Orazio consists in preparing a clinical case on each topic he will deal with in his 6 lectures, that are: stroke, dementia, epilepsy, infectious diseases, neuromuscular diseases and headache (the past notes say they are 8). We will have to report the case in a story form, starting from their presentation and their symptoms, including our hypothesis, the examinations we would perform and the therapy we would order. These are to be sent to his email that is: [email protected]. If we do not do it, we will not be allowed to take the exam, it is a mandatory activity. He will review all 6 clinical cases written by each student and give us feedback by email. At the end the prof will give us a score based on the quality of our work. It can be 0 if it is fine, +1 if it’s good, +2 if it’s excellent. This will be added to the grade we get in the neurology exam, if you write excellent reports and your grade in Neurology is a 28, you will get a 30. The past notes precise that he can also give negative scores if not done properly: The final score can range from +2 to -2 points.  Pag. 2 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves We can submit them individually or in groups, but we are not allowed to send them just a week before the exam. They must be submitted at least two weeks before the exam, as the professor needs time to review and provide feedback. Then, he will ask us to write an essay on how to perform a neurological examination starting from the beginning to the end 🡪 Not mentioned in class. Regarding the clerkships, we will attend 1 week of clerkship in the Neurology department and 1 week in the Mental Health department. Secretary will give us more information. Remember that we need to have 67% of attendance to have access to the exam. Do not put the code if you are not in class because he will check the number of students actually in class. Here is the list of books suggested by all the professors; Professor Nobile said the first one is really good. What is important and he wants us to know are the most important neurological diseases. He will never ask us strange, rare diseases/syndromes like some weird genetic epilepsy, these are things you will deal with in the residency. What is important is that we understand how to recognise a patient with a neurological disease, the signs and symptoms caused by a neurological disease, what is a neurological disease, and whether the patient needs to be admitted or not to the hospital or can be managed in the outpatient clinic. About the examination procedure: student assessment is based on a combination of written and oral examinations. The written test and oral examination will cover all the arguments covered by the seminars. The written exam is a multiple choice test focused on the topics of all modules but Neurology, Mental Health and Clinical Psychology. The test for Clinical Psychology will consist of a separate open written essay that will be evaluated as positive or negative. Students who successfully pass the written test for all the disciplines and the written essay are allowed to take the oral examination of Neurology and Mental Health. Students may also access the oral examination if they fail to pass one discipline as far as at least 40% of the responses were correct in that discipline or if they pass at least 80% of all proposed tests. A passed written examination remains valid for the academic year. Asynchronous activity will receive +/-0-2 score based on the quality that will be summed to the oral score of the discipline There are 5 questions for each subject. We need to get at least 3 out of 5 (60%) correct to pass the subject. There is the possibility that if you get 2 out of 5 in one subject but in all the others you get 4 or 5 out of 5, you will pass the exam. If the overall count of the test is 80% you can pass the test.  Pag. 3 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves The final mark is the weighted average of the marks obtained at the oral examinations based on the credits of the two disciplines. The oral examination of Neurology (5 Credits) and Mental Health (4 Credits) can be passed separately and the score remain valid for the academic year He recommends doing them separately because it is difficult to give the exam as a whole. _______________________________________ In the past year notes there were indications regarding the anatomy and physiology parts too: We will have a total of 6 lessons of anatomy, coupled then with lessons of physiology. For the asynchronous activity there will be a test that is mandatory. There will be an opening date hour and a closing date and hour. Pay attention to the due dates because she will not make exceptions. The questions on anatomy and physiology of the written exam will be very basic and on what the professors explain in class, what is written on the slides. Most of the questions are always the same but they can change a bit. The lectures of anatomy and physiology are paired: we will have lessons of the basics of anatomy that are needed to address the functional issues. We will mainly focus on the topics dealt in second year to take the best of them. The topics will be mostly concentrated on the neocortex, so the associative areas and high cognitive functions; the emotions and which are the neural circuits involved; the extended limbic system meaning the central part of the vegetative system; motor cognition and sense of agency; the functional organization of the white matter. For physiology we will have frontal lectures on the associative cortices and so high cognitive brain functions, the emotions and the functional organization of the brainstem. Differently from physiology, Sforza seems to say we will have an asynchronous and not a frontal lecture on the latter topic (functional organization of the brainstem). The brainstem is the first thing we assess in the ER. When you have a patient in front of you, the first thing you do is to assess the brainstem as it hosts the vital centers (ocular movements, for example, are windows of the brainstem). Prof Cerri will give us assignments on the functional organization of the white matter, motor cognition and sense of agency because we already addressed the motor system thoroughly in second year. In the next few days, we will discuss the higher-level functions, the emotions and the brainstem together. The assignments are mandatory so if we do not do them, it's like not being in class so it counts on the attendance. They are part of the program that can be asked at the exam. It is just another way to teach. Check the syllabus that has been updated on Ariel.  