Neurology PDF

Neurology This Photo by Unknown author is licensed under CC BY-NC-ND. Dr. Haider Abdul Alridha  Cells of the nervous system ❑ The neurone is the functioning unit of the nervous system. Each neurone has a cell body and axon terminating at a synapse, suppo...

Neurology This Photo by Unknown author is licensed under CC BY-NC-ND. Dr. Haider Abdul Alridha  Cells of the nervous system ❑ The neurone is the functioning unit of the nervous system. Each neurone has a cell body and axon terminating at a synapse, supported by astrocytes and microglial cells. ❑ Astrocytes provide the structural framework for the neurones, control their biochemical environment and form the blood–brain barrier. ❑ Microglial cells are blood-derived mononuclear macrophages with immune and scavenging functions. ❑ Ependymal cells line the cerebral ventricles. ❑ In the CNS, oligodendrocytes produce and maintain a myelin sheath around the axons. In the PNS myelin is produced by Schwann cells Cerebral hemispheres The cerebral hemispheres coordinate the highest level of nervous function, the anterior half dealing with executive (‘doing’) functions and the posterior half constructing a perception of the environment. Each cerebral hemisphere has four functionally specialised lobes, with some functions being distributed asymmetrically (‘lateralised’), to produce cerebral dominance for functions such as motor control, speech or memory. Cerebral dominance aligns limb dominance with language function: in right- handed individuals the left hemisphere is almost always dominant, while around half of left-handers have a dominant right hemisphere. Anatomy of the cerebral cortex Cortical lobar functions Frontal Parietal: Parietal: non- Temporal: Temporal: Occipital dominant dominant dominant non- dominant ⮚ Personality ⮚ Language ⮚ Spatial ⮚ Auditory ⮚ Auditory ⮚ Visual ⮚ Emotional ⮚ Calculation orientation perception perception ⮚ processin control ⮚ Constructional ⮚ Melody/pitc g ⮚ Social skills ⮚ Language h perception behaviour ⮚ Verbal ⮚ Non-verbal ⮚ Contralateral memory memory motor ⮚ Smell ⮚ Smell control ⮚ Balance ⮚ Language ⮚ Micturition Brainstem Formed of; Midbrain Pons Medulla Connected to; Cerebral hemisphere by cerebral peduncles Cerebellum by cerebellar peduncles The brainstem ⮚ In addition to containing all the sensory and motor pathways entering and leaving the hemispheres, the brainstem houses the nuclei and projections of most cranial nerves, as well as other important collections of neurons in the reticular formation. The cerebellum The cerebellum is an organ of balance, located in the posterior fossa of the skull, separated from the occipital lobe by a dural fold, the tentorium cerebelli. It overlies the dorsal portion of the pons and medulla and contributes to the formation of the roof of the fourth ventricle. The cerebellum is responsible for smoothing out and refining voluntary movement. The cerebellum is divided into three major lobes by transverse fissures: the flocculonodular lobe, the anterior lobe and the posterior lobe. The ⮚ Circuits between the basal extrapyramidal ganglia and the motor system cortex constitute the extrapyramidal system, which controls muscle tone, body posture and the initiation of movement.  The spinal cord ❑ It lies in the spinal canal & ends at the lower border of the first lumbar vertebra. ❑ The lower most 3 segments of the spinal cord (S3, S4, S5) are known anatomically as the conus medullaris while the above 4 segments (L4, L5, S1, S2) are known anatomically as the epiconus. ❑ It is formed of gray matter (cells) surrounded by white matter. ❑ In a transverse section the gray matter resembles the letter H (2 anterior, 2 posterior horns). ❑ The white matter contains ascending and descending fibers arranged into tracts. The spinal cord ⮚ The spinal cord is the route for virtually all communication between the extracranial structures and the CNS. ⮚ Afferent and efferent fibres are grouped in discrete bundles but collections of cells in the grey matter are responsible for lower- order motor reflexes and the primary processing of sensory information. Peripheral nervous system ⮚ The peripheral nervous system includes the nerves and ganglia outside the brain and spinal cord. ⮚ The peripheral nervous system (PNS) is made up of two divisions: the somatic nervous system and the autonomic system. ⮚ Nerves can also be classified as ‘cranial’ or ‘spinal’ according to where they exit the CNS. ⮚ Cranial nerves emerge from the cranium (brain and brainstem) whilst spinal nerves leave the CNS via the spinal cord. There are 12 pairs of cranial nerves and 31 spinal nerve pairs, The cranial nerves Cranial Name Fibres Functions nerve I Olfactory Sensory ⮚ Smell II Optic Sensory ⮚ Vision III Oculomotor Motor ⮚ Extra-ocular muscles except superior oblique and lateral rectus; pupillary constriction IV Trochlear Motor ⮚ Superior oblique V Trigeminal Motor and ⮚ Sensation over the face; muscles of sensory mastication VI Abducens Motor ⮚ Lateral rectus muscle The cranial nerves Cranial nerve Name Fibres Functions VII