NEuROSuRGERY

100 Cases in Surgery

ANSWER 86

The Glasgow Coma Score (GCS) is composed of three parameters: verbal commands, eye opening and motor responses. The patient is assessed on their ‘best’ response. The scores are summed to give an overall value from 3 (being the worst) to 15 (being the best). In this case, the GCS is 13. While the score is useful in absolute terms, such as defining coma (GCS <8), the main value of the GCS is being able to monitor the ongoing neurological status of a patient by repeated assessment every 15min. A fall in the score of 2 or more should prompt an urgent review of the patient, as this indicates a potentially significant deterioration in their condition.

The most likely diagnosis in this case is of a subarachnoid haemorrhage. The classical symptoms are of a severe ‘thunderclap’ headache affecting the back of the head that reaches maximal intensity within a few seconds.

!Causes of bleeding into the subarachnoid space

•85 per cent: saccular aneurysms in the cerebral vasculature – ‘berry’ aneurysms

•15 per cent: non-aneursymal subarachnoid haemorrhage:

•arterial dissection

•arteriovenous malformation

•tumour

•Cocaine abuse

•trauma

•Septic aneurysm

The initial management involves stabilizing the patient and arranging the following:

•Blood tests: full blood count, renal function, coagulation screen and group and save

•Computerized tomography (CT) of the brain: to look for evidence of subarachnoid blood and hydrocephalus

•Lumbar puncture: if the CT scan does not show any pathology, then cerebral spinal fluid should be sent for spectrophotometric analysis to look for the presence of oxyhaemoglobin and bilirubin.

Differential diagnoses include transient ischaemic attacks, migraine or epilepsy.

Patients confirmed to have a subarachnoid haemorrhage should be stabilized and then referred as soon as possible to a neurosurgical unit. This will allow further assessment of the cause of the bleed normally using cerebral angiography to see if an aneurysm can be identified.

Further management of ruptured cerebral aneurysms is directed at preventing re-bleeding. Treatment has changed recently with the advent of endovascular techniques to ‘coil’ aneurysms, thereby making them safe. Previously, patients would have to undergo a craniotomy in order for the aneurysm to be directly visualized and a ‘clip’ placed over the neck of the aneurysm to seal it off from the main circulation.

The International Subarachnoid Aneurysm Trial (ISAT) demonstrated that in the group where patients with aneurysms were randomized to undergo endovascular coiling, there was a significant reduction in mortality and morbidity when compared to the group randomized to surgical ‘clipping’.

KEY POINTS

•the gCS ranges from 3 to 15.

•a fall of 2 points or more should prompt immediate reassessment.

200

Neurosurgery

CASE 87: ConFuSion aFter a Fall

history

You are asked to review a 78-year-old man on the observation ward. He was admitted the previous evening with confusion. Earlier in the evening a friend visited and reported that he had fallen over 3 weeks ago and had become increasingly confused and clumsy.

He takes a calcium antagonist for essential hypertension and aspirin since a previous heart attack. He lives alone and is independent and self-caring. He is a non-smoker, but there had been concerns over his increasing alcohol intake following the death of his wife 5 years ago.

examination

He has a normal temperature with a pulse rate of 78/min and a blood pressure of 136/86 mmHg. The cardiorespiratory and abdominal systems appear normal. He is confused in time, place and person. His pupils are symmetrical and reactive. The rest of his cranial nerve and peripheral neurological examinations are normal.

INVESTIGATIONS

See Figure 87.1.

Figure 87.1 imaging of the head. (reproduced with kind permission from liebenberg W. a. et al. 2006. Neurosurgery Explained. vesuvius books ltd.)

Questions

•What investigation is shown, and what is the diagnosis?

•Which factors in the history make you suspicious of this diagnosis?

201

100 Cases in Surgery

ANSWER 87

This man has a chronic subdural haematoma (CSDH) shown on a CT scan (arrow in Figure 87.1). This condition is twice as common in men as women. Risk factors include chronic alcoholism, epilepsy, anticoagulant therapy (including aspirin) and thrombocytopenia.

CSDH is more common in elderly patients due to cerebral atrophy. It is thought that cortical bridging veins are put under tension as the brain gradually shrinks away from the skull. This patient has had a minor head injury in the preceding weeks, causing one of these cortical veins to tear. The history of potential alcohol abuse and aspirin use also contribute to the bleeding risk. Slow bleeding from the low-pressure venous system often allows a large haematoma to form before clinical signs become evident.

Initial misdiagnosis is, unfortunately, quite common. Before the advent of CT scanning, CSDH was known as the ‘great imitator’ as it was often mistaken for dementia, transient ischaemic attacks or strokes.

The CT findings for subdural haematomas change with time. In the first week, the blood is hyperdense compared to brain tissue. In the second and third weeks, the haematoma appears isodense compared to brain tissue; and after the third week, the blood appears hypodense compared to brain tissue.

The term ‘chronic' is applied to subdural haematomas that are older than 21 days. When there is no clear history of a head injury (25–50 per cent of patients), the diagnosis can be made radiologically according to the CT appearances of the blood.

Once the diagnosis is made, the liquefied blood can be drained via one or two Burr holes. Even for patients with significant comorbidities, operative intervention is not contraindicated as this procedure can be performed under local anaesthetic. Eighty per cent of patients will return to their previous level of function.

KEY POINTS

•the clinical signs of a chronic subdural haematoma can be subtle.

•a chronic subdural haematoma should be suspected in confused patients with a history of a fall.

202