Pag. 4 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves Semiology I. General information about neurology Neurology focuses on diseases affecting the central and peripheral nervous systems, as well as the muscles. Historically, neurology and psychiatry were studied together since psychiatric conditions also originate in the brain. Neurology, however, is more closely associated with structural brain disorders, such as tumors, trauma, inflammation, or malformations. While structural lesions are often visible, in some cases, like Alzheimer’s disease, one might observe only brain atrophy. Neurological diseases always involve some form of structural, biochemical, or genetic damage to the brain. The field of mental health is increasingly overlapping with neurology, as research shows that many psychiatric disorders are associated with underlying pathological changes. These changes may not always be visible but can include biochemical or genetic abnormalities. For instance, some psychiatric disorders, like bipolar disorder or depression, have genetic components—meaning that a family history, such as a parent with depression, can increase the likelihood of experiencing similar conditions. Despite these overlaps, neurology and psychiatry remain distinct disciplines. Psychiatry often takes a symptomatic approach, focusing on treatments that address the symptoms directly. For example, in treating depression, it is known that serotonin levels are low, so therapy aims to increase serotonin through medication. The professor frequently emphasizes the saying: "Neurology is the study of brain diseases, while psychiatry is the study of mind diseases." Both involve the brain, but neurology deals more with structural aspects. In neurology, the central nervous system (CNS) includes the brain, cerebellum, brainstem, and spinal cord. From the CNS, nerve roots extend to form plexuses, which eventually give rise to peripheral nerves that reach different parts of the body, thus forming the peripheral nervous system (PNS). There are distinct structural differences between the CNS and PNS. For example, in the motor system, the pyramidal pathway, a motor pathway, extends to the spinal cord, where it connects with the lower motor neuron that sends signals to the muscles. When exiting the CNS, the pathway enters the PNS, although the neuron cell body remains within the CNS. A key difference lies in the myelin sheath composition: in the CNS, myelin is produced by oligodendrocytes, while in the PNS, it is produced by Schwann cells. Therefore, diseases affecting myelin in the CNS differ from those affecting the PNS. The nervous system is responsible for controlling all movements. Motor signals travel down the spinal cord to motor neurons (represented as red in the diagram below), which innervate muscles to produce movement. Sensory information from receptors in the skin, eyes, or other organs travels back to the CNS (represented as green and blue in the diagram). The CNS functions like a central computer, while the PNS acts as a network that extends to the body's periphery. The PNS is crucial because if it becomes damaged, as in the case of Guillain-Barré syndrome—a type of acute neuropathy—the brain may still function properly, but the connection to the periphery is disrupted. This results in a lack of communication between the brain and the muscles, as well as a failure to relay information from the periphery back to the brain. Therefore, the integrity of the entire nervous system is essential for proper functioning.  Pag. 5 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves II. Main categories of neurological diseases These are the main categories of neurological diseases that we will cover: Cerebrovascular diseases (like stroke) Trauma 🡪 it will be mostly done by the neurosurgeon Neoplastic diseases 🡪 they will be mainly covered by pathologists and neurosurgeons Epilepsy Headache 🡪 it is a strange disorder because in most types of headache we do not see any structural damage, we know there is something, but we do not see it. It is one of the most frequent conditions. We will have a seminar on it. Infectious diseases 🡪 they will be covered by the prof. himself, like meningitis, encephalitis… Inflammatory diseases 🡪 we will mostly focus on multiple sclerosis Degenerative neurological disorders 🡪 they will be covered by prof Silani and we will talk mainly about dementia, Parkinson’s Disease and ALS. These are not curable but symptoms can be treated. Developmental diseases 🡪 they will be covered mainly by neuropsychiatrists Spinal cord diseases Peripheral nerve diseases Muscle and neuromuscular diseases This report, published a few years ago by MacDonald, presents the lifetime prevalence of common neurological diagnoses per 1,000 people. Stroke, or cerebrovascular accident, is the most frequent, with a prevalence of 10 per 1,000 people (1 in 100). For example, in a population of 50 million, this ratio means that approximately 500,000 people will experience a stroke. It is important to note that not all patients experience a full stroke; some may suffer from transient ischemic attacks (TIAs). Epilepsy is also a common neurological disorder, followed by Parkinson’s disease and multiple sclerosis. 6% of the population had a neurological disorder sometime during their lives, which is 3.6 million people in Italy as we are almost 60 million people.  Pag. 6 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves 625 neurological disorders were observed per 100 000 people annually, which is about 360 000 people (actually 375 000) in Italy. In the context of emergency room visits, 20-30% of patients present with a neurological issue. These can include conditions like vertigo, stroke, epilepsy, trauma, weakness, motor dysfunction, severe headaches, and others. These disorders are fairly common, highlighting the importance of having a basic understanding of neurology. While some may view neurology as overly complex, the professor emphasizes that the goal is not for us to make diagnoses but to understand the nature of neurological diseases, assess their severity, and recognize when a patient may have a neurological issue. A common challenge among physicians is distinguishing whether a patient's problem is neurological, psychological, or functional. When symptoms are difficult to interpret, making a diagnosis can be challenging. It is only appropriate to consider a functional disorder when tests have ruled out organic causes. There have been instances where patients were sent home undiagnosed, only to later discover a serious issue. Therefore, it's crucial to take the patient's account seriously, listen carefully, and try to piece everything together. Even if you don't fully understand a particular neurological condition, neurologists are available for specialized care. Today's medical practice is highly specialized, with no single physician covering all disciplines. Within neurology itself, there are sub-specializations: some neurologists focus on cerebrovascular diseases like stroke and hemorrhage, while others specialize in neurodegenerative diseases, neurological infections, or peripheral neuromuscular disorders, among other areas.  