KEY WORDS
Carpal tunnel syndrome - disabilities of arm - shoulder and hand score - electromyography
nerve conduction velocity - Levine score
INTRODUCTION
Carpal tunnel syndrome (CTS) is an important cause of pain, neurological symptoms
and functional limitation of the hand. In fact, it is the most common cause of nerve
compression of upper extremity according to data from the USA.[1] In the large majority of cases, the condition is idiopathic. CTS has a significant
impact on individual well-being and economic activity.
Despite many scientific papers and publications, there is no unanimity regarding diagnostic
criteria for CTS. Usually clinical symptoms and physical signs are helpful in making
provisional diagnosis. Person-to-person variability in severity of signs and symptoms
suggestive of CTS makes it more difficult to diagnose and manage patients suffering
with CTS. Levine et al. have developed a self-administered questionnaire for assessing the severity of the
CTS symptoms.[2]
Besides history and clinical examination, electrophysiological examination is the
only reliable means of confirming CTS. Electrophysiological examination is highly
specific and is reasonably sensitive in diagnosing CTS.[3]
[4] It helps rule out other neuropathic and co-morbid conditions as a cause of the signs
and symptoms seen in the patient.
This study was undertaken to analyse the relationship of clinical severity within
various modified Padua's groups of electrophysiological severity of CTS and its impact
on post-operative recovery and relief. This study is an effort to enhance our knowledge
for categorising patients depending on the severity of CTS so that we can form clinical
guidelines which will be helpful for us in predicting the extent of post-operative
recovery and relief.
PATIENTS AND METHODS
All patients diagnosed with CTS and fulfilling inclusion and exclusion criteria (as
below) were included in the study. The present study was a prospective study, which
included 35 patients (31 females and 4 males). Patients presenting to the Department
of Hand and Plastic surgery with typical hand symptoms such as pain, tingling and
numbness and nocturnal sleep disturbance with paraesthesia were selected for the study
after providing informed written consent.
The clinical examination of the patients consisted of history, physical examination
and specific provocative tests on the hand. Baseline data such as name, age and gender
were recorded for all the patients included in the study. Height and weight of all
patients were also noted down. Body mass index (BMI) was calculated for all patients.
The presence of co-morbid conditions such as diabetes mellitus and hypothyroidism
was noted. The patient was also physically examined for various findings supporting
the diagnosis of CTS. Thenar muscle atrophy was looked for. Provocative tests such
as Phalen's sign, Tinel's signs and Durkan's tests were elicited and findings were
noted down. Median nerve innervated area was examined for sensory evaluation and condition
of the skin. The patient was examined to rule out other causes of hand symptoms such
as cervical spondylosis or generalised diabetic neuropathy. Objective assessment of
the motor power of median nerve was done by recording grip strength. A special note
was taken about duration of symptoms, whether symptoms were present in one or both
hands, handedness and profession of the patient. A visual analogue scale[5] was used to make a subjective assessment of the patient's complaints. This is in
[Figure 1]. A self-administered questionnaire formed by Levine et al.[2] was introduced to obtain symptom severity score (SSS) and functional status score
(FSS). Disabilities of arm, shoulder and hand (DASH) questionnaire[6] was also used for patient's assessment.
Figure 1: Visual analogue scale[5]
Electrophysiological evaluation of each patient was done pre-operatively, from the
Department of Neurophysiology in our hospital to avoid inconsistency in comparing
values attributed to machine or operator. Readings of sensory nerve action potential
(SNAP) (in μv), peak amplitude of compound muscle action potential (in mV), peak latency
of SNAP (in ms) and conduction velocity of the SNAP (in m/s) were recorded. According
to Padua's classification,[7] patients were divided into five groups, namely, minimal, mild, moderate, severe
and extremely severe CTS. For statistical