Individual Response to Botulinum Toxin Therapy in Movement Disorders: A Time Series Analysis Approach

Mapping trends in hemifacial spasm research: bibliometric and visualization-based analyses of the Web of Science Core Collection

Hemifacial spasm (HFS) is a common cranial nerve disease. In HFS research, we conducted a bibliometric analysis to examine the development and research trends. A retrieval of HFS studies published between 2011 and 2022 was performed from the Web of Science Core Collection in September 2022. Two scientometric tools were used to perform bibliometric and visualization-based analyses: VOSviewer and CiteSpace. Bibliometric analysis of 1461 studies published between 2011 and 2022 was carried out using data from 444 journals, 6021 authors, 1732 institutions, and 76 countries/regions. China, the USA, Japan, and South Korea were four key contributors to this study. Shanghai Jiaotong University was the major institution with the larger number of publications. Li Shiting was the most prolific author. Jannetta PJ was the most co-cited author. World Neurosurgery was the top prolific journal. Journal of Neurosurgery was the top co-cited journal. The top five keywords were hemifacial spasm, microvascular decompression, trigeminal neuralgia, surgery, and neurovascular compression. This study examines the research trends in global scientific research on HFS over the last decade. Researchers interested in learning more about current trends and novel research frontiers in this area can benefit from the study.

Does needle size matter? Effects of micro-hypodermic needle injections of botulinum toxin type A in patients with hemifacial spasm

INTRODUCTION

Botulinum toxin type A (BoNT/A) injections are the first-line treatment for primary hemifacial spasms (HFS), but require frequent painful injections. Although micro-hypodermic needles are commonly used for aesthetic BoNT/A injections to lessen pain and bruising, their benefits in HFS remain unclear.

OBJECTIVE

To compare side effects of BoNT/A injection, specifically pain and bruising, between primary HFS patients who received injections using micro-hypodermic needles (34-G) and those using standard needles (30-G).

METHODS

This cross-over, double-blind, randomised controlled trial involved HFS patients who received BoNT/A injections using either a 34-G or 30-G needle at two visits 12 weeks apart. Primary outcomes, pain and bruising were assessed immediately after injection using the Visual Analogue Scale (VAS) and Short-form McGill Pain Questionnaire (Thai version, SF-MPQ). Bruise assessment was also conducted one week after each injection. Secondary outcomes involved comparing efficacy of BoNT/A between the two types of needles and assessing other complications beyond pain and bruising.

RESULTS

65 HFS patients (47 women and 18 men; mean age 59.46 ± 11.48 years; mean disease duration 5.86 ± 4.16 years) were included in the study. Patients who received 34-G needle injections reported significantly reduced pain, as indicated by VAS, total SF-MPQ scores, and bruise scores, compared to those who received 30-G needle injections (p < 0.001, each). There were no differences in efficacy or occurrence of other complications associated with BoNT/A between the two needle types.

CONCLUSION

In HFS patients, BoNT/A injections using micro-hypodermic needles resulted in reduced pain and bruising, compared to standard needles, while maintaining similar BoNT/A benefits.

Improving the Efficacy of Botulinum Toxin for Cervical Dystonia: A Scoping Review

Cervical dstonia (CD) is a chronic disorder with a significant detrimental impact on quality of life, requiring long-term treatment. Intramuscular injections of botulinum neurotoxin (BoNT) every 12 to 16 weeks have become the first-line option for CD. Despite the remarkable efficacy of BoNT as a treatment for CD, a significantly high proportion of patients report poor outcomes and discontinue the treatment. The reasons that drive sub-optimal response or treatment failure in a proportion of patients include but are not limited to inappropriate muscle targets and/or BoNT dosing, improper method of injections, subjective feeling of inefficacy, and the formation of neutralizing antibodies against the neurotoxin. The current review aims to complement published research focusing on the identification of the factors that might explain the failure of BoNT treatment in CD, highlighting possible solutions to improve its outcomes. Thus, the use of the new phenomenological classification of cervical dystonia known as COL-CAP might improve the identification of the muscle targets, but more sensitive information might come from the use of kinematic or scintigraphic techniques and the use of electromyographic or ultrasound guidance might ensure the accuracy of the injections. Suggestions are made for the development of a patient-centered model for the management of cervical dystonia and to emphasize that unmet needs in the field are to increase awareness about the non-motor spectrum of CD, which might influence the perception of the efficacy from BoNT injections, and the development of dedicated rehabilitation programs for CD that might enhance its effectiveness.

Baseline Variability Affects N-of-1 Intervention Effect: Simulation and Field Studies

The simulation study investigated the relationship between the local linear trend model's data-comparison accuracy, baseline-data variability, and changes in level and slope after introducing the N-of-1 intervention. Contour maps were constructed, which included baseline-data variability, change in level or slope, and percentage of non-overlapping data between the state and forecast values by the local linear trend model. Simulation results showed that baseline-data variability and changes in level and slope after intervention affect the data-comparison accuracy based on the local linear trend model. The field study investigated the intervention effects for actual field data using the local linear trend model, which confirmed 100% effectiveness of previous N-of-1 studies. These results imply that baseline-data variability affects the data-comparison accuracy using a local linear trend model, which could accurately predict the intervention effects. The local linear trend model may help assess the intervention effects of effective personalized interventions in precision rehabilitation.