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Scandinavian Journal of Pain

Official Journal of the Scandinavian Association for the Study of Pain

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Volume 18, Issue 3

Correlation of clinical grading, physical tests and nerve conduction study in carpal tunnel syndrome

Sadegh Izadi
  • Clinical Neurology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
  • Department of Neurology, Medical School, Shiraz University of Medical Sciences, Shiraz, Iran
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Bahareh Kardeh / Seied Saeed Hosini Hooshiar
  • Clinical Neurology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
  • Department of Neurology, Medical School, Shiraz University of Medical Sciences, Shiraz, Iran
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Mojtaba Neydavoodi / Afshin Borhani-Haghighi
  • Corresponding author
  • Clinical Neurology Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
  • Department of Neurology, Medical School, Shiraz University of Medical Sciences, Nemazee Hospital, Shiraz, Iran, Phone/Fax: +98-711-627-2287
  • Email
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Published Online: 2018-05-22 | DOI: https://doi.org/10.1515/sjpain-2017-0164


Background and aims

Carpal tunnel syndrome (CTS) is a common debilitating condition. As the reliability of CTS-specific physical tests and its clinical grading remain a matter of debate, we determined the correlations between these assessments with nerve conduction study (NCS).


In this cross-sectional study, patients with uni or bilateral CTS, which was confirmed in electrodiagnosis, were enrolled. Clinical grading was based on the modified criteria of the Italian CTS Study Group. Numeric Pain Rating Scale (NPRS) and Boston Questionnaire (BQ) were used. Physical tests [Phalen’s, reverse Phalen’s, Tinel’s and manual carpal compression test (mCCT)] were performed by a single blinded neurologist. A p-value<0.05 was considered statistically significant.


A total of 100 patients (age=47.48±11.44 years; 85% female) with 181 involved hands were studied. The majority of hands (59.7%) were classified as grade 2 of clinical grading. On NCS, hands with mild (64%), moderate (27%) and severe (9%) CTS were identified. Sensory (velocity, latency and amplitude) and motor parameters (latency and amplitude) were significantly correlated with clinical grades (p-value<0.001). The correlation of NPRS (p-value=0.009) and BQ (p-value<0.001) scores with NCS was significant. None of the physical tests were significantly correlated with NCS in terms of result or duration (p-value>0.05).


We found that physical tests are not a reliable screening method for evaluation of CTS severity. However, the BQ and clinical grading can be more valuable due to their significant correlation with NCS.


Physicians might benefit from employing clinical grading and BQ in practice for better assessment of CTS severity.

Keywords: carpal tunnel syndrome; clinical decision-making; diagnosis; electrodiagnosis; physical examination

1 Introduction

Carpal tunnel syndrome (CTS) is the compression neuropathy of median nerve at wrist level, where it passes through a narrow osteo-fibrous canal, and remains the most common entrapment neuropathy [1]. The prevalence of this disabling condition is estimated to range from 2.7% in general population [2] to 7.8% among employees who perform hand-intensive activities [3]. A variety of mechanical and medical risk factors contribute to the development of CTS [4], [5]. Accurate and timely diagnosis is the key to achieving the best possible outcome.

Initially, a precise history should provide the clinician with useful information about symptom onset, timing (diurnal vs. nocturnal), localization, aggravating and alleviating factors, predisposing factors, and patient’s routine working activities [6]. Presence of pain, paresthesia, and weakness, particularly within median nerve distribution, should raise suspicion about nerve damage [7]. In a precise physical examination, positive signs should be sought and other concomitant conditions should be ruled out. Commonly used provocative tests in clinical settings are Phalen’s test, reverse Phalen’s test, Tinel’s sign, Durkan’s test or carpal compression and the tourniquet test [8]. Feeling of paresthesia in the median nerve distribution within 1 min implies positive test [9].

As patient history and isolated physical tests have limited diagnostic value [10], [11], [12], paraclinical studies are essential in establishing the definite diagnosis. Nerve conduction study (NCS), ultrasound [13] and magnetic resonance imaging [14] are routinely used. NCS is the gold standard tool for diagnosis and quantification of the severity of CTS [15]. Although ultrasound may not replace NCS as the most sensitive and specific test, it is a feasible first-line confirmatory alternative [16].

The correlation between CTS-specific physical tests and clinical grades of CTS with NCS remains uncertain. Determining the reliability of these simple and low-cost methods helps physicians obtain a more accurate diagnosis and plan optimal treatment. With this aim, we designed the present study.

2 Materials and methods

2.1 Patients and setting

This cross-sectional study was conducted on a sample of consecutive patients referring to our outpatient neurology clinic between 2016 and 2017 (affiliated with Shiraz University of Medical Sciences, Shiraz, Iran), who had uni or bilateral CTS confirmed in NCS. Exclusion criteria were proximal involvement of median nerve, compression of ulnar nerve, as well as any underlying neuropathies.

