Phasic Knee Bending Dystonic and Parkinsonian Gait: A Characteristic Finding in X-Linked Dystonia Parkinsonism.

BACKGROUND

X-linked dystonia parkinsonism (XDP) is a rare disorder characterized by adult-onset, progressive dystonia that, over time, is combined with or replaced by features of parkinsonism. Gait impairment is common.

METHODS

Case series of 4 XDP patients with a unique gait disorder.

RESULTS

The patients displayed a characteristic gait disorder with combined dystonic and parkinsonian gait features, with phasic knee bending. Of these patients, all had parkinsonism and three-quarters had prominent dystonic features, but 1 had predominant parkinsonism and subtle dystonic features.

CONCLUSION

Although XDP is a classic form of dystonia parkinsonism, some cases can mimic idiopathic Parkinson's disease. We describe a gait disorder which appears unique to XDP, involving phasic dystonic knee bending superimposed on parkinsonian shuffling, and may help clinically differentiate one of our parkinsonian-predominant patients from more-common forms of parkinsonism. The gait is distinct from other complex dystonic disorders with gait involvement.