Pag. 7 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves III. Instrument for neurological examination For a neurological examination, only a few essential tools are needed: Hammer: Used for testing reflexes. Diapason (tuning fork, instrument on the far right): Measures hearing and vibration, providing an assessment of deep sensation. It is used by placing it on a bone, allowing vibration transmission to give insight into the patient’s deep sensation. Cotton bud: Useful for testing a patient’s light touch sensation. It can also be broken in half and used as a makeshift needle to check for pain response. Ophthalmoscope (third instrument from the left): Allows examination of the eye's fundus to check for papilledema, which can indicate brain hypertension. Detecting edema around the optic disc is a sign of increased intracranial pressure. While this was especially critical in the past, today patients in the ER are often sent directly for a CT scan, which provides results within 5 minutes. IV. Initial approach to neurological patients When evaluating a patient who might have a neurological problem, the first and most crucial step is to observe the patient. Sometimes, just by observing the patient you can make a diagnosis. Look at how he walks, if he can walk independently, if he needs support, if he has a particular gait like in Parkinson's disease where you can make a diagnosis just based on how the patient walks. Observe the patient and how he moves. If, for example, in an exam setting, you are asked, "A patient comes to you with vision problems, what do you do?" A common mistake is to say, "I start examining the patient." Instead, the correct approach is to first observe the patient, engage in conversation, and ask about their symptoms, focusing on what they describe. Look at the age and the apparent general condition, if he is cachectic, if he looks healthy, if he is thin, if he lost weight. Observe if he is alone or accompanied by another person. Observe if he is wakeful, alert, if he responds. Observe if the patient has any unusual posture or movements like tremors. The reports from NEJM (New England Journal of Medicine) are exemplary because they begin with the patient's symptoms, providing a clear reason why the patient sought medical attention. For example, a report might state that "the patient has weakness on the right side of the body." Once you have an idea of the symptom or issue, you can proceed with taking the patient’s history. The main point is to ask to the patient what is the problem bringing him to the visit. Ask when the story started. If it started 10 years ago, it is a chronic problem, if it started a few days ago, it is an acute problem, if it started a few months ago, it could be a subacute problem. Apart from the duration, we should ask about the progression of symptoms: if they have been progressively worsening or just relapsing or stable in time. Then you should also consider if there are any other associated symptoms  Pag. 8 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves The questions you ask should be targeted based on your understanding of the possible condition. For instance, if a patient presents with trauma after a car accident, it’s more relevant to focus on the trauma rather than a family history of conditions like Alzheimer's. The history should be specific to the patient's current situation. When a patient presents with vision problems, it’s essential to ask specific questions like: When did the problem start? What exactly is the problem? Are they unable to see out of one eye? Are they experiencing double vision? Is their vision blurry or unclear? Is the issue present in one eye or both? This helps narrow down the nature of the problem, and. If the patient says he has difficulty in moving his hand and weakness in his hand, it could be a problem of the muscles or the nerves or maybe a stroke, so ask him if he has problems also in moving his leg, in his face. Check also if the problem is just motor or also sensory: is the problem that you no longer have strength in the muscle or have you also lost the sensation? Then you can ask other questions: - Does the patient suffer from other diseases? Did he have diseases or surgery? - What drugs is the patient taking? - Is the patient under chemotherapy? This could be the cause of the tingling sensation in his finger. - Is he taking any potentially toxic agents? - Does the patient smoke? Does the patient drink alcohol? - Are there any neurological and non-neurological diseases in the relatives? Sometimes neuropathies have family history that can help you in making the diagnosis. - What is the sexual attitude of the patient? - What is the patient’s job? - What is the patient’s mood? - Did the patient undergo previous tests, visits or diagnoses? Always begin with the patient's symptoms. Before considering a neurological problem, assess whether the symptoms align with a potential neurological disorder. Sometimes, a patient might present with a story that seems unlikely—for example, tingling in the hand, pain in the back, or pain in the gluteal area. This is where understanding anatomy becomes crucial. You need to consider where in the central or peripheral nervous system, or even in the muscles, the issue might be that could explain these symptoms. For example, if a patient has double vision, the underlying problem could be due to a palsy—meaning a deficit in the movement of one eye. This could result from issues with the nerve that sends signals to the eye muscles, a problem with the ocular muscles themselves, or an issue at the neuromuscular junction (NMJ), such as in Myasthenia gravis, where impaired signal transmission from the nerve to the muscle can cause double vision. Alternatively, it could involve a problem with the nerve within the subarachnoid space or even the nerve nucleus located in the brainstem. Thus, a symptom like double vision could stem from a muscle issue all the way to a brainstem problem. When encountering any symptom, always think about the anatomy: consider what the problem might be and where it could be located (muscle, NMJ, nerve, brainstem). So, the neurological examination begins by assessing the patient's presentation, including their level of alertness and ability to respond to questions. It is important to conduct the exam on a patient who is alert and able to follow instructions. The examination proceeds in a systematic manner, starting from the top and moving down: The exam begins with evaluating the 12 cranial nerves. Next, the motor system is assessed, checking for strength, movement, and any abnormalities. This is followed by an evaluation of the sensory system to understand the patient's perception of touch, pain, temperature, and proprioception. The function of the cerebellum, which coordinates movement and balance, is then tested. Lastly, the patient's cognitive functions are assessed, primarily focusing on their level of alertness and awareness.  Pag. 9 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves Examination of cranial nerves I. Cranial nerves summary The cranial nerve examination is often the simplest to perform, making it a logical starting point for the overall neurological assessment There are 12 cranial nerves, all part of the peripheral nervous system (PNS) except for the optic nerve (CN II). The optic nerve is composed of myelin and nerve tissue typical of the central nervous system (CNS), which is why it is particularly affected by CNS diseases like multiple sclerosis. Let's go through the cranial nerves in order: 1. Olfactory (CN I): the cranial-most, responsible for the sense of smell; it originates in the brain. 