Isolated palatal tremor as unique clinical manifestation of SCA 18 due to a new mutation of IFRD1
Echeveste B (1), Covarrubias E (2), Cabello JP (3), Luquin MR (4)
A 62-year old man was seen at the Department of Neurology of the University of Navarra Clinic because of speech difficulties, marked by a tremulous voice. He did not report other symptoms such as ear-clicking, ocular myoclonus or gait instability.
He had been treated with different drugs for bipolar disorder, and his speaking impairment was considered a drug-induced side effect. There was no family history of tremor, ataxia or other neurological diseases. At physical examination, a palatal tremor and a trembling voice were noted (Video 1).
The rest of the neurological examination, including gait, was normal. Brain MRI (3 T) was performed and a high intensity signal of the inferior olive and cerebellar atrophy in the T2 FLAIR sequence was observed (Fig. 1). Genetic study for ataxias (199-gene panel) including the more common gene mutations associated with cerebellar disorders was performed.
We found a novel and possibly pathogenic mutation in the IFRD1 gene [c.4C>G(p.Pro2Ala)]. Interestingly, mutations in this gene have been associated with SCA 18.
The patient was treated with botulinum toxin injections in the tensor veli palatine muscle with a marked improvement of palatal tremor and tremulous voice without serious side effects.
CITATION Parkinsonism Relat Disord. 2017 Sep;42:100-101. doi: 10.1016/j.parkreldis.2017.05.026.