This was a 12-week open-label study to assess the role of ultrasound-guided Onabotulinumtoxin-A (BoNT-A) injections for various types of hand and head tremor.

Focal treatment of head and limb tremor by onabotulinumtoxin-A (BoNT-A) injections has been inadequately investigated. Though few reports showed promising effects; yet, absence of wide scale studies, heterogeneous tremor presentation and diverse regimens to target a multi-joint tremulous movement make it difficult to reach an objective consensus regarding its value.

Participants (n=23) attended study visits at weeks 0, 4, 6 and 12. During each visit patients were subjected to standardized videotaping (during rest, posture and motion), Fahn-Tolosa-Marin (FTM) tremor motor scale, spiral drawings and UPDRS item 20 (rest tremor) for PD tremor. Injection paradigm was determined using surface EMG (tremor frequency) and ultrasonography of muscles that may contribute to the tremor across a variety of joints in all degrees of movement. All patients were injected with BoNT-A at baseline by US-guidance.

A significant decrease in FTM tremor severity score at week 6 (p< 0.01) with improvement in spiral drawing (P<0.05). In PD tremor, though some improvement was detected; yet, it was not statistically significant (P=0.06). Head tremor showed statistically significant improvement compared to those with limb tremor (P=0.04). Muscle weakness was detected in 3/15 patients with limb tremor.

BoNT-A could be a promising option for treatment of resistant to treat tremor. Precise directional assessment of tremor at each arm joint allowed for a better outcome in arm tremor.