2. Optic (CN II): Carries visual information from the eyes to the brain; it is technically part of the CNS due to its myelin structure. 3. Oculomotor (CN III): Controls most eye movements, pupil constriction, and maintains an open eyelid. 4. Trochlear (CN IV): medially, controls the superior oblique muscle, enabling downward and inward eye movement. 5. Trigeminal (CN V): laterally, mainly sensory, responsible for sensation in the face and motor functions like biting and chewing. 6. Abducens (CN VI): Controls the lateral rectus muscle, allowing the eye to move outward. 7. Facial (CN VII): Primarily motor, it controls facial expression muscles, as well as functions related to salivation and lacrimation (tear production). 8. Vestibulocochlear (CN VIII): Related to hearing (cochlear) and balance (vestibular). 9. Glossopharyngeal (CN IX): Involved in taste, sensation, and movement in the oropharynx and back of the tongue. 10. Vagus (CN X): Regulates many parasympathetic activities, including most of the gastrointestinal (GI) tract motility and heart rate. 11. Accessory (CN XI): Controls the sternocleidomastoid and trapezius muscles, which are involved in neck movements. 12. Hypoglossal (CN XII): Controls tongue movements. The cranial nerves are organized from the top down: the olfactory nerve (CN I) originates from the brain, while the others emerge progressively lower—from the midbrain, then the pons, and finally from the medulla..  Pag. 10 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves  Pag. 11 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves II. Olfactory nerve (I CN) 1. Anatomy and physiology of the I CN The Olfactory nerve (CN I) is responsible for the sense of smell. Here’s a brief overview of its anatomy: - The olfactory epithelium is located at the roof of the nasal cavity and contains receptors that detect odors. These receptors transmit the sensory information through the olfactory nerve filaments to the olfactory bulb, which is part of the brain (CNS). - The olfactory bulb processes this information and then sends it mainly to the olfactory cortex, but also to other diffuse brain areas, integrating smell with memory, emotions, and cognition. The olfactory nerve is essential not only for humans but especially for animals. For example, animals rely on their sense of smell to find food and to recognize others, as seen in dogs, who use their olfactory sense to identify familiar individuals. For humans, certain smells can trigger visceral reactions, like disgust when encountering a foul odor. This strong connection between smell, emotions, and cognitive functions is also key in animals, aiding in social interactions such as mating behavior. The diagram below illustrates the main structures involved in the olfactory pathway: the olfactory receptors located in the nasal cavity, the nerve filaments (fibers), the glomerulus, and the olfactory bulb where these signals are processed. 2. Symptoms and causes Symptoms that indicate a problem with the olfactory nerve (CN I) include: Anosmia: The complete loss of the sense of smell. Hyposmia: A reduced ability to smell, where the sense of smell is diminished but not entirely absent. Dysosmia: An altered perception of smell, where a person detects a different smell than what is actually present. This includes smelling something inaccurately or in a distorted way. Cacosmia: A specific type of dysosmia where the person perceives a bad or unpleasant odor. This symptom is particularly significant because it can precede certain types of epileptic seizures, especially temporal lobe epilepsy. Cacosmia may act as a warning sign before a seizure or a loss of consciousness, making it an important symptom to recognize in neurological assessments.  Pag. 12 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves Anosmia, the absence of the sense of smell, can present in various forms, including temporary, permanent, progressive, or congenital. Temporary Anosmia is most commonly caused by infections, such as the common cold, flu, or during COVID-19. Other infections, like meningitis, can also cause temporary anosmia. Local nasal disorders, such as allergic rhinitis, can lead to temporary anosmia as well. Permanent Anosmia’s Causes include head injuries, brain tumors that compress the olfactory nerve (e.g., frontal meningiomas, Foster-Kennedy S.) or chronic basilar meningitis. Progressive anosmia can be the result of neurodegenerative diseases like Parkinson’s disease and Alzheimer’s disease. This is a sign of the degeneration of the nerves and often precedes other symptoms, though patients may not immediately notice the loss of smell. Other factors include aging, smoking and cocaine use. Anosmia is also a feature of genetic conditions such as Kallmann syndrome (associated with puberty failure) and primary ciliary dyskinesia (defective, immobile cilia). 3. Testing the I CN The olfactory nerve (CN I) is not commonly tested during a routine neurological exam. However, when it is tested, it’s essential to use a substance that is non-irritating to the nasal mucosa, such as coffee. The test involves asking the patient to close their eyes, then presenting them with a scent, and asking them to identify it. There are certain situations where testing the sense of smell becomes important, particularly in traumatic or neurosurgical cases. For example, in the event of a head trauma, there may be damage to the cribriform plate, which houses the fibers that connect to the olfactory bulb. Trauma to this area can cause shearing and breaking of these fibers, leading to a loss of smell (anosmia). Therefore, after a trauma, it’s standard to ask the patient if they can still smell to check for potential fractures or damage. Although a CT scan is often used to assess such injuries, it may not always reveal the presence of small lesions or shearing of olfactory fibers. Thus, checking for changes in smell can provide additional clues about possible damage. A CSF leak can be a serious complication following trauma or neurosurgery, particularly in procedures involving the frontal lobe. This condition requires prompt identification and treatment due to the significant risks it poses, including a higher likelihood of infections like recurrent meningitis. When CSF leaks, it creates a potential pathway for bacteria to enter the space surrounding the brain and spinal cord, increasing the risk of infections. Since CSF serves to protect and cushion the brain and spinal cord, any breach in its containment can make these critical structures more vulnerable to external pathogens. Patients with a CSF leak often present with continuous nasal drainage, describing it as a clear fluid that persists even without symptoms of a cold or flu. A typical complaint might be, “I don’t have the flu or a cold, but my nose is continuously leaking.” This persistent, unexplained nasal discharge can be a key indicator that further investigation is necessary to distinguish between nasal secretions and CSF. A glucose test is the primary method used to differentiate CSF from normal nasal secretions. Normal nasal secretions generally have low glucose levels, whereas CSF contains glucose in concentrations similar to those found in the blood. To perform the test, a sample of the nasal fluid is collected in a vial, and a glucose test strip is used. If the glucose concentration is found to be above 40% of the patient's blood glucose level, the fluid is likely CSF rather than simple nasal mucus. Once a CSF leak is confirmed, it becomes crucial to locate the source of the leak. Treatment involves surgical intervention to seal the breach, which helps to prevent ongoing leakage and the associated risk of infections.  