2.2 Nerve conduction study

Neurophysiological evaluation was performed using a commercially available Medelec Oxford Synergy equipment (Old Woking, Surrey, England). Firstly, it was ensured that the skin temperature was above 33 °C. If colder, the hands were warmed up to a suitable temperature. Afterwards, the surface electrodes were utilized for stimulation and recording of the median sensory and motor amplitude, velocity and latency. For sensory nerve conduction, the antidromic technique was applied. The sensory delay was recorded with stimulating electrodes placed at wrist and recording electrodes placed at 3rd finger. Motor conduction studies were carried out using bipolar surface stimulating electrodes.

Based on the findings of NCS, we classified CTS severity as follows: (a) mild: distal sensory latency >3.5 ms with normal motor study; (b) moderate: abnormal sensory study and distal motor latency between 4.4 and 6.5 ms and (c) severe: abnormal sensory study and distal motor latency >6.5 ms with or without decreased motor amplitude [17].

2.3 Data gathering

Demographic characteristics of patients including age, gender and occupation were recorded and related medical profile was assessed. Subsequently, a single neurologist, who was blinded to the results of NCS, carried out subjective and objective investigations for each individual. The neurologist inquired the patients about clinical manifestations; such as, pain, paresthesia, or numbness. Numeric Pain Rating Scale (NPRS) was used to measure pain intensity. Using this information and according to the modified criteria of the Italian CTS Study Group [18], [19], [20], involved hands were classified into the following clinical grades: grade 0: asymptomatic, grade 1: nocturnal paresthesia, grade 2: diurnal paresthesia, grade 3: numbness and grade 4: atrophy. Grades 0 and 1 were considered as mild, grades 2 and 3 as moderate and grade 4 as severe CTS. Furthermore, Boston questionnaire (BQ) was completed. This self-administered questionnaire was first developed by Levine et al. [21], and is widely used for CTS [22], [23]. It has two parts for assessment of severity of symptoms (BQ-SS) and functional status (BQ-FS), which consist of eight and 11 questions, respectively. Rezazadeh et al. [24] has verified the validity and reliability of the Persian BQ in Iranian patients with CTS. Also, the Persian format has been shown to be a valid and reliable tool in diabetic patients [25]. Finally, the neurologist performed the following CTS-specific physical tests: Phalen’s test, reverse Phalen’s test, Tinel’s test and manual carpal compression test (mCCT). A resting time from 3 to 5 min was considered in intervals between the tests to allow for subsidence of pain induced by the previous test.

2.4 Ethical considerations

Informed written declaration of consent was obtained from each patient and data confidentiality was guaranteed. Our study was designed according to the Helsinki Declaration and approved by Ethics Committee of Shiraz University of Medical Sciences.

2.5 Statistical analysis

Data were analyzed by IBM SPSS Statistics (Chicago, IL, USA), windows version 16.0. Variables are represented as frequency (percentage) or mean and standard deviation (SD) as applicable. Kruskal-Wallis test and χ2 test were used wherever applicable. A p-value less than 0.05 was considered statistically significant.

3 Results

3.1 Demographics

Of a total of 200 hands, diagnosis of CTS was confirmed for 181 hands in NCS; at least one involved hand in each patient. The average age of patients was 47.48±11.44 (Mean±SD) years. The difference between men (50.73±13.12) and women (46.99±11.11) was not statistically significant (p-value=0.23). Female patients constituted 85% of cases. The majority of participants (60%) were housewives, 31 patients were hired in blue-collar jobs and nine had clerical occupations. Top medical comorbidities were hypothyroidism (n=14), diabetes (n=10), concomitant hypothyroidism and diabetes (n=2), and rheumatic disorders (n=6). The other 68 patients reported to be otherwise healthy.

3.2 Clinical grades

Unilateral right-sided CTS was noticed in six patients, while 13 patients had only left hand involvement. The remainder (81%) had bilateral CTS. Regarding CTS-related symptoms, 51 patients stated that they suffered from both pain and paresthesia. Fewer patients were solely affected by paresthesia (n=28) or pain (n=11). Ten patients complained of concurrent paresthesia, pain and muscular weakness. In addition, the clinical grading of CTS in involved hands is demonstrated in Figure 1. Out of 181 hands with confirmed CTS on NCS, 20 hands were asymptomatic and the patients did not have complaints about them. Therefore, these 20 hands belonged to grade 0.

Clinical grades of CTS in involved hands.
Figure 1:

Clinical grades of CTS in involved hands.