Facial Motor and ⮚ Muscles of facial expression sensory ⮚ Stapedius muscle ⮚ Taste sensation from anterior two-thirds of tongue VIII vestibulocochlear Sensory ⮚ Balance and hearing IX Glossopharyngeal Motor sensory and ⮚ Sensation pharynx, ear, posterior third of tongue. secretory ⮚ Secretory fibres to parotid. ⮚ Motor fibres to stylopharyngeus X Vagus Motor and sensory ⮚ Sensation pharynx and larynx Muscles of pharynx, larynx and palate XI Accessory Motor ⮚ Trapezius and sternocleidomastoid muscles XII Hypoglossal Motor ⮚ Muscles of the tongue  APPROACH TO THE PATIENT WITH NEUROLOGIC DISEASE ❑For neurological assessment, there must be step by step clinical methodology that does not fail. ❑The first step involves gathering information, also known as establishing the database. Patients evaluated by history and examination. ❑Electrodiagnostic testing, neuroimaging, and laboratory investigation should be used as an extension of and not as a substitute for taking a good history and do a proper general and neurologic examination. The neurological diagnosis is achieved by ⮚carefully evaluating the patient (gathering information) ⮚analyzing the information (Evaluation of information by breaking it into its component parts to uncover their interrelationships and understand cause-effect relationships) ⮚write the possible scenarios ⮚developing a list of differential diagnoses ⮚confirm the provisional diagnosis and exclude other possibilities The neurological diagnosis ❑The practical endpoint of analyzing the information, gathered from neurological assessment, includes answering the two questions what is and where is the lesion? ❑The neurologist, unlike most other physicians, approaches the patient from an anatomic view by determination of where in the nervous system, the damage has occurred, leaving issues of etiology to be addressed later. The neurological diagnosis ❑(What) and (where) may be answered by history alone, if not, (where) should be answered by examination but we may need investigation to answer (what).  1) Define the symptoms, the nature, and the extent of deficits. The method to 2) Determine the temporal answer the profile question (what) 3) Evaluate the modifying we should: (aggravating and relieving) factors: 4) Absent symptoms. Important negative. The temporal profile a) Mode of onset: Peak of the severity in the timeline of the illness. (Sudden, Acute, Subacute, and Chronic). sudden onset: the symptoms reach completion immediately b) Course and pattern: Variation over time. (Persistent, episodic, relapsing- remitting, diurnal variation, improving and steady worsen). c) Chronologic evolution: The accumulation of different symptoms over time. (Which symptoms came first and order in which follow i.e. chronologic sequence of events). The evolution of symptoms Sudden: vascular, seizure, trauma Acute: infectious, and Immunological Subacute: infectious, Immunological, and neoplastic Chronic: degenerative, genetic, and developmental disorders  Note ❑Metabolic abnormalities, drugs, and toxins can cause neurologic dysfunction over nearly any time course (depending on the type of metabolic abnormality, drug, or toxin)  (Where is the lesion?) ⮚Localization of the lesion to a specific part of the nervous system is the essential step in evaluating patients with neurological manifestations. ⮚Localization is the identification of which site of the nervous system has been affected. Lesions should be localized to one or more of the following regions: 2. 3. Peripheral 4. Root and 1. Muscle Neuromuscular nerve Plexus junction 5. Spinal cord 6. Brainstem 7. Basal ganglia 8. Cerebellum 9. Cerebrum (cortical and 10. meninges subcortical)  Any area in the nervous system represents itself by its function. The site of the lesion expresses itself through neurologic dysfunction. Symptoms. and signs are the shadows of the neurological dysfunction Neurological emergencies Status epilepticus Stroke (if thrombolysis or mechanical thrombectomy available) Guillain–Barré syndrome Myasthenia gravis (if bulbar and/or respiratory) Spinal cord compression Subarachnoid haemorrhage Neuroleptic malignant syndrome How to take a neurological history Introduction ⮚ Age and sex ⮚ Handedness Presenting complaint Background ⮚ Symptoms clarify ⮚ Previous neurological symptoms and whether ⮚ Overall pattern: intermittent or persistent? similar to current symptoms ⮚ If intermittent, how often do symptoms occur and ⮚ Previous medical history how long do they last? ⮚ Domestic situation ⮚ Speed of onset: seconds, minutes, hours, days, ⮚ Driving licence status weeks, months, years, decades? ⮚ Medications (current and at time of symptom ⮚ Better, worse or the same over time? onset) Alcohol/smoking habits ⮚ Associated symptoms (including non-neurological) ⮚ Recreational drug and other toxin exposure ⮚ Disability caused by symptoms Change in ⮚ Family history and developmental history walking ⮚ Difficulty with fine hand movements, e.g. writing, ⮚ What are patient's thoughts/fears/concerns? fastening buttons, using cutlery ⮚ Effect on work, family life and leisure