Radiofrequency ablation for DYT-28 dystonia: short term follow-up of three adult cases

Neurosurgical and pharmacological management of dystonia

Dystonia characterizes a group of neurological movement disorders characterized by abnormal muscle movements, often with repetitive or sustained contraction resulting in abnormal posturing. Different types of dystonia present based on the affected body regions and play a prominent role in determining the potential efficacy of a given intervention. For most patients afflicted with these disorders, an exact cause is rarely identified, so treatment mainly focuses on symptomatic alleviation. Pharmacological agents, such as oral anticholinergic administration and botulinum toxin injection, play a major role in the initial treatment of patients. In more severe and/or refractory cases, focal areas for neurosurgical intervention are identified and targeted to improve quality of life. Deep brain stimulation (DBS) targets these anatomical locations to minimize dystonia symptoms. Surgical ablation procedures and peripheral denervation surgeries also offer potential treatment to patients who do not respond to DBS. These management options grant providers and patients the ability to weigh the benefits and risks for each individual patient profile. This review article explores these pharmacological and neurosurgical management modalities for dystonia, providing a comprehensive assessment of each of their benefits and shortcomings.

KMT2B-Related Dystonia in Indian Patients With Literature Review and Emphasis on Asian Cohort

OBJECTIVE

aaMutations in the KMT2B gene have been identified in patients previously diagnosed with idiopathic dystonia. Literature on KMT2B-related dystonia is sparse in the Indian and Asian populations.

METHODS

aaWe report seven patients with KMT2B-related dystonia studied prospectively from May 2021 to September 2022. Patients underwent deep clinical phenotyping and genetic testing by whole-exome sequencing (WES). A systematic literature search was performed to identify the spectrum of previously published KMT2B-related disorders in the Asian subcontinent.

RESULTS

aaThe seven identified patients with KMT2B-related dystonia had a median age at onset of four years. The majority experienced onset in the lower limbs (n = 5, 71.4%), with generalization at a median duration of 2 years. All patients except one had complex phenotypes manifesting as facial dysmorphism (n = 4), microcephaly (n = 3), developmental delay (n = 3), and short stature (n = 1). Magnetic resonance imaging (MRI) abnormalities were present in four cases. WES revealed novel mutations in the KMT2B gene in all patients except one. Compared to the largest cohort of patients with KMT2B-related disorders, the Asian cohort, comprising 42 patients, had a lower prevalence of female patients, facial dysmorphism, microcephaly, intellectual disability, and MRI abnormalities. Protein-truncating variants were more prevalent than missense variants. While microcephaly and short stature were more common in patients with missense mutations, facial dysmorphism was more common in patients with truncating variants. Deep brain stimulation, performed in 17 patients, had satisfactory outcomes.

CONCLUSION

aaThis is the largest series of patients with KMT2B-related disorders from India, further expanding the clinico-genotypic spectrum. The extended Asian cohort emphasizes the unique attributes of this part of the world.

Unilateral pallidothalamic tractotomy at Forel's field H1 for cervical dystonia

Background

Neurosurgical ablation of Forel's field H1 for cervical dystonia, which is currently abandoned, was formerly used in the 1960s–1970s. Regardless of the lack of neuroimaging modalities and objective evaluation scales, the reported efficacy was significant. Although recent studies have reappraised the ablation of the pallidothalamic tract at Forel's field H1 for Parkinson's disease, the efficacy for cervical dystonia has not been investigated well.

Methods

Data of 35 patients with cervical dystonia who underwent unilateral pallidothalamic tractotomy at Forel's field H1 were retrospectively analyzed. The Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) scores, the neck score of the Burke–Fahn–Marsden Dystonia Rating Scale (BFMDRS), and adverse events were evaluated preoperatively and at the last available follow‐up period.

Results

The mean clinical follow‐up period was 13.9 ± 6.5 months. The mean TWSTRS total scores were 34.3 ± 14.0 preoperatively and 18.4 ± 16.5 at the last available follow‐up period (46.4% improvement, p < 0.0001). The BFMDRS neck score also improved significantly from 6.2 ± 2.9 preoperatively to 2.8 ± 2.8 at the last available follow‐up period (55.0% improvement on the neck score, p < 0.0001). Reduced hand dexterity in seven patients, hypophonia in five patients, dysarthria in four patients, and executive dysfunction in one patient were confirmed as adverse events at the last available follow‐up evaluation. One patient had postoperative hemorrhage.

Conclusion

The current study confirmed significant improvement in TWSTRS total scores and BFMDRS neck scores at the 13.9‐month follow‐up after unilateral pallidothalamic tractotomy. The pallidothalamic tract in Forel's field H1 is expected to be an alternative treatment target for cervical dystonia.