Thu7October0140PM 9

A 65-year-old male presents with acute severe headache, ataxia, and vomiting. Six hours later he became drowsy.

On examination he had left horizontal nystagmus, a partial left sixth cranial nerve palsy, and extensor plantar responses. His blood pressure was 188/110 mmHg.

Which is the most likely cause for this deterioration?

(Please select 1 option)

Cerebral oedema

Malignant hypertension

Non-convulsive status epilepticus

Dehydration

Brain stem herniation Correct

Explanation

The most likely explanation of the sudden deterioration will be brain stem herniation. The sudden onset of headache, ataxia, and vomiting a few hours prior to this suggest that there may have been an intracranial haemorrhage which led to mass effect and subsequent herniation.

Brain herniation often causes false localising signs due to compression of various areas of the brain. There are various forms of herniation, which are outside the scope of this question. Simply, it usually follows two patterns: uncal herniation or central herniation.

Clinical presentation of uncal herniation includes a third nerve paresis (ipsilateral dilated pupil, abnormal external ocular movements, including nystagmus), contralateral hemiparesis, which can lead to ipsilateral hemiparesis. The third nerve paresis occurs due to compression of the parasympathetic fibres around the third nerve, which results in unopposed sympathetic response. Contralateral hemiparesis occurs with compression of the cerebral peduncle. Ipsilateral hemiparesis and third nerve palsy occur late when the lateral translation is so great that it compresses the contralateral third nerve and peduncle.

Central herniation usually presents with confusion and drowsiness, followed by impaired vertical gaze, small pupils, impaired oculocephalic reflexes, and bilateral corticospinal tract signs including increased tone and Babinski signs.

Additional signs are present due to raised intracranial pressure: bradycardia, hypertension, irregular breathing (Cushing response), and a sixth-nerve palsy. The sixth nerve is usually the first to be compressed due to its long extracerebral intracranial course.

Diplopia from either a third or sixth nerve palsy can cause nystagmus.

This patient needs immediate intensive care support, with intubation and hyperventilation. The case should be discussed urgently with neurosurgeons, and their advice sought regarding the possibility of operative intervention. Intravenous mannitol and other hyperosmolar solutions are oftenindicated, and should be considered.

Cerebral oedema could account for the sixth nerve palsy, nystagmus, and hypertension, but the deterioration with impaired consciousness and extensor plantar responses should lead you to consider herniation as the cause.

Dehydration would not cause this constellation of neurological signs.

The blood pressure in malignant hypertension is typically higher than this (>220/120 mmHg).

This history is not typical for status epilepticus.