Study design:
This case-control study was conducted at a neurophysiology outpatient clinic and general outpatient clinics at Al-Assad teaching hospital in Damascus, Syria. This study was conducted from December 2020 to June 2021. Interviews based on questionnaires were used to collect data after applying the inclusion and exclusion criteria for either the cases and controls. The interviewers were trained and aimed to facilitate data collection and explain any vague information in the questionnaires and to overcome any educational or cultural barrier that might have prevented proper understanding.
Study population:
Cases were at least 18 years old, able to give informed consent, and were diagnosed with CTS by a combination of clinical features, physical examination, and NCS findings. We excluded cases who had either a neuropathy other than CTS such as ulnar neuropathy or previous CTS surgery during the last year. Cases were frequency matched with a control group by gender and age (not more than 10 years range). Controls were selected from the general outpatient clinics at Al-Assad University Hospital provided that they had no history of previous or current nerve entrapments and did not need neurology symptoms or referrals. Any case or control who had conditions causing chronic pain was excluded other than the pain from CTS in case group.
Questionnaires:
Questionnaires included demographics such as gender, age, educational level, work, marital status, number of children, along with handedness and shisha or cigarette smoking.
The evaluation of patients with suggestive CTS symptoms was made through taking a detailed history of their condition, performing clinical examination which includes Phalen and Tinel tests, and finally confirming the diagnosis by conducting NCS.
CTS symptoms severity was assessed by asking cases to complete the Arabic version of Boston carpal tunnel questionnaire (BCTQ-A). Boston carpal tunnel questionnaire (BCTQ) is a self-report questionnaire that records symptom severity and functional status in CTS patients (9). It represents CTS severity in the last 2 weeks and consists of two scales; the first one is the symptom severity scale (SSS) that has 11 items that cover 6 domains include: pain, numbness, nocturnal symptoms, paraesthesia, weakness, and functional status. Its score ranges from 1 to 5 which is the most severe. The second one is functional status scale (FSS) that has 8 functional activities that are commonly affected by CTS (difficulty in writing, buttoning clothes, opening jars, holding a book, gripping a telephone handle, performing household chores, carrying grocery bags, bathing, and dressing). The scores also range from 1 to 5 which represents not being able to perform the activity at all (10). Since many patients were illiterate, we had to change the question asking about difficulties of writing or holding a book while reading to difficulties of using cutlery during their meals or holding their plate while eating, respectively.
Hospital Anxiety and Depression Scale (HADS) was also used which is a brief, clinically meaningful scale that screens for the levels of anxiety and depression in clinics. The limitation of this version that it does not have somatic symptoms of depression to reduce the effect of the current medical condition(s) on the scores. It consists of two subscales and scores can predict the psychosocial and physical outcomes. HADS has 14 items as anxiety and depression has 7 items each. Each item scored on a four-point scale ranging from 0 to 3 and the maximum score for each subscale is 21. Scores that range from 0- 7 are considered normal while 8-10 are considered borderline, and 11-21 are considered as anxiety or depression cases (11, 12).
Dimensions of Anger Reactions Scale-5 (DAR-5) is used to assess for problematic anger. It is a mini screening measure of anger reactions for the past 4 weeks. It assesses frequency, intensity, and duration of anger, antagonism toward others, and social relations interference. Scores of each item range from 1 (None or almost none of the time) to 5 (All or almost all of the time). Total scores above 12 are considered as problematic anger (13, 14).
Nerve Conduction Studies (NCS): Median distal motor latency (DML) and median sensory NCS (between the wrist and digit, between the wrist and palm) are of the best NCS tests to evaluate CTS according to a literature review of the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) (8). Of these tests, distal motor latency (DML) and distal sensory latency (DSL) are the most popular ones so that we used them along with other tests such as sensory nerve conduction velocity (NCV) and amplitude in order to increase the sensitivity and specificity of our tests. The sensory conduction study was performed by placing an active electrode on the index at a distance of 13-14 cm from a stimulator in the middle of the wrist. We also stimulated the median nerve at the palm. While the motor conduction study was done by placing an active electrode on the belly of the abductor pollicis brevis (APB) muscle. We stimulated the median nerve at the wrist at a distance of 4-6 cm from the active electrode.
Neurophysiological grading of CTS was done based on the study of (Bland, 2000) (5, 15) :
Grade 0: normal (absence of abnormal neurophysiological findings)
Grade 1: very mild (NCV from index to wrist < 50m/s and ≥ 40 m/s, DML from wrist to abductor pollicis brevis [APB] > 4.0 ms)
Grade 2: mild (NCV from index to wrist < 40 m/s, DML [APB] < 4.5 ms)
Grade 3: moderate (DML [APB] > 4.5 ms and < 6.5 ms with normal index finger sensory nerve action potential [SNAP])
Grade 4: severe (DML [APB] > 4.5 ms and < 6.5 ms with absent index [SNAP])
Grade 5: very severe (DML [APB] > 6.5 ms)
Grade 6: extremely severe (motor nerve action potential (MNAP) [APB] < 0.2 mV)
Definitions:
The classification of clinical symptoms such as numbness, tingling or pain depended on the location where the patient experiences these symptoms. It comprised 4 categories: classic, probable, possible, and unlikely which represent the following patterns of symptoms: two of three fingers (thumb, index, and long) without involvement of the palm or hand dorsum, two of three fingers (thumb, index, and long) and the palm but no confinement to the ulnar side, one of three fingers (thumb, index, and long), and none of three fingers, respectively (8, 16).
Tinel’s test result is considered positive if patients display CTS symptoms while the examiner is percussing the median nerve over the along the carpal tunnel (3, 8). In comparison, the result of Phalen’s manoeuvre by which patients flex the wrist vertically is described as positive if the patient experiences symptoms in the distribution of the median nerve (3, 8).
Statistical analysis:
Statistical analysis was performed using the Statistical Package for Social Science (SPSS 25). Descriptive statistics were stated as the mean and standard deviation, frequency and percentage. Chi-square test (or exact test) were performed for comparing categorical data and Student’s t-test or one-way analysis of variance (ANOVA) for continuous variables as appropriate. Pearson’s correlations were used to evaluate relationships between variables. A p-value of less than 0.05 was considered significant.
Ethics:
The study was approved by the local ethics committee of Damascus University, faculty of medicine.