Pag. 13 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves III. Optic nerve (II CN) One of the main presentations we need to understand is that of a patient who comes to the hospital with a visual disturbance. Typically, these patients report that they do not see well, and our task is to determine the underlying reason for this issue. 1. First, we need to assess whether the patient is experiencing a loss of visual acuity, which can occur with age. This age-related loss is usually a gradual process. However, there can also be more acute onset conditions, such as glaucoma, which results in loss of visual acuity due to abnormal transmission of the visual impulse from the cornea to the optic nerve. We typically evaluate visual acuity using the Snellen chart and may also use a funduscope to further assess vision. 2. Another potential issue is loss of visual field, which is commonly associated with diseases affecting the optic nerve or the brain. For instance, a patient may report not being able to see half of their visual field. This does not necessarily mean they are completely blind in that eye; they might have full vision in one eye but some issues in the other, or they could be experiencing a similar deficit in both eyes. For example, a patient might say, “I can’t see from this eye because I can't see the right side of the field.” However, upon closing that eye, they may still report, “I still can’t see from the other eye,” indicating they have what we refer to as hemianopsia. 3. Additionally, a loss of visual alignment can result in diplopia, or double vision. A patient may wake up seeing two images of an object side by side. This occurs because the eyes must move in tandem to align visual information in a congruent area in both eyes, allowing the brain to perceive a single image. To effectively assess the situation, it is important to ask the patient specific questions upon their arrival. We should inquire: “When did this happen?” “Has this been progressing for days, weeks, or did you just wake up this morning with this problem?” “What kind of visual disturbance are you experiencing? Is it that you can’t see from one eye, are you experiencing peripheral vision loss, or are you seeing double?” “Do you have any pain in your eyes?” Most patients with neurological problems also present with visual disturbances, especially those experiencing diplopia. When patients encounter eye issues, they often visit an ophthalmologist, who may then refer them to a neurologist, stating, “This is not my area; it’s a problem related to the nerve, not the cornea.” 1. Loss of visual acuity Loss of visual acuity typically relates to issues with the ocular bulb, cataracts, or problems with the cornea or lens. Patients experiencing this kind of visual disturbance usually visit an ophthalmologist, who can often provide corrective measures. However, it is important to note that inflammation of the optic nerve can also lead to vision loss, and the presentation of this vision loss differs from that caused by corneal, lens, or ocular bulb issues. 2. Loss of visual field a. Review of visual pathway To understand the optic system, it's essential to remember that visual information is always crossed: what occurs in the right visual field is processed in the left hemisphere, and vice versa. This crossing mechanism is also observed in the motor and sensory systems. We can visualize a central field that both eyes perceive. However, there are instances when vision in half of the visual field is lost. How does this happen?  Pag. 14 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves The image below illustrates the visual field. The central part is seen by both eyes, and each eye receives visual information that is crossed. When light enters the eyes, it passes through the lens and lands on the retina. Images coming from the nasal visual field reach the lateral half of the retina in the right eye (temporal retina) and the medial part of the left eye. Essentially, the medial visual field projects onto the temporal retina of both eyes. For the right eye, the medial visual field—represented in red and purple—lands on the temporal retina (the lateral part of the right eye). In contrast, the temporal visual fields for the left eye are also represented in red and purple, landing on the medial retina (the inner part of the left eye). Referring to the “projection on the left retina” in the image, we see that the left eye’s retina captures this larger area (red-purple) because it is not obstructed by the nose. This same region (red-purple) is seen by the right eye, but only in the temporal aspect—illustrated as “projection on the right retina.” Conversely, the yellow-green area represents the opposite visual field. The visual stimulus travels along the optic nerve, and upon reaching the optic chiasm, the fibers from the medial part of the retina cross over. These fibers join those carrying information from the same area of the visual field from the other eye. In simpler terms, the fibers carrying the medial visual field of one eye and the fibers carrying the temporal visual field of the other eye—representing the same image—remain on the same side of the chiasm. For instance, the green and yellow field represents the medial visual field of the left eye, which also corresponds to the temporal visual field of the right eye. At the chiasm, both sets of fibers stay on the same side. When we examine the image below, we can see that the fibers carrying information from the medial retina always cross, while those from the temporal retinas do not. For example, the nasal retina of the right eye gathers information from the lateral side of the visual field. The fibers from the nasal retina of the right eye cross over to the left side, joining the fibers from the temporal retina of the left eye that also receive information from the same visual area (the yellow-green area). After the optic chiasm, where the crossing of fibers occurs, all visual information from the contralateral side can be processed. If there is a lesion occurring after this crossing point, loss of half of the visual field can occur. This condition is known as hemianopsia, which refers to the loss of vision in half of the visual field. Optic pathways  Pag. 15 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves b. Testing peripheral vision Understanding the anatomy of the visual system is crucial for effectively conducting a neurological examination. During the examination, we instruct the patient to fixate on our nose and to avoid moving their eyes. The examiner then moves their hands, making small movements, while the patient must indicate whether they can see these movements