Spectrum of Movement Disorders in Niemann-Pick Disease Type C.

INTRODUCTION: Niemann-Pick disease type C (NPC) is an autosomal recessive neurovisceral lipid storage disorder caused by mutations in the NPC 1 or 2 genes. Movement disorders can occur as the first symptom and as predominant symptom mainly in juvenile-onset. The frequency and heterogeneity of movement disorders in NPC are not well described. We studied the frequency and spectrum of movement disorders in patients with NPC of different age of onset.

METHODS: Retrospective chart review of patients with NPC diagnosed based on the Suspicion Index tool and demonstration of foamy macrophages/sea-blue histiocytes in bone marrow aspirate.

RESULTS: We report 9 cases of NPC with 2 patients of late-infantile, 4 juvenile-onset and 3 of adult-onset. The mean age at onset of symptoms was 11.7 ± 10.4 (range 4-38 years) and the median duration of illness was 4 years. Vertical supranuclear gaze palsy (VSGP) was noted in 8 patients and VSGP with slowing of saccade in 1 patient. Splenomegaly was seen in 5 patients. Movement disorders as the first symptom occurred in 4 patients. Dystonia was the first symptom in 2 patients and cerebellar ataxia in 2 patients. Cerebellar ataxia occurred during the course of illness in 5 patients, dystonia in 6 patients. One patient with late-infantile NPC had stimulus-sensitive myoclonus.

CONCLUSION: Movement disorders are common in NPC and occur as a presenting symptom. Cerebellar ataxia and dystonia are the most common movement disorder in NPC. Vertical supranuclear gaze palsy along with the movement disorders should lead to clinical suspicion of NPC.