Weight loss in obese patients, however, does not bring relief of the syndrome. Experts suggest a genetic link between the two conditions, or a genetic profile that pre-disposes a patient to both conditions.

Looked at purely on the level of symptoms, there would appear to be a clear link between obesity and carpal tunnel syndrome. Whereas 10% of the general population is likely to suffer carpal tunnel syndrome at some point in their life, 25% of people classifiable as obese have the condition. Carpal tunnel syndrome is the most common nerve disorder causing disability. It is a condition in which the median nerve is compressed where it runs through the carpal tunnel at the wrist. Squeezing of the nerve can occur because the canal narrows, or because tendons running through the same route increase in size. Carpal tunnel syndrome can cause a burning or tingling sensation in fingers and thumb, numbness, difficulties gripping objects and weakness in the hand. Symptoms usually gradually increase over time. Those afflicted with the syndrome often have to cope with poor hand function and significant pain.

A study undertaken by Dr Yuksel Kaplan and his colleagues at Gaziosmanpasa University in Turkey, has investigated the role of obesity as a risk factor in this debilitating nerve condition. Although obesity is linked to a higher prevalence of carpal tunnel syndrome, it does not appear to be causative, the team of researchers reported at the 17th Meeting of the European Neurological Society from June 16 to 20 in Rhodos (Greece).

The study assessed the effect of weight loss in very overweight patients on transmission of impulses along the median nerve (nerve conduction). Those selected for the study suffered mild to moderate impairment in hand function from carpal tunnel syndrome. All were classifiable as obese, which is to say they had a body mass index of 30 or over. A normal body mass index is 20 to 25, 25 to 30 is regarded as overweight, and over 30 as obese. All 126 patients originally included in the study were analysed as to carpal tunnel syndrome symptoms, age, gender, height, body weight and concomitant diseases. Initial nerve conduction studies, measuring transmission of impulses along the median nerve, were conducted. Patients were then put on diet programmes. After three months, the nerve conduction studies were repeated.

Weight Loss Does Not Bring Relief “ Genetic Links Discussed92 patients were included in the second nerve conduction tests. Their ages ranged from 17 to 77 years, and the sample was overwhelmingly female (79 women to 13 men.) They showed very significant weight loss after three months of a diet programme, the body mass index dropping from an average of 36 to 26/ 27, which is to say, on average they no longer qualified as obese. However, the weight loss brought no relief in carpal tunnel syndrome, says Dr Kaplan.

The study clearly shows that, contrary to expectations based on the higher prevalence of carpal tunnel syndrome among the obese, weight loss in obese patients does not bring relief of the syndrome. Thus the nature of the link between excess body weight and a higher than average incidence of carpal tunnel syndrome remains to be explained. While purely speculative, Dr Kaplan has suggested a genetic link between the two conditions, or a genetic profile that pre-disposes a patient to both conditions.

Squarer shaped Wrist Pre-disposes to Carpal Tunnel Syndrome Some light may be thrown on the problem by a study completed at the Emam Khomeini hospital in Tabriz in Iran. Doctors M. Yazdchi Marandi and M. Sharifi presented a study at the ENS meeting examining the role of size and proportions of the hand in the development of carpal tunnel syndrome. 131 patients with carpal tunnel syndrome were compared to cohorts free of the syndrome, over a 14 month period. Those suffering carpal tunnel syndrome were then analysed using electrodiagnostic criteria to establish different degrees of severity of symptoms. Factors such as wrist shape, hand length/height ratios and body mass index were compared between the two groups, tracking the differences in symptom severity. Results essentially confirmed current reports in the literature, that obesity and wrist shape indicate a higher prevalence of carpal tunnel syndrome, with a squarer shaped wrist pre-disposing a patient.

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