Pantothenate kinase associated neurodegeneration in late adulthood: an atypical case from India

Abstract

Pantothenate kinase associated neurodegeneration (PKAN) is a rare autosomal recessive disorder and the most common subtype of neurodegeneration with brain iron accumulation (NBIA). While classical PKAN typically presents in childhood, atypical forms may manifest later in life with heterogeneous neurological and psychiatric features, often resulting in diagnostic delay. We report a case of atypical PKAN in a 45-year-old woman who presented with a three-year history of progressive dysarthria, involuntary tongue protrusion, sialorrhea, difficulty in jaw closure, and involuntary movements of the right upper limb. Neurological examination revealed spastic dysarthria, oromandibular dystonia, orolingual chorea, rigidity, resting tremor, hyperreflexia, and a positive Hoffmann sign. Psychiatric manifestations included anxiety, depressive episodes, and impulsivity. Routine laboratory investigations were unremarkable except for mild iron deficiency anaemia. Magnetic resonance imaging of the brain demonstrated the characteristic bilateral “eye of the tiger” sign in the globus pallidus, strongly supporting the diagnosis of PKAN. The patient was treated with trihexyphenidyl, tetrabenazine, botulinum toxin injections, and supportive therapy. This case highlights the importance of considering PKAN in the differential diagnosis of adult onset movement disorders with psychiatric manifestations. Recognition of its characteristic neuroimaging features is essential for timely diagnosis, appropriate symptomatic management, and genetic counselling. The rarity of adult onset PKAN and its diverse clinical presentation underscore the need for greater awareness among clinicians.