without shifting their gaze. This process tests peripheral vision. Another method for assessing peripheral vision involves examining both the central and peripheral visual fields. We ask the patient to close one eye and then check what they can perceive in their visual field. When performing the exam, we systematically check all four quadrants of the visual field, moving from top to bottom. Never go in the same order when doing an examination otherwise the patient will guess the pattern. If you start the sensory examination The upper quadrants correspond to the left hemisphere and the lower part of the occipital lobe, while the lower quadrants project to the right hemisphere in the cortical cortex. Specifically, the right upper quadrant projects to the left hemisphere in the lower part of the occipital lobe, located below the calcarine sulcus. Conversely, the right lower quadrant is processed above the calcarine sulcus in the occipital lobe. This pattern applies similarly to the left quadrants, which are processed in the right hemisphere. When assessing patients who have suffered a stroke or are in a coma and unresponsive, we can perform specific neurological tests to evaluate their condition. One common test is to observe the protective blink reflex. This involves approaching the patient from one side and trying to touch their eye to see if the reflex is activated, in other words moving your hand close to the patient’s eye without actually touching it to induce a blink reflex by simulating an object coming towards the eye. We should get really close and even touch the eyelashes to make them feel like next time we are going to touch their eye. Sometimes it’s enough to just move your hands really close to their eye to induce the reflex, but if the patient is not afraid then they might not blink, so to make them more afraid we can touch their eyelashes. It is important to note that this test differs from the corneal blink test, which assesses the function of cranial nerves V (trigeminal) and VII (facial).  Pag. 16 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves c. Patterns of visual field loss There are specific patterns of visual field loss associated with lesions in different locations. Visual field loss 1. Amaurosis, which is complete loss of vision in one eye but normal vision in the other eye. The main causes of amaurosis are: o vascular-related issues, such as thrombosis or ischemia. A specific condition associated with this is known as Amaurosis Fugax. This occurs when there is a plaque in the carotid artery that dislodges, leading to a small embolus entering the ophthalmic artery. This results in ischemia of the optic nerve, causing a sudden loss of vision. Amaurosis Fugax is akin to a transient ischemic attack (TIA), and patients typically do not experience permanent blindness because these small emboli usually dissolve on their own. However, there are instances where they may persist longer, resulting in acute visual disturbances. Patients experiencing Amaurosis Fugax may become confused as their vision suddenly declines. A TIA carries a significant risk, with 17-20% of patients experiencing a stroke on the same day. In some cases, the embolus may not remain in the ophthalmic artery and may instead travel to the brain, leading to a stroke. o Another potential cause of amaurosis is acute inflammation, as seen in conditions like Multiple Sclerosis (MS). In about 20% of patients, MS manifests as loss of vision in one eye, referred to as optic neuritis. This condition is distinct in MS because its onset is gradual, taking hours to develop, and tends to last longer.  Pag. 17 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves Since the optic nerve consists of central nervous system (CNS) myelin, and MS specifically affects CNS myelin, many patients presenting with vision loss seek help from eye specialists who may then refer them to neurologists upon finding no ocular issues. MS typically affects younger individuals, with a peak age range of 20-40 years, making it a primary consideration when a young patient presents with sudden vision loss. o While infections can also lead to amaurosis, they are relatively rare. o Intoxication is another possible cause of vision loss in one eye. Historically, incidents occurred in Italy when individuals made wine using methanol instead of ethanol, resulting in widespread blindness due to methanol's toxicity. o Additionally, deficiencies in vitamins B12 or B1 can also lead to vision loss in one eye. When evaluating patients with vision loss in one eye, it's crucial to differentiate between inflammation of the optic nerve (optic neuritis) and anterior ischemic optic neuropathy (AION). Key distinctions between these conditions include: o Age: Optic neuritis typically occurs in younger patients, while AION is more common in older individuals. o Progression: Optic neuritis usually presents with a rapid progression over a matter of days, whereas AION presents acutely. o Pain: Pain is a common symptom in optic neuritis, whereas it is infrequent in AION. o Optic Disc Appearance: The optic disc appears normal in cases of optic neuritis, while edema is typically present in AION. In modern clinical practice, we rarely perform fundoscopic examinations, as we now rely primarily on CT scans for diagnosis. However, the fundoscope is a small instrument used to inspect the bottom of the eye, specifically the optic disc (or papilla). By examining the papilla, we can identify signs of vasculitis and inflammation of the blood vessels. At the optic disc, we can also observe the central features of the optic nerve, including the arteries and veins that supply it. The significance of examining the fundus lies in its connection to intracranial pressure (ICP). The optic nerve is enveloped by meninges and is directly linked to the subarachnoid space, establishing a critical relationship. In cases of brain tumors or trauma, the growth of additional tissue within the skull can compress the brain and elevated intracranial pressure. This increase in pressure can lead to symptoms such as headache, resulting from the irritation of the meninges. Furthermore, elevated pressure can impede blood flow to the optic nerve, leading to papilledema. Papilledema is characterized by swelling of the optic disc due to increased ICP. In earlier medical practices, prior to widespread access to CT scans, assessing the fundus was crucial for diagnosing acute conditions, such as meningitis. In such scenarios, performing a lumbar puncture was common to check for elevated ICP. If a patient had elevated pressure due to a tumor, a lumbar puncture could inadvertently lead to herniation through the foramen magnum. Thus, observing the fundus for papilledema became essential, especially in patients who were comatose, as they might not report headaches. Nowadays, when a patient arrives at the emergency room, we typically send them for a CT scan, which provides a comprehensive understanding of their condition. In addition to papilledema, other forms of inflammation can affect the optic disc. For instance, papillitis occurs in cases of optic neuritis, representing both edema and inflammation. Other conditions can lead to optic atrophy, which may stem from degenerative diseases or inflammatory processes causing nerve damage and subsequent atrophy.  