Objective: To treat the medication-resistant tremor of SCA12 by Deep brain stimulation (DBS)

Background: Action tremor might be the most prominent feature of SCA12 patient and could affect the quality of life severely. The tremor in some patients were medication-resistant. DBS is an effective treatment of medication-resistant tremor, but was rarely reported in the tremor treatment in SCA12.

Method: The tremor was rated by Fahn-Tolosa-Marin Tremor Rating Scale (FTMTRS) and Tremor Research Group Essential Tremor Rating Assessment Scale (TETRAS). The cerebellar ataxia was rated by International Cooperative Ataxia Rating Scale (ICARS). The Quality of life was rated by TETRAS activities of daily living (ADL).

Results: The 58-year-old female patient with autosomal dominant family history suffered from action tremor in head and both arms, slurred speech and walking instability for 5 years (Fig 1A, B). She took primidone 50 mg twice a day and topiramate 25 mg twice a day but with poor response. She exhibited a right dominant postural and intention tremor in both upper extremities. Spasmodic torticollis, head tremor, gaze-evoked nystagmus, mild dysarthria and mild tandem gait impairment were observed. Genetic testing indicated a CAG triplet expansion in SCA12 (8/44) (Fig 1C). A bilateral PSA-VIM DBS was performed to treat the tremor (Fig. 1D, E). Four weeks after operation, when the stimulation was on, the tremor obviously decreased by a monopolar stimulation in the lowest contact (left hemisphere 160Hz, 70μs, 2.0V, right hemisphere 170Hz, 70μs, 1.9V). The scores for scales of tremor and cerebellar ataxia improved, with FTMTRS from 68/144 to 23/144, TETRAS performance subscale from 39/64 to 13/64, ICARS from 39/100 to 31/100.

At one year follow-up, the tremor was under control by monopolar stimulation in the lowest contact after adjusting the parameters (left hemisphere, 180Hz, 90μs, 3.4V, right hemisphere, 170Hz, 60μs, 3.0V). Though the cerebellar ataxia developed with ICARS score rebounding to that of pre-operation, the quality of life was better than that of pre-operation rating by the decreasing scores of TETRAS ADL from 41/48 to 35/48 (Fig 1F).

Conclusion: DBS is a therapy for the suppression of tremor of a variety of etiologies including SCA12. cZI may be a better target for SCA12 than VIM.

Fig1. Clinical features of the patient with SCA12

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MDS Abstracts - https://www.mdsabstracts.org/abstract/deep-brain-stimulation-of-bilateral-ventral-intermediate-nucleus-in-a-patient-with-spinocerebellar-ataxia-type-12/