3.3 Nerve conduction study

As shown in NCS, the number of hands affected by mild, moderate and severe CTS, was 117 (64.6%), 47 (26%) and 17 (9.4%), respectively. The correlation of NCS severity with the frequency of clinical grades was investigated (Table 1).

Table 1:

The correlation of clinical grades with CTS severity based on NCS.

In addition, we evaluated the correlation of clinical grading with specific parameters of NCS (Table 2). Sensory velocity, latency and amplitude, as well as motor distal latency and amplitude were shown to be significantly different among the clinical grades (p-value<0.001).

Table 2:

The correlation of clinical grading with components of NCS.

3.4 Subjective scores

The values of NPRS and BQ were assessed in comparison to the NCS severity; both of which proved to be highly significant (Table 3).

Table 3:

The correlation of NPRS and BQ with CTS severity based on NCS.

3.5 Physical tests

There were no significant correlations between the results of physical tests and the severity of nerve compromise in NCS (Table 4). In cases with positive tests, we examined if the duration until the patient declared to feel the pain was related with CTS severity base on NCS. This item was also non-significant (Table 5).

Table 4:

The correlation of physical tests with CTS severity based on NCS.

Table 5:

The correlation of duration of positive physical tests with CTS severity based on NCS.

4 Discussion

Similar to a number of previous studies [26], [27], female gender was shown to be a risk factor in our study. The mean age of patients was in the 5th decade of life, close to the peak reported by Bland [28]. The distribution of jobs was in accordance to previous literature and is supported by an Italian study conducted by Mattioli et al., which showed that rates of surgically-treated CTS in women were highest among blue-collar workers, housewives and white-collar workers in descending order. The incidence of CTS in blue-collar men was higher than their white-collar counterparts; however, it was lower as compared to all professional groups in women. The authors pointed out, that domestic chores should be considered a potential risk factor in full-time housewives [29]. Diabetes and hypothyroidism were seen in more than a quarter of our study population. Diabetes is a well-established risk factor for CTS [30], [31], [32]. On the other hand, a recent meta-analysis showed that hypothyroidism is a weak risk factor [33].

Unsurprisingly, NPRS and BQ were highly correlated with CTS severity on NCS. Considering physical tests, we found no associations, neither in regards to the absolute positive or negative results and nor the duration to reproduce symptoms. However, it’s noteworthy that reverse Phalen’s had the lowest p-value. Dale et al. investigated Semmes-Weinstein sensory testing, Tinel’s test, and Phalen’s maneuver on a large population of 1,108 newly-hired workers in diverse industries and concluded that physical examinations have a low yield in screening for CTS [11], which is also supported in another study by Descatha et al. [10].

The relationship between various NCS parameters and clinical grading of CTS was investigated by Srikanteswara et al. Patients were divided into mild, moderate and severe CTS groups based on Mackinnson’s classification. Tinel’s and Phalen’s sign were positive in 36 (72%) and 44 (88%) patients, respectively. Although the rate for Tinel’s was similar to our findings, we only had 51% positive for Phalen’s test. The authors also mentioned that sensory conductions were more sensitive than motor conductions [34]. In contrast, Ansari et al. showed that Phalen’s 30 s was associated with electrodiagnosis [35]. In another study by Ogura et al., prolonged delays were noted in forearm sensory and motor conduction velocity, which were consistent with the increased severity of clinical grade. Yet, there were no significant differences between the severity groups [36].

5 Conclusions

Based on our findings, physical tests cannot be regarded as a valuable screening method to evaluate CTS severity. However, the BQ and clinical grading, which were highly correlated with NCS, can be more reliable.


This article was extracted from the thesis conducted by Seied Saeed Hosini Hooshiarand with the support of the dean of medical school and research vice-chancellor of Shiraz University of Medical Sciences. The authors appreciate the assistance of Dr. Laleh Khojasteh for proofreading this manuscript.


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About the article

Received: 2017-11-13

Revised: 2018-03-09

Accepted: 2018-03-14

Published Online: 2018-05-22

Published in Print: 2018-07-26

Authors’ statements

Research funding: Funded by a grant from the Shiraz University of Medical sciences (grant no. 10972).

Conflict of interest: Authors declare no conflict of interest.

Informed consent: Informed written declaration of consent was obtained from each patient and data confidentiality was guaranteed.

Ethical approval: Our study was designed according to the Helsinki Declaration and approved by the Ethics Committee of Shiraz University of Medical Sciences.

Citation Information: Scandinavian Journal of Pain, Volume 18, Issue 3, Pages 345–350, ISSN (Online) 1877-8879, ISSN (Print) 1877-8860, DOI: https://doi.org/10.1515/sjpain-2017-0164.

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