Mrs Robertson was 34 years old and someone you could not help but like. She was cheerful, always turned up to reviews when asked and never troubled us with minor ailments.
In fact, since the birth of her two children we rarely saw her apart from follow-up visits for her oral contraception. So when she presented complaining of a headache, I was quite surprised. But it was soon obvious that this was no ordinary headache.
She volunteered that although she had the occasional headache, this one was by far the worst she had experienced. She had woken in the night with it, so by the time she came to afternoon surgery it had been there for about 10 hours and was getting worse.
She had been feeling sick since the headache began, and had vomited twice. She also said it was affecting her eyes.
My first thought was that this was a migraine with visual disturbance, perhaps aggravated by her oral contraception.
As I talked to her and performed a brief neurological examination, I became more concerned. The headache was not unilateral, the visual disturbance was persisting long after onset, and it did not involve flashing lights or similar migraine-related phenomena, but was just 'a sort of blurring'.
I found it difficult to find her lower limb reflexes, and we both felt that her right leg seemed weaker than the left.
Despite once being told by an eminent neurologist that looking at the fundi of patients presenting with headache was a waste of time, I have always done this. It only takes a minute, and I think it reassures patients that you are taking their problem seriously.
I have also never forgotten the time when I was a medical registrar and looked into the eyes of a 21-year-old soldier with long-standing intermittent headaches and saw the papilloedema that alerted me to his brain tumour.
When I examined Mrs Robertson's fundi, I saw quite distinct evidence of bilateral papilloedema. Clearly this was no ordinary headache. I spoke to the neurology SHO, who arranged her immediate admission.
I called the hospital the next day and was told she had undergone an immediate CT scan that showed a superior sagittal sinus thrombosis. She was being sedated and given heparin.
It sounded pretty grim, so I was surprised and delighted when three weeks later she walked into my surgery looking more like her normal self. She was taking warfarin, and had stopped taking her combined pill, which she had been told was the probable cause of her cerebral venous thrombosis (CVT).
In about 14 per cent of cases, there is no obvious risk factor for CVT. Apart from combined oral contraception, other associated conditions include head injury, pregnancy, dehydration, infections of the sinuses or ears, hypercoagulable states, collagen diseases, haemolytic diseases, and procedures such as lumbar puncture, jugular catheterisation or craniotomy.1
The papilloedema was caused by increased intracranial pressure from the partial or complete occlusion of a cerebral venous sinus.
Mrs Robertson was unusual in one respect, in that she had a sudden severe onset of her headache. It is much more common for the headache to be mild or moderate, and gradual in onset.
In the most severe cases, there is a decreasing level of consciousness. This may be due to repeated seizures or from generalised swelling of the brain with herniation.
Cavernous sinus thrombosis is almost always associated with infection of the paranasal sinuses. In these cases there is often evidence of ocular movement abnormalities, periorbital oedema and proptosis.
Other recognised patterns of symptomatology can occur if the transverse or sigmoid sinuses are affected, or the jugular bulb is involved.
Headache in some form occurs in nearly 90 per cent of patients, but papilloedema, general or focal seizures, and evidence of paresis are only found in about one third of cases.2
The differential diagnosis of CVT includes subarachnoid haemorrhage, ischaemic stroke, intracranial haemorrhage, brain tumour and intracranial abscess.
I was surprised to find that anticoagulation is the mainstay of treatment, even in patients with evidence of cerebral ischaemia or haemorrhage. The warfarin is continued for four to six months, unless there is a predisposition to coagulation.
Thrombolytic therapy is reserved for those who deteriorate despite anticoagulation.
If the diagnosis is made early, as was happily the case with Mrs Robertson, the prognosis is remarkably good, with full recovery in some 70 per cent of cases. Of the other 30 per cent, two thirds are left with some degree of neurological deficit, and one third die.
Surprisingly, the development of seizures or a comatose state does not significantly affect the short-term outcome and all cases should be treated vigorously. The long-term recurrence rate is 20 per cent.
It was worrying that a healthy young woman had developed this potentially life-threatening complication and I wondered whether I should reconsider my screening procedures for this form of contraception.
Data on how many cases of CVT are caused by combined oral contraceptives are thin on the ground, but I did discover that the overall incidence of the condition is of the order of three to four cases per million of the population.
So I feel more relaxed about it now and have probably seen my one case for several professional lifetimes.
- Dr Barnard is a former GP in Fareham, Hampshire
1. Fink J N, McAuley D L. Cerebral venous sinus thrombosis: a diagnostic challenge. Int Med J 2001; 31: 384-90.
2. Schwedt T J, Matharu M S, Dodick D W. Thunderclap headache. Lancet Neurol 2006; 5: 621-31.