Visual hallucinations and the cholinergic system in dementia.

insonism has been reported; that patient also had pyramidal signs.4A further patient exhibited dopa-responsive tremor and facial impassivity during recovery from a more typical presentation of pontine myelinolysis with stupor, abnormal eye movements and tetraparesis.'Pathological changes in the basal ganglia have been well documented in typical cases of pontine myelinolysis,6 and it has been suggested that the pontine lesion masks the extra-pontine clinical features.In our case the large lesion in the pons was clinically silent.MRI is clearly the investigation of choice in patients presenting with neurological syndromes associated with hyponatraemia; subclinical or clinically atypical pontine myelinolysis may be more common than is currently realised.