Movement disorders of familial neuroacanthocytosis syndrome.

Characteristic movement disorders were observed in two siblings who had neuroacanthocytosis syndrome with normal serum lipoprotein levels. The disorders included orolingual tic-like movements associated with vocalization, biting of the lip and tongue, peculiar dysphagia with bird-like drinking, and postural lapse with abrupt buckling of the knees. In addition, subtle features of parkinsonism and chorea were observed. These movement problems are strikingly similar to those described in cases of neuroacanthocytosis syndrome in several other familial and sporadic cases. Careful observations of these unusual movement disorders may provide a clue to the diagnosis of this rare syndrome.