Clinical exam skills: a complicated headache
Ian Bickle, Michael Watt, and Steven McKinstry kick off our new series on typical medical school clinical examination questions
A 26 year old woman was admitted to hospital with headache, double vision, and visual disturbance. She had been on holiday to Spain six weeks previously, and before flying home she had had four days of vomiting from a presumed viral illness. For the next four weeks she had had severe headaches, which were worse on coughing and stooping. These headaches were most apparent first thing in the morning and were only partially relieved by simple analgesics. The double vision was noted in all directions of gaze but was worst when she looked to the left (figs 1 to 5). There is the occasional "spot" (floater) in her vision.
Fig 1
Fig 2
Fig 3
Fig 4
Fig 5
Her past medical history was of recurrent left ear infections as a child. She is on no regular medications and has an intrauterine contraceptive device in situ. On examination her blood pressure was 128/73 mm Hg, blood glucose was 4.9 mmol/l, and body mass index (weight (kg)/(height (m))2) was 34 kg/m2. Fundoscopy was done (figs 6 and 7).
Fig 6
Fig 7
Questions
- Describe the findings on examination of gaze.
- What are the potential causes of these findings?
- Describe the findings on fundoscopy.
- What are the potential causes of these findings?
- What is your differential diagnosis for this woman's condition?
Answers
(1) There is a left sixth nerve (abducens) palsy. On looking straight ahead there is a convergent squint--the left eye deviated medially. On left lateral gaze there is failure of the left eye to abduct past the midline (the lateral rectus muscle is innervated by the abducens nerve). There was associated double vision.
(2) Causes of a sixth nerve palsy include multiple sclerosis, hypertension, diabetes, basal meningitis, encephalitis, any cause of mononeuritis multiplex (vasculitis, sarcoidosis), and raised intracranial pressure.
(3) There is bilateral haemorrhagic papilloedema. The disc margins are not clearly seen in either fundus. There are soft exudates surrounding the discs and haemorrhages--seen best in the inferonasal aspect of the right fundus. The veins are congested and the optic disc appears raised.
(4) Causes of papilloedema include malignant hypertension; idiopathic intracranial hypertension; and intracranial hypertension secondary to a space occupying lesion, such as a haematoma, abscess, or tumour. Less common causes include central retinal vein occlusion, venous sinus thrombosis, and metabolic conditions, such as hypercapnia.
(5) The two most likely diagnoses in a woman of this age with no previous medical illness and the above findings are idiopathic intracranial hypertension (still often referred to as benign intracranial hypertension) and venous sinus thrombosis.
Computed tomography or magnetic resonance imaging and lumbar puncture help in their differentiation. In this case, dynamic spiral computed tomography scanning with intravenous contrast showed the "empty delta" sign (fig 8) Thrombus appeared as a triangular filling defect within the superior sagittal sinus, contrasting with the normal dura around its margins. This appearance is characteristic of sagittal sinus thrombosis.
Fig 8 Computed tomograph showing empty delta sign (arrow)
She was started on therapeutic low molecular weight heparin and given warfarin before discharge. Visual fields were closely monitored--the initial tests showing bilaterally enlarged blind spots. The papilloedema is secondary to the raised intracranial pressure caused by obstruction to the normal venous drainage of the cerebral hemispheres and resultant back-pressure venous oedema.
The sixth nerve palsy is a false localising sign again due to the raised intracranial pressure stretching the sixth nerve during its long intracranial route. The risk factors for sinus thrombosis include pregnancy, the puerperium, blood dyscrasias, malignancy, paraneoplastic syndromes, use of the oral contraceptive pill, and dehydration.
Ian C Bickle medical senior house officer,
Email: clonvara@yahoo.co.uk
Michael Watt consultant neurologist,
Steven McKinstry consultant neuroradiologist, Royal Victoria Hospital, Belfast
studentBMJ 2004;12:309-348 SeptemberISSN 0966-6494
