Intracranial hypotension syndrome is an uncommon manifestation of shunt overdrainage; characterized by a triad of postural headache, diffuse pachymeningeal gadolinium enhancement and low cerebrospinal fluid opening pressure. We describe a young female with recurrent episodes of postural headaches and reversible dorsal midbrain syndrome due to intracranial hypotension as a complication of shunt overdrainage, and a subsequent improvement following shunt ligation.

Phenytoin is one of the commonly used antiepileptic drugs. The common dose dependent and reversible neurological side effects of phenytoin are nystagmus, diplopia, dysarthria, ataxia, incoordination, chorioathetosis, orofacial dyskinesias and drowsiness. Persistent cerebellar dysfunction with cerebellar atrophy is a well known complication of long term phenytoin use. There are several mechanisms proposed including hypoxia due to frequent seizures or toxic effects of phenytoin on cerebellar Purkinje cells. However, irreversible cerebellar dysfunction following acute phenytoin intoxication is rare. We report a 20 year old female who presented with nystagmus, dysarthria, limb and truncal ataxia with orofacial dyskinesias and chorea. She also had cognitive and affective symptoms in the form of reduced attention, slow responses, lalling speech, blunting of affect, inappropriate laughter, reduced self care and executive dysfunction. The symptoms started 2 weeks following the initiation of phenytoin 300mg/ day, given prophylactically following left basal ganglia bleed. Her serum phenytoin was in toxic range, hence phenytoin was stopped. Her PET scan revealed bilateral cerebellar hypometabolism. At 6 months follow up, she had persistent ataxia with cognitive and affective dysfunction and follow up MRI showed diffuse cerebellar atrophy. The clinical and radiological fi ndings suggest that acute phenytoin intoxication is responsible for persistent ataxia and cerebellar cognitive affective syndrome.

Progressive multifocal leukoencephalopathy (PML) is a progressive lethal demyelinating disease of the brain, caused by JC virus. Reactivation of JC virus due to reduction of cellular immunity especially in setting of AIDS, is the commonest underlying cause. PML has classically been described in individuals with profound cellular immunosuppression such as patients with AIDS, haematological malignancies, organ transplant recipients or those treated with immunosuppressive or immunomodulatory medications for autoimmune diseases. Rarely it has also been diagnosed in cases with no or minimal immunosuppression. Here, we report a 50 year-old man who presented with sudden onset multiple neurologic defi cits. Neuroimaging, histopathology, and virology studies confi rmed the diagnosis of PML. We could not however demonstrate any underlying immunodefi ciency state. Our case suggests that absence of immunodefi ciency does not exclude the possibility of PML and should be considered in immunocompetent patients with a typical clinical course and neuroimaging fi ndings.