ANOTHERWISE HEALTHY middle-aged woman was experiencing gait instability.Neurological examination revealed truncal ataxia. Family history was negative. Brain and spinal cord 1.5-T magnetic resonance imaging (MRI) was performed and yielded normal results. Thyroid hormone, vitamin B12, and folic acid levels were normal. During the next 4 years, her walking difficulties progressed. She also developed palatal tremor. Repeated brain MRI revealed T2 hyperintensities in both olivary nuclei. Therefore, she was referred to our institution for further evaluation. On admission, the patient had severe palatal tremor (a video is available at http://www.archneurol .com) with Romberg and walking instability. She had no signs of pyramidal or sensory involvement and cognitive examination results were normal. Magnetic resonance imaging (3-T) was performed and revealed atrophy of the vermis and both cerebellar hemispheres and bilateral symmetrical hyperintensity of olivary nuclei (Figure). Brain singlephoton emission computed tomographic r esults w ere n ormal. Results of standard laboratory tests (sedimentation rate, complete blood count, serum glucose, electrolytes, liver enzymes, urea, creatinine, creatine kinase, lactate dehydrogenase, and C-reactive protein) were within normal limits. Serum and urine copper and ceruloplasmin levels were also normal. Results of genetic analysis for spinocerebellar ataxias 1, 2, 3, and 6; fragile X–associated tremor; ataxia syndrome; and Huntington disease were negative. Cerebrospinal fluid analysis revealed 1 lymphocyte and a slightly elevated protein level (0.062 g/dL [to convert to grams per liter, multiply by 10.0]) with negative oligoclonal bands. COMMENT Palatal tremors can be divided into essential palatal tremor, which is associated with normal brain MRI findings, and secondary palatal tremor, which is associated with structural lesions of the brainstem or cerebellum. 1 A distinct degenerative disease called progressive ataxia with palatal tremor has recently been described as an idiopathic or familial form of palatal tremor. 2 Characteristic MRI findings of the disease consist of bilateral hypertrophy of inferior olivary nuclei and mild cerebellar atrophy. Fludeoxyglucose F18 positron emission tomography shows hypometabolism in the red nucleus, external globus pallidus, and precuneus. Iodine I 123– radiolabeled 2-carbomethoxy-3(4-iodophenyl)-N-(3-fluoropropyl) nortropane single-photon emission computed tomography shows mild and progressive loss of striatal dopaminergic terminals, implicating dopaminergic dysfunction. 3 A very similar familial progressive ataxia with palatal tremor, spinocerebellar ataxia type 20, has been described with calcification of dentate nuclei. 4 Our patient did not have any structural lesions of the brainstem or cerebellum, and there was no calcification of the dentate nucleus. Her clinical presentation together with the 3-T MRI findings were consistent with a diagnosis of idiopathic progressive ataxia with palatal tremor.