Tableau d'encéphalite de Bickerstaff et hypertension intracrânienne

A 20-year-old man had progressive headache, neck pain and visual loss after upper airway infection. After 3 weeks, he developed ophtalmoplegia, ataxia, areflexia, autonomic failure, four limbs paresis with impaired consciousness. Brain and cervical MRI were normal. Ophthalmological examination confirmed bilateral papilledema. Cerebro-spinal fluid pressure was high, cell count was normal and proteins were mildly elevated. Electromyography showed presence of both proximal and distal demyelination. Electroencephalogram was slowed, with diffuse delta and theta waves. Anti-GM1 and GQ1b antibodies were negative. The patient was treated with intravenous immunoglobulins (0.4 g/kg/day) for 5 days, associated with high doses of acetazolamide and corticosteroids for papilledema. His neurological condition improved for gait, strength, pain, ophtalmoplegia and ataxia. He kept severe visual loss with optic atrophy. Diagnosis is discussed: Bickerstaff encephalitis with intracranial hypertension or malignant pseudotumor cerebri?