Neurology Exam Quiz

CNS Pathology

• CNS pathology covers infections, routes, pyogenic meningitis, causes of meningitis, complications, meningitis pathology, aseptic (viral) meningitis, Brudzinski's and Kernig's signs, TB meningitis, diagnosis and management, brain abscess, encephalitis, acute encephalitis pathology, slow encephalitis, prion disease, toxoplasmosis, TORCH complex, increased intracranial pressure, space-occupying lesions, brain herniation, brain edema, mannitol and hypertonic saline, hydrocephalus, cerebrovascular accidents, cerebral infarction, transient ischemic attacks (TIAs), cerebral hemorrhage, head injury, extradural hematoma, subdural hematoma, intracerebral hemorrhage, degenerative diseases, and diseases of myelin.

Pathology of CNS Infections

• CNS infections involve meningitis, encephalitis, brain abscess, and different types of infections (bacterial, viral, fungal, parasitic).
• Routes of infection include blood (trauma), direct extension (e.g., from otitis media), and nerves (e.g., rabies and herpes).

Pyogenic Meningitis

• An acute infection of the meninges.
• Anatomical types include leptomeningitis (pia + arachnoid matter), and pachymeningitis (dura).

Causes of Meningitis (examples)

• Neonates: Group B streptococci, E coli, Listeria monocytogenes.
• Children/Teenagers: Streptococcus pneumoniae, H influenza (non-vaccinated infants)
• Adults/Elderly: Streptococcus pneumoniae.
• Children: Coxsackie virus (fecal-oral transmission)

Meningitis Pathology

• Sub arachnoid pus
• CSF organization
• Turbid CSF
• Hydrocephalus
• Normal cortex

Aseptic (Viral) Meningitis

• Usually mild, with complete recovery.
• Common pathogens include HSV, CMV, enteroviruses, and mumps.
• CSF characteristics: clear, lymphocytosis, normal sugar, slightly increased protein.

Brudzinski's and Kernig's Signs (Examples)

• Brudzinski's sign: flexion of the hips and knees in response to neck flexion.
• Kernig's sign: resistance to extension of the leg while the hip is flexed.
• Used to diagnose meningitis.

Brain Abscess

• Localized collection of capsulated pus.
• Causes: bacterial, fungal, parasitic, tumor.
• Source: direct, metastatic.
• Clinical effects: similar to a space-occupying lesion, leading to increased intracranial pressure (ICP), focal neurological deficits, and potentially epilepsy and coma.

Encephalitis

• Inflammation of the brain tissue (usually viral).
• Forms: acute (HSV, HZV, rabies), persistent (PMLE, SSPE), slow (prions).
• Clinical features: severe mental status changes, focal neurological deficits, potentially seizures and/or coma. Potentially fatal.
• Pathology (examples): perivascular inflammation, glial hyperplasia, inclusion bodies, neuronal damage (e.g., temporal lobe necrosis in HSV, disseminated necrosis in CMV).

Acute Encephalitis Pathology

• Perivascular inflammation
• Glial hyperplasia
• Inclusion bodies
• Neuronal damage
• HSV: Temporal lobe necrosis
• CMV: Disseminated necrosis
• Rabies: Negri bodies

Slow Encephalitis (Prion Diseases)

• Caused by abnormal infectious proteins (prions) leading to the degeneration of brain cells.
• Forms: Creutzfeldt–Jakob disease (CJD), Kuru.
• Types: indigenous and exogenous (e.g., mad-cow disease).

Additional CNS Pathologies / Neurological disorders

• Toxoplasmosis: Parasitic brain infection, common in neonates (transplacental from infected mother). Infection of food contaminated with animal urine/feces, especially cat feces.
• TORCH Complex: Infectious disorders, including toxoplasmosis, rubella, CMV, and herpes simplex virus. Symptoms include microcephaly, central nervous system (CNS) calcifications, petechial rash, hepatosplenomegaly, and thrombocytopenia.
• Increased Intracranial Pressure (ICP): High pressure inside the skull due to space-occupying lesions (e.g., abscess or hematoma, tumors, recent infarcts, brain edema). Effects: headache, vomiting, papilledema, coma, and brain herniation, which causes further neuronal damage.
• Brain Herniation: Pushing of the brain tissue due to increased intracranial pressure.
• Brain Edema: Swelling of the brain tissue due to intracellular & extracellular water accumulation (vasogenic, cytotoxic). Effects: vascular damage, CSF flow obstruction, neuronal damage. Treatment using mannitol and hypertonic saline.
• Hydrocephalus: Increased Cerebrospinal Fluid (CSF) volume in the cranium due to production, obstruction, or reabsorption issues. Infants: large head circumference and mental retardation. Adults: dilated ventricles and brain atrophy.
• Cerebrovascular Accidents (CVA): Includes cerebral infarction (ischemia) and cerebral hemorrhage. Infarction: due to arterial narrowing (thrombosis, atheroma), shock, and increased intracranial pressure. Pathology (examples). Clinical effects. TIA: transient ischemic attacks. Cerebral hemorrhage: caused by hypertension (HT), tumors, bleeding disorders, arteriovenous malformations. Pathology: initial bleeding -> increased intracranial pressure -> death -> later cyst formation, subarachnoid hemorrhage. Xanthochromia - yellow discoloration of CSF (bilirubin).
• Head Injury: Trauma causes concussion, skull fracture, contusions (Delayed onset edema and CSF leakage, hematomas - Extradural, intradural). Effects: scarring and shrinking, potentially leading to epilepsy.
• Extradural Hematoma: Rupture of middle meningeal artery due to linear skull fracture. Rapid recovery phase, later elevated intracranial pressure (↑ICP), surgical draining (burr holes).
• Subdural Hematoma: Rupture of small bridging veins caused by trauma. Can worsen and lead to brain herniation/coma. Potentially chronic.
• Intracerebral Hemorrhage: Bleeding within the brain tissue. Common cause of sever brain injury in severely traumatic cases, potentially fatal.
• Degenerative Diseases: loss of functional neurons. Examples: Alzheimer's disease, Parkinsonism.

Degenerative Diseases

• Alzheimer's Disease: Progressive dementia with impaired memory, challenges with daily tasks, and confusion. Causes include genetics, lifestyle, environmental factors, but sometimes trauma and toxins.. Pathology: gross brain atrophy, senile plaques (amyloid), neurofibrillary tangles, cerebral amyloid.
• Parkinsonism: Loss of pigmented neurons in the basal ganglia, ↓dopamine secretion. Causes include idiopathic PD, trauma, post-infectious states, and toxins. Clinical features: Tremor (rest), rigidity (cogwheel), bradykinesia (mask facies), festinating gait, postural instability. Pathology: degeneration of basal ganglia, reduced dopamine secretion, Lewy inclusion bodies.
• Other Degenerative Diseases: Other related neurological disorders. Some can be from a variety of factors.

Diseases of Myelin

• Multiple Sclerosis: Autoimmune disorder causing demyelination of white matter in the CNS. Clinical findings: progressive with relapse/remission; variable neurological symptoms (sensory and motor); loss of myelin sheath, plaque formation, and inflammatory cell response.
• Other related disorders: Some types of leukodystrophy, demyelinating neuropathy examples.

Diseases Of Peripheral Nerves

• Demyelinating neuropathies (e.g., Guillain-Barré syndrome, chronic inflammatory demyelinating polyneuropathy). Axonal neuropathies(e.g., hypertrophic neuropathies, examples of viral infections, alcoholic/drug-induced neuropathies, diabetic neuropathies).

Brain Tumors

• Classification: Secondary (metastatic) or Primary. Important factors: Age and location. Benign tumors are sometimes also harmful. Malignant tumors tend to metastasize, while benign tumors are typically localized.
• WHO Classification: based on neuroepithelial tissue (embryonic, glial, mixed tumors), tumors of meninges, cranial and spinal nerves, lymphomas/hematopoietic neoplasms, germ cell tumors, cysts, tumor-like lesions, sellar region, local extensions from regional tumors, and metastasis.
• Gliomas (examples: astrocytoma, oligodendroglioma, ependymoma, mixed gliomas). Astrocytomas (types: fibrillary, pilocytic, anaplastic, glioblastoma multiforme).
• Ependymomas: Usually benign; around the ventricles.
• Oligodendrogliomas: Rare; in cerebral white matter. Better prognosis than other gliomas.
• Meningiomas: from arachnoid granulations, usually benign, slow growth, often present as space-occupying lesions (SOL).
• Medulloblastomas: Primitive neuroectodermal tumors in the cerebellum, can result in hydrocephalus.
• Peripheral Nerve Sheath Tumors (examples: schwannomas, neurofibromas).

Neural Tube Defects

• Failure of closure of the neural tube, resulting in defects of the vertebrae, skull, meninges, spinal cord, or brain, often linked to maternal folic acid deficiency. Spina bifida (types: occulta, with different degrees of spinal abnormalities).