Introduction
Spinocerebellar ataxia type 14 (SCA-14) is a rare autosomal dominant neurodegenerative disorder characterized by slowly progressive cerebellar dysfunction. The condition arises from mutations in the PRKCG gene, which encodes protein kinase C gamma, an enzyme critical for cerebellar Purkinje cell survival. This article presents a detailed case illustrating the typical clinical trajectory, genetic underpinnings, and neuroimaging findings of SCA-14.
Case Presentation
A 42-year-old woman presented with a two-year history of progressive dizziness that she described as a sensation of unsteadiness, particularly when walking or turning quickly. She also reported slurred speech and occasional difficulty with fine motor tasks, such as writing and buttoning clothing. There was no history of head trauma, stroke, or exposure to ototoxic medications. Her family history was notable for a paternal uncle with similar symptoms who was diagnosed with a cerebellar disorder of unknown etiology.
Neurological Examination
Examination revealed gaze-evoked nystagmus, dysarthria, and appendicular ataxia more prominent in the lower extremities. Finger-to-nose and heel-to-shin testing demonstrated dysmetria. Gait was wide-based and unsteady, consistent with truncal ataxia. Deep tendon reflexes were normal, and there was no evidence of parkinsonism or peripheral neuropathy. Romberg test was negative.
Neuroimaging and Genetic Analysis
Brain magnetic resonance imaging (MRI) demonstrated marked cerebellar atrophy, particularly affecting the vermis and hemispheric regions. The brainstem and cerebral hemispheres appeared normal. These findings were highly suggestive of a degenerative cerebellar condition. Given the family history and imaging pattern, genetic testing was pursued. A panel for hereditary ataxias revealed a heterozygous missense mutation in the PRKCG gene (c.274G>T; p.Arg92Trp), confirming the diagnosis of SCA-14. This specific mutation has been previously reported in families with early-onset ataxia and prominent dizziness.
Clinical Progression and Management
Over the subsequent three years, the patient’s dizziness became more incapacitating, requiring the use of a walking stick. Follow-up MRI showed progressive cerebellar atrophy. No curative therapy exists for SCA-14; management focused on symptom control. Physical therapy for balance training and adaptive strategies for dysarthria were beneficial. Vestibular suppressants were avoided due to risk of worsening ataxia. The patient was counseled on the autosomal dominant inheritance pattern and family planning options.
Discussion
SCA-14 is unique among the spinocerebellar ataxias because it often presents with relatively pure cerebellar dysfunction, without significant involvement of the brainstem or basal ganglia in early stages. Dizziness is a common initial symptom and may be misattributed to peripheral vestibular disorders, delaying diagnosis. The hallmark MRI finding of isolated cerebellar atrophy should prompt genetic testing for SCA-14. This case underscores the importance of a thorough family history and targeted genetic analysis in patients with progressive dizziness and ataxia.
Conclusion
This case highlights the classic presentation of SCA-14 with progressive dizziness, cerebellar atrophy on imaging, and a confirmed genetic mutation. Early recognition of the characteristic clinical and radiological features can facilitate appropriate counseling and management for patients and their families.