Pag. 18 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves  Pag. 19 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves 2. Bitemporal hemianopia, loss of the outer visual fields in both eyes, indicates a lesion at the level of the optic chiasm. The medial fibers, which carry visual information from the temporal visual field, cross at the chiasm. Therefore, a lesion in this area affects the crossing fibers from both eyes, resulting in a loss of peripheral vision. Conversely, the fibers from the lateral retina, which carry information from the central visual field, do not cross over. Thus, patients retain their ability to see objects in the central visual field. Bitemporal hemianopsia is relatively rare in general clinical practice but frequently associated with specific conditions such as: o Pituitary Adenoma: This benign tumor of the pituitary gland can grow and exert pressure on the optic chiasm, leading to visual field deficits. o Craniopharyngioma: Another type of tumor that can affect the pituitary gland and surrounding structures, also resulting in similar visual field loss. o Empty Sella Syndrome: This condition occurs when the sella turcica, the bony structure that houses the pituitary gland, is filled with cerebrospinal fluid (CSF) rather than the pituitary gland itself. It can also lead to pressure on the optic chiasm and resultant visual disturbances. 3. Lateral homonymous Hemianopia is defined as the loss of the same half of the visual field in both eyes. It can result from lesions in various locations along the visual pathway posteriorly to the optic chiasm (such as at position 3, 4 or 5 in the above diagram), so in the brain. It could be in the optic tract or in the parietal lobe or in the occipital lobe. This could be caused by a: o brain infarct, o brain hemorrhage, o brain trauma, o brain tumor o demyelinating disease such as MS.  Pag. 20 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves When a patient presents with neurological symptoms, it's essential to consider how these symptoms correlate with the location of the lesion. Once you locate the site of the lesion then you start to think what could be the possible cause that can affect this site For instance, if a patient exhibits weakness in an arm and leg, one might suspect a lesion affecting motor pathways at the medulla, cervical spinal cord, or higher up in the brain. If sensory deficits accompany motor weakness, the lesion might be located even higher in the brain. In cases of diplopia (double vision) alongside paralysis, there may be an implication of a cranial nerve (like CN III) involvement, possibly indicating a midbrain lesion due to the proximity of cranial nerves to the motor pathways. 3. Loss of visual alignment a. Control of eye movements (CN III, CN IV and CN VI) Now we move on to the control of eye movement, an important topic. There are two areas responsible for eye movement: one is voluntary and located in the frontal area, while the other is in the occipital area and is involved in reflex movements. For example, when you're on a train and observe objects passing by outside, you may not move your head; instead, you only move your eyes. This is known as pursuit movement. The control of eye movement begins at the level of the III and IV cranial nerve nuclei. These nuclei are responsible for controlling the eye muscles, specifically the superior rectus and superior oblique. It is important to understand that images must be processed by both eyes in areas specifically designated to receive information from their respective visual fields. Referring to the first image below, when we focus on the nearest point, that object is centered on the fovea. However, objects behind it (represented as points farther away) do not focus on the fovea; instead, they land on a spot medial to the fovea on the retina.  Pag. 21 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves Hold your finger in front of you and another finger far behind it. When you focus on the finger in front, the one in the periphery may appear blurry or even double. Conversely, when you shift your focus to the finger that is farther away, the one closer to you may look double. The key issue here is that when we don’t focus on an object, the light rays do not fall on the fovea; instead, they land on non-corresponding areas of the retina, resulting in double vision. If the images don’t align on corresponding areas that are meant to perceive the same object, you see double. However, we typically disregard this because our primary concern is what we are actively focusing on. When there is a lesion that affects eye movement, images fail to reach the corresponding areas of the retina, causing the brain to perceive double vision. One known condition is congenital strabismus, where individuals may have misaligned eyes but do not experience double vision because they adapt to relying on one eye. For instance, if I sustain an injury to one eye, I might find that I can see better with that eye than with both. Over time, I learn when to use one eye and when to use both. People with divergent strabismus may appear to see double, but in reality, they do not, as they have learned to rely solely on one eye. In the image below, the three relevant nuclei are circled: the III nucleus located in the midbrain, the VI cranial nerve (abducens) nucleus in the pons, and the IV cranial nerve (trochlear) nucleus, which is also situated in the midbrain.  Pag. 22 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves b. Eye inspection and examination When we begin an examination, we start with taking the patient’s history. It's important to observe the patient closely, particularly their eyes and the palpebral rim, to check for signs such as ptosis, protruding eyes, or enophthalmos. We also assess the pupils to ensure they are round and of equal size. Additionally, we examine ocular alignment and look for any conjunctival injection. These factors are crucial, as a patient may only report double vision, but the examination may reveal other significant signs. To examine eye movements, we use a pen and instruct the patient to follow it with their eyes. This test, known as the H test, evaluates the activity of different eye muscles. The image below outlines the muscles being tested in each eye, along with the corresponding nerves. If there is malalignment, the patient will experience double vision, and our task is to determine the location of the lesion: is it in the III, IV, or VI cranial nerve? Performing the H shape is essential because it allows us to assess each muscle individually. At each position, we can ask the patient if they see double. If they are at a specific position, we can identify which muscle is affected. This knowledge helps us pinpoint the affected nerve and its nucleus. Remember that diplopia indicates damage along the pathway, which could be at the level of the nerve, in the midbrain, or in the pons where the affected nucleus resides. When a patient reports double vision, we must mentally reconstruct the functional anatomy that controls eye movement. Eye movements are regulated by cranial nerve nuclei; the nerve exits the nucleus and innervates the muscle at the neuromuscular junction (NMJ). In conditions like Myasthenia gravis, these NMJs are compromised. Therefore, the lesion could be at any of these sites: the nerve, nucleus, NMJ, or muscle. One of the leading causes of diplopia in adults is Myasthenia gravis.  