Objective: To present a case report of a patient exhibiting tremors as the primary manifestation of DYT-TOR1A at onset, along with a review of the literature regarding the prevalence of tremors in patients with DYT-TOR1A at onset.

Background: According to previous reviews reported in the literature, the highest prevalence of tremors in isolated dystonia is observed in DYT-HPCA and DYT-ANO3 gene variants; in combined dystonia, the highest prevalence is seen in DYT-SLC6A3¹. The classic presentation of DYT-TOR1A includes early onset within the first to third decades, isolated dystonia in a limb (lower limbs more commonly than upper limbs), and a positive family history². It usually exhibits caudal to cranial progression and becomes generalized over a period of months to years. Tremor is reported in 11%  of patients with DYT-TOR1A variants.¹

Method: We present the case of DYT-TOR1A, characterized by a tremor-dominant presentation, and review the literature to identify additional cases of DYT-TOR1A, particularly where tremor predominates at the disease onset.

Results: A 33-year-old male from non-consanguineous parents, with normal birth and development, reported experiencing head tremors and left upper limb tremors since he was 15 years old (for 18 years). He also displayed abnormal posturing in his left lower limb for 7 years, had difficulties writing for the last 2 years, and showed abnormal trunk posturing over the past 6 months. A trial of levodopa/carbidopa proved ineffective. Notably, the family history revealed three affected members [Figure-1].

Examination revealed postural tremors in the head, along with kinetic and postural tremors in the upper limbs, and more pronounced dystonic posturing in the left upper limb compared to the right. Tremors were also detected in the left foot, accompanied by dystonic posturing, truncal dystonia, and mild neck posturing. Brain MRI results were normal, while whole exome sequencing revealed a pathogenic variant c.907_909delGAG in DYT-TOR1A [Figure 2]

We identified and analyzed  61 articles involving 624 patients with genetically confirmed DYT-TOR1A. Among these patients, 31 (4.9%) exhibited predominant tremors at the onset of symptoms [Figure 3]. Predominant head tremors are rarely mentioned in the literature.

Conclusion: Tremor is observed in approximately 5% of cases of DYT-TOR1A at onset. Prominent tremors in the limbs and head may be the initial presentation of DYT-TOR1A, as demonstrated in our case.

Figure 1

Figure 2

Figure 3

References: 1. Pandey S, Bhattad S, Dinesh S. Tremor in Primary Monogenic Dystonia. Curr Neurol Neurosci Rep. 2021 Jul 15;21(9):48

2. Balint, B., Mencacci, N.E., Valente, E.M. et al. Dystonia. Nat Rev Dis Primers4, 25 (2018).

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