F-wave parameters and body mass index in carpal tunnel syndrome

The Effect of Body Mass Index on Open Carpal Tunnel Release Recovery

Purpose

The purpose of this study was to determine whether a relationship exists between body mass index (BMI), specifically obesity, and surgical outcomes for open carpal tunnel release. Obesity is correlated with increased incidence of carpal tunnel syndrome; however, the effect of obesity on after release recovery has not been examined.

Methods

This study used a retrospective review of patient charts (n = 142). BMI was calculated based on height and weight measurements, and patients were grouped based on their BMI into the following categories: healthy BMI (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), obesity class one (30-34.9 kg/m2) (OB1), obesity class (2 35-39.9 kg/m2) (OB2), or obesity class three (40+ kg/m2) (OB3). Data were then complied on surgical outcomes by assessing preoperative pain, postoperative pain at 2 and 6 weeks, postoperative joint stiffness, wound healing time, and infection status. Data were analyzed using chi-square analyses and multivariable logistic regression to assess the differences in treatment outcomes while controlling for possible confounding variables.

Results

Age at the time of release was found to be inversely correlated with BMI. Healthy BMI patients (n = 19) underwent release at an average age of 59.1 years, whereas OB3 (n = 30) underwent release at an average age of 46.9 years. The odds of improvement in pain were significantly lower in all three obesity groups when compared with healthy BMI at both 2 and 6 weeks after operation.

Conclusions

Our results indicate that obesity may be positively correlated with earlier incidence of carpal tunnel syndrome requiring surgical intervention. These data also indicate the increased rates of postoperative complications in obese patients, particularly patients with OB3. Patients with OB3 need to understand these risks before undergoing open release. Further study should examine the impact of type 2 diabetes on carpal tunnel release recovery.

Clinical relevance

The information included in this study may be used to guide surgeons and patients when considering the effect and potential improvement in outcomes that may come from addressing patient BMI before open carpal tunnel surgery.

F-wave parameters and body mass index in carpal tunnel syndrome

BACKGROUND

Severe carpal tunnel syndrome (CTS) readily lends itself to both clinical and electrophysiological recognition. The uncertainty sometimes is in identifying and quantifying motor involvement in mild and, perhaps, in moderate CTS. Our study aimed to evaluate F responses in mild and moderate CTS and determine the contribution of BMI to the F-wave parameters.

METHODS

A retrospective review of the clinical and electrophysiological data of patients with CTS seen at the clinical neurophysiology laboratory of Aga Khan Hospital, Dar es Salaam, between 1 August 2017 and 31 July 2019 was retrieved. Carpal tunnel syndrome was graded according to the electrophysiological criteria of Padua. The F-wave parameters of patients with mild-to-moderate CTS were analyzed and compared with asymptomatic controls.

RESULT

We studied 91 hands. Twenty-two hands were asymptomatic controls, 30 hands had mild CTS, and 39 hands had moderate CTS. Patients with moderate CTS were more obese (p =.011), had more females (p =.044), and were older (p= <0.001). F-wave parameters were not convincingly different between mild and moderate CTS. F-wave chronodispersion (p =.035) and F-wave persistence (0.019) were significantly different between nonobese control and mild and moderate CTS. Median-ulnar F-wave latency difference (FWLD) was significant between obese patients with mild CTS and moderate CTS scores (p =.017).

CONCLUSION

Although a clear difference exists between F-wave parameters in asymptomatic controls and those with CTS, the F-wave study is inadequate in distinguishing mild and moderate CTS even in the context of BMI. Median-ulnar F-wave latency difference (FWLD) appeared to be a promising discriminant parameter between obese patients with mild CTS and those with moderate CTS.