Pag. 23 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves Next, we need to test additional aspects of eye function. We examine both the upper and lower eyelids and assess convergence, which requires the synchronized action of the two medial recti. To test convergence, we ask the patient to focus on a pen or finger as it moves closer to their nose. During this test, we observe miosis (pupil constriction) and convergence, effectively assessing the accommodation reflex. The following reflex to test is the pupillary light reflex, which involves both the II cranial nerve and the oculomotor nerve (III cranial nerve). It’s important to instruct the patient to move only their eyes to follow the target, avoiding head movement. c. Cranial nerve palsy Understanding the function of each nerve is crucial. The III cranial nerve controls all eye muscles except for the lateral rectus (controlled by the VI cranial nerve) and the superior oblique (controlled by the IV cranial nerve). Most cases of diplopia result from a lesion of the III cranial nerve, which also affects upper eyelid movements, leading to ptosis. This ptosis serves as a defense mechanism: since double vision requires both eyes, covering one eye allows the patient to see without double vision. However, long-term ptosis can result in misalignment of the eyes. In typical III cranial nerve palsy, the patient presents with ptosis. When we lift the eyelid, we may observe divergent strabismus, where the two eyes are not aligned. A key characteristic is that when the patient attempts to move the eye in the opposite direction of the strabismus, the diplopia worsens due to greater misalignment. Conversely, looking in the same direction as the strabismus decreases diplopia, as the misalignment lessens, bringing the image closer to the correct position. In the image below, panel D shows the eyes looking in the same direction and appearing almost normal, while panel C shows them looking in two different directions. One important rule regarding diplopia is that it tends to worsen when looking in the opposite direction of the strabismus. Remember, when evaluating a patient with III cranial nerve palsy, ptosis is a critical sign.  Pag. 24 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves In cases of VI cranial nerve lesions, the patient may experience issues on one side. In the first position (A) in the image below, they might see double. When they move their eyes in one direction (B), they may be fine, but if they have right-sided palsy and attempt to look in the opposite direction, the affected eye doesn’t move, resulting in diplopia (C). VI CN palsy is significant because it is one of the first nerves affected by increased intracranial pressure. For example, in patients with a tumor or trauma, these signs may be observed. This occurs because the VI CN is the longest cranial nerve and is frequently compromised in such conditions. In VI CN palsy, the patient appears normal when trying to adduct the affected eye, as adduction is controlled by the medial rectus muscle, which is innervated by the III CN. However, when they attempt to abduct the affected eye, diplopia worsens, since abduction is controlled by the lateral rectus muscle, innervated by the VI CN. Even when looking straight ahead, the diplopia may persist. A sign associated with ocular misalignment is strabismus, which can be either convergent or divergent. - Convergent strabismus can occur with VI cranial nerve (CN) palsy. When this nerve is affected, the muscles are under tonic contraction, and all the extrinsic ocular muscles work to maintain normal eye alignment. In the case of VI CN palsy, the lateral rectus muscle, which pulls the eye outward, is weakened. As a result, the medial rectus muscle becomes predominant, causing the eye to turn inward and resulting in convergent strabismus.  Pag. 25 a 25 International Medical School – NS – NEURO #1 – prof. Nobile – Intro, semiology & examination of cranial nerves - Conversely, in III CN palsy, which affects multiple eye muscles except for the lateral rectus and superior oblique, the eye tends to diverge. This happens because there are no opposing muscles to balance the pull of the lateral rectus, leading to divergent strabismus in the primary position. Thus, in III CN palsy, we observe divergent strabismus, while in VI CN palsy, we see convergent strabismus. When a patient experiences diplopia, it is crucial to understand the functional anatomy of the eyes and the pathways of the cranial nerves. Diplopia may indicate a lesion in the midbrain, but patients might also present with additional signs related to lesions in the midbrain or pons. For example, pyramidal signs may be present, such as in Cross syndrome, where there is III CN palsy along with contralateral limb paralysis. This occurs due to an infarct affecting the area of the midbrain containing the III CN nucleus and the crossing pyramidal tracts, resulting in ischemia impacting both structures. Trochlear nerve (IV CN) palsy can be more challenging to diagnose. The trochlear nerve controls the superior oblique muscle, which adducts the eyes and brings them down. Patients with IV CN palsy often report diplopia, particularly when descending stairs, as this activity heavily engages the affected muscle. In the primary position, IV CN palsy may be difficult to detect, which is why the H shape test is essential; it allows us to assess each muscle and nerve involved in eye movement. The main causes of oculomotor nerve palsy (CN III, CN IV and CN VI): Ischemia, diabetes, hypertension: o vasculitis (PAN, temporal arteritis) i.e. vascular lesion of the nerve. These lesions may be intrinsic, like a small stroke affecting the nerve, or may result from inflammation. It’s important to consider that a patient with recurrent headaches might also present with cranial nerve palsy. In some cases, an aneurysm—an abnormal dilation of a blood vessel—can compress the nerve. Therefore, when a patient presents with recurrent headaches along with III cranial nerve palsy, it’s crucial to exclude the possibility of an aneurysm. Appropriate imaging and examinations should be conducted to assess for this condition. o thrombosis/aneurysm/fistula/inflammation of cavernous sinus o orbital inflammation (pseudotumor orbits) o compression (brain hernia, tumour, cranial hyper/hypotension) o aneurysm of Willis Circle or SAE o Infiltration (carcinomatous meningitis, lymphoma) o inflammatory neuritis (GBS, CIDP) Brainstem lesions. o brainstem stroke (hemorrhage, infarct) o brainstem tumor o brainstem encephalitis o multiple sclerosis Muscle and neuromuscular junction diseases o hyperthyroidism o ocular dystrophy o myasthenia gravis (most cause of diplopia in adults)