A previously well 24 year old man presented to the emergency department with a two week history of worsening temporal headache and non-specific coryzal symptoms. Due to the protracted course of his symptoms he was initially triaged to minors. On medical assessment, it emerged he had consulted his general practitioner earlier in the course of the illness. He had been prescribed and had completed a course of oral amoxicillin. Twenty four hours before attendance, he developed persistent vomiting and an occipital headache. He complained of neck pain and also of photophobia.

On examination, he had a temperature of 38 °C, and was supporting his head in extension with his hands, while vomiting continuously. He could not tolerate funduscopy because of the photophobia, and his headache worsened on lying down. There were no other significant findings.

Due to his presentation, his case was discussed with the on-call radiologist, who was initially reluctant to perform an emergency CT head scan due to the long history and normal Glasgow Coma Scale score. However, while in the department, the patient developed a mild degree of confusion, (GCS 14, E₄V₄M₆) and the scan was performed. It showed a large, right sided, subdural collection in the frontal region. It was 1 cm deep, with associated mass effect, but no midline shift, and contained a 3 mm fleck of gas. There was dural enhancement (fig 1). The right maxillary sinus was also opacified with pus (fig 2).

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Figure 1

 CT scan showing dural enhancement.

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Figure 2

 CT scan showing opaque right maxillary sinus.

The patient was immediately referred to the neurosurgical team at an adjacent hospital. However, prior to transfer, he deteriorated further (GCS 12, E₃V₃M₆). He also developed a right sided ptosis with a dilated, sluggish right pupil. After further discussion with the neurosurgical team, the patient was given intravenous ceftriaxone, metronidazole, dexamethasone, and mannitol.

After transfer the patient underwent a right frontal microcraniotomy and bilateral antral washouts; 60 ml of foul yellow pus was drained. The patient was ventilated overnight. The pus culture revealed Streptococcus milleri and mixed anaerobic species. The organisms were sensitive to penicillin and metronidazole. The patient was discharged back to the referring unit a week later, on oral co-amoxiclav and phenytoin.

DISCUSSION

Subdural empyema is a collection of pus in the space between the outermost layers of the meninges, the dura, and the arachnoid. Young male patients in their second or third decade of life are most commonly affected.¹ It is mainly a complication of sinusitis, less frequently otitis media or neurosurgical procedures. With prompt diagnosis and aggressive treatment, overall mortality is still as high as 20%.¹ Recurrence is common requiring further surgery. It has high morbidity of neurological sequelae, particularly epilepsy, and fits may occur years later.

Subdural empyema has a rapid, fulminating course and presents with headache, fever, vomiting, impaired consciousness, and focal neurology. As in our case, a history of preceding sinusitis is not always obvious. CT scan is nearly always diagnostic² but can be equivocal and further imaging with repeat CT or magnetic resonance imaging may be warranted. Subdural empyema is a neurosurgical emergency, the treatment of choice being prompt surgical drainage, simultaneous eradication of the primary source of sepsis, and systemic antibiotics.