Pure akinesia: an unusual phenotype of Hallervorden-Spatz syndrome.

Two siblings were seen in our outpatient movement disorders clinic with an indolent clinical picture of a pure akinesia syndrome. Magnetic resonance showed the typical "eye of the tiger" sign, and genetic screening disclosed that both siblings were compound heterozygotes with two missense mutations in the PANK2 gene 734A-->G and 1172T-->C. This case report highlights the phenotypic diversity of Hallervorden Spatz syndrome and the need for further investigation of adult-onset pure akinesia syndromes.