The standard recommended treatment for lateral sinus thrombosis is intravenous antibiotics. For those that fail, some authors recommend anticoagulant therapy, others internal jugular vein ligation. Despite these recommendations, there is still a significant mortality in all reported large series and the main reason this is that the cause of the failure has not been found or investigated.

Over a six-year-period, from January 1985 to December 1990,36 patients were admitted with lateral sinus thrombosis. The initial treatment consisted of intravenous antibiotics and surgery. The surgery included cortical mastoidectomy for non-cholesteatomatous ears and modified radical mastoidectomy for cholesteatomatous ears and drainage of the intracranial collection of pus in patients with subdural empyema and brain abscess.

There were nine failures (25 per cent) with this treatment regimen. Blood cultures and pus swab of the ears were taken from these patients. The blood cultures were positive in four patients and the organisms isolated included (3-haemolytic Streptococcus sp. in two, Proteus mirabilis and Streptococcuspneumoniae in one each). From the ear swab mixed cultures were found in eight and a single organism in one.

Gram-negative organisms were isolated in nine (100 per cent), Proteus mirabilis in eight (89 per cent) and Enterobacter sp. in two. Both these organisms were resistant to ampicillin and penicillin but were sensitive to amikacin.

Amikacin was then added to the treatment regimen and a dramatic response with a fall in the temperature, and improvement in the patients' general condition was noted within 24 hours, in all patients. There was not a single death, despite the fact that 42 per cent of the patients had other associated intracranial complications. The conclusion is that the treatment of choice for patients refractory to the conventional antibiotic therapy and surgery is amikacin therapy and not internal jugular vein ligation, or anticoagulant therapy.