Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy of the upper extremity [1]. Patients with CTS may have different pain sensations. [2]. There is rising interest in the genetic predisposition to the painful conditions as they may be helpful in explaining the different pain responses to the same painful stimuli [3]. Three single nucleotide polymorphisms (SNPs) were accepted to impact pain perception: catechol-O-methyltransferase (
The COMT is an enzyme that metabolizes catecholamines such as dopamine, norepinephrine or epinephrine and has been reported to participate in the pathogenesis of several neuropsychiatric disorders [6]. The
Ninety-five patients with CTS and 95 age- and ethnicity-matched healthy controls were enrolled in this study. All the participants were women and housewives. Informed consent from the all participants were obtained before being admitted to the study. The study was approved by the local ethics committee.
Patients were excluded from this study if they had any of the following: having previously undergone surgery for CTS, any sensory or motor deficit in the ulnar nerve, multiple diagnosis of the upper extremities such as lateral epicondylitis or cervical radiculopathy, history of systemic disease that causes CTS such as diabetes mellitus or hypothyroidism, concomitant systemic musculoskeletal conditions such as rheumatoid arthritis or fibromyalgia, pregnancy, previous fracture of the bones of upper extremities, trauma of the neck, shoulder or upper extremities and any other neurologic diseases. The patients had to have at least four of the following to be enrolled to undergo electroneurography (ENG): pain and paresthesia in the median nerve distribution without extra median nerve territory symptoms for at least six months; increasing symptoms at night; positive Tinel sign; positive Phalen sign and self-reported hand strength deficits. The age, gender, body mass index (BMI), symptoms duration and dominant hand of the patients were recorded. Tinel and Phalen signs were noted as positive or negative.
Functional and clinical status linked to CTS was evaluated by the Turkish version of the Boston Questionnaire that consists of the symptom severity scale (SSS) and the functional status scale (FSS). The SSS and the FSS include 11 and eight questions, respectively, which are scored with one (mildest) to five (most severe) points. The overall score is the mean of 11 scores assessing pain severity, numbness and weakness at night and day and eight scores assessing the difficulty in performing common hand-related tasks. Higher scores indicate worse symptoms or dysfunction [10]. The intensity of hand or wrist pain in the last 2 weeks was rated on VAS as cm by the patients.
Electroneurography (ENG) was performed with a two-channel ENG system (Micromed S.p.A., Mogliano Veneto TV, Italy) by an experienced physician when the patient was sitting with her arm semi-flexed. Electroneurography comprised motor and antidromic sensory conduction velocities of the median and ulnar nerves. Severity of the ENG was also classified according to standardized guidelines of the American Association of Electrodiagnosis, the American Academy of Neurology and the American Academy of Physical Medicine and Rehabilitation [11]. If median nerve sensory conduction velocity is less than 40 mm/s and median nerve distal motor latency is greater than 4.20 ms, they were considered to be abnormal. Only patients with abnormal segmental comparative tests were classified to have minimal CTS, while individuals with abnormal median nerve sensory velocity conduction and normal distal motor latency were considered to have mild CTS. To have moderate CTS, ENG has to reveal both abnormal median nerve sensory velocity conduction and distal motor latency. The patients who have abnormal median nerve motor distal latency and do not have median nerve sensory response are accepted to have severe CTS. Sensory and motor nerve conduction studies of the ulnar nerve were performed in order to rule out ulnar nerve lesions.
Blood samples from both patient and control groups were collected in vacutainers containing EDTA as anticoagulant. We isolated DNA according to the procedures of the DNA isolation kit used (Gentra Puregene Blood Kit; Qiagen GmbH, Hilden, Germany) and samples were stored at ‒20 °C until analyzed by polymerase chain reaction (PCR).
The
Data were analyzed using the Statistical Package for the Social Sciences (SPSS) software version 15.0 for Windows (SPSS Inc., Chicago, IL, USA). Mean and standard deviations (mean ± SD) were used for the presentation of continuous quantitative variables. Frequencies and percentages were used for categorical data. The one-way analysis of variance (ANOVA) test was used for parametric variables, and for non parametric variables, the Kruskal-Wallis test was used for comparisons among the three groups. For evaluation of categorical variables, a χ2 test and if needed, Fisher’s exact
The ages of the patients and the healthy controls were 46.3 ± 12.0 and 46.8 ± 11.3 years, respectively (
The
Distribution of the
Parameters | Women with CTS ( | Healthy Controls ( | |
---|---|---|---|
Met/Met | 5 (5.3%) | 2 (2.1%) | |
Val/Met | 60 (63.2%) | 65 (68.4%) | 0.460 |
Val/Val | 30 (31.6%) | 28 (29.5%) | |
Alleles | |||
Met | 70 (41.9%) | 69 (41.9%) | |
Val | 120 (58.1%) | 121 (58.1%) | 0.915 |
Val: valine; Met: methionine; CTS: carpal tunnel syndrome.
Demographic and clinic features in women with the carpal tunnel syndrome according to the
Parameters | Met/Met | Val/Met | Val/Val | |
---|---|---|---|---|
Age (years) | 40.7±12.3 | 47.0±11.6 | 46.3±11.5 | 0.418 |
BMI (kg/cm2) | 27.5±5.6 | 29.6±4.8 | 29.4±5.5 | 0.312 |
Symptom duration (months) | 54.0±84.2 | 28.5±23.0 | 33.8±46.5 | 0.303 |
Severity of pain (cm) | 8.0±2.7 | 7.4±3.2 | 6.3±4.0 | 0.392 |
Severity of ENG (mild/moderate/severe) | 2/2/1 | 26/28/6 | 19/10/1 | 0.347 |
Tinel sign (N/P/PP) | 0/4/3 | 3/21/14 | 2/35/13 | 0.572 |
Phalen sign (N/P/PP) | 0/5/3 | 3/20/14 | 2/35/13 | 0.551 |
Boston FSS | 1.8±0.9 | 2.5±3.0 | 2.1±1.0 | 0.530 |
Boston SSS | 2.8±1.4 | 2.9±0.9 | 2.8±0.9 | 0.986 |
CTS: carpal tunnel syndrome; Met: methionine; Val: valine; BMI: body mass index; ENG: electroneurography; N: bilateral negative; P: unilateral positive; PP: bilateral positive; Boston FSS: Boston functional status scale; Boston SSS: Boston symptom severity scale.
Lower
The
Similar to a recent study, we did not find any relationships between the
There are several limitations in the present study. The population in this study includes only female patients and the participants were all from a secondary hospital. These conditions may limit the results to the general population. Moreover, only one SNP of the
In conclusion, we found no relationships between the
The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.