Bilateral hipoglossal nerve palsy in necrotizing otitis externa.

Necrotizing otitis externa is a potentially lethal infection that starts in the external auditory canal and may progress to the skull base. It happens in elderly diabetic patients and is associated to a high morbi-mortality rate. The major causal agent is Pseudomonas aeruginosa, in 96 to 98% of the cases. The infection extends from the osteocartilaginous junction to the temporal bone by means of the Santorini fissures. The infection may progress towards the skull base and affect the facial, glossopharyngeal, vagus and accessory nerves. It may occasionally affect the hypoglossal, abducens and trigeminal nerves. Symptoms such as otalgia, headache, hypoacusis, otorrhea, in diabetic or immunosupressed patients are very relevant. Laboratory investigation reveals high ESR, with normal or mildly high white cell count. Clinical signs include ulceration on the floor of the EAC. CT scan shows bone destruction, and MRI shows both the location and extension of the infection, intracranial invasion and cranial nerve involvement. Scintigraphy with technetium and gallium has been used in order to assess cure criteria. Technetium scintigraphy is useful to diagnose osteitis, which is positive in cases of acute or chronic osteomyelitis, or trauma. It bears low specificity and may remain positive for one year. Galium-67 scintigraphy is used in the follow up and check of the therapeutic response, since galium has great affinity for acute phase leucocytes and proteins. Germ culture is necessary for proper treatment, however one should not wait for its result in order to start treatment. Two empirical antibiotics are used: aminoglycosides together with ciprofloxacin of cephtazidime. Alternative drugs are cefepime, cefoperazone, imipenem and aztreonam. Treatment lasts between 4 and 6 weeks. Otalgia reduction or cessation is an important control parameter. Most patients may be clinically treated, and surgery bears controversies, such as: progressive pain, cranial neuropathy and granulation persistence in the EAC. Mastoidectomy may be carried out, however in some cases it does not prevent skull base disease extension. CASE REPORT