FXTAS presenting with cervical dystonia as the initial symptom: Considering FXTAS in the clinical evaluation of cervical dystonia.

FXTAS (Fragile X-associated tremor/ataxia syndrome) is characterized by typical clinical features, including tremor, cerebellar ataxia, parkinsonism, and the middle cerebellar peduncle (MCP) sign, which appears as T2 hyperintensity in the MCP on MRI. FXTAS is almost never considered in the context of cervical dystonia. However, this case demonstrates that FXTAS can initially present with cervical dystonia. A 59-year-old man presented with cervical dystonia, characterized by right lateral flexion, and sensory trick. His initial symptom was cervical tilt at age 54. At age 55, the patient developed an unsteady gait. The patient was unable to perform a tandem gait and stand up from a crouch, suggesting trunk ataxia, and exhibited lateral gaze nystagmus, which was indicative of a cerebellar disorder. MRI revealed MCP sign. Genetic testing confirmed FXTAS, revealing 90 CGG repeats in the (Fragile X Mental Retardation 1) gene. Notably, a pre-symptomatic MRI, incidentally acquired at the age of 52, retrospectively revealed the presence of the MCP sign. This suggests that, even when FXTAS initially presents as cervical dystonia, the MCP sign can remain a reliable diagnostic feature for early detection. This case highlights that early FXTAS may mimic idiopathic cervical dystonia and that considering FXTAS during the clinical evaluation of cervical dystonia can enable early diagnosis.