module 1 neurological disorders

What is hydrocephalus?

The accumulation of excess CSF within the ventricles, causing ventricular enlargement and sometimes raised intracranial pressure.

What are the two main causes of hydrocephalus?

1. Blockage within the ventricles (causes dilation before the blockage)

2. Reduced absorption at arachnoid granulations (causes dilation of all ventricles)

How does hydrocephalus present in newborns vs. adults?

• Newborns: Enlarged head due to unfused skull bones.

• Adults/older children: Gradual ventricular dilation, compression, and thinning of brain tissue.

What is meningitis?

Inflammation of the pia-arachnoid mater (meninges).

What typically causes meningitis?

Bacterial or viral infection (most common CNS infection).

What are common symptoms of meningitis?

Fever, headache, vomiting, and stiff neck.

How is meningitis diagnosed and treated?

Diagnosed by lumbar puncture (examining CSF); treated with antibiotics.

Why can facial infections spread to the cavernous sinus?

Emissary and ophthalmic veins lack valves, allowing retrograde flow of infection from the facial area (nose and upper lip) to the cavernous sinus, risking thrombosis or meningitis.

What is a subdural haemorrhage?

Bleeding between the dura mater and arachnoid mater, enlarging the subdural space; often due to head trauma.

What is a subarachnoid haemorrhage?

Bleeding into the subarachnoid space from damaged vessels, resulting in blood in the CSF; often due to head trauma.

What are the effects of frontal cortex damage?

Personality changes, as seen in Phineas Gage (often negative or disinhibited behaviour).

What happens when the somatosensory association cortex is damaged?

The person cannot recognize objects by touch alone (tactile agnosia).

What is bitemporal hemianopia (tunnel vision) and what causes it?

Loss of peripheral vision in both eyes due to damage at the optic chiasm (e.g., from a pituitary tumor).

What is the result of optic nerve damage?

Monocular blindness in the ipsilateral (same side) eye.

What happens with optic tract damage?

Homonymous hemianopsia — loss of the same visual field (contralateral) in both eyes (e.g., right tract → left visual field loss).

What can happen when intracranial pressure rises rapidly?

Cerebellar tonsils may herniate through the foramen magnum, compressing the medulla — can be fatal due to respiratory and cardiovascular centre compression.

What is the effect of damage to the substantia nigra?

Loss of dopaminergic neurons → Parkinson’s disease; difficulty initiating movement.

Why is damage to the medulla fatal?

It controls vital functions — cardiovascular, respiratory, and reflex centres.

What is split brain?

A condition where the corpus callosum (connecting the hemispheres) is absent or severed, preventing communication between hemispheres.

What is an example of split-brain behaviour?

A person may name an object seen by one eye but not by the other, due to lack of interhemispheric transfer.

What is Bell’s palsy?

Paralysis of the facial nerve (CN VII), causing inability to control facial muscles on the affected side; may result from facial canal infection.

What is trigeminal neuralgia (Tic Douloureux)?

Severe facial pain due to CN V inflammation or compression; can be triggered by mild stimuli (“suicide disease”).

How is trigeminal neuralgia treated?

Analgesics are partly effective; nerve cutting relieves pain but causes loss of sensation.

What are the effects of CN XII (hypoglossal nerve) damage?

• Both sides: Inability to protrude the tongue.

• One side: Tongue deviates toward the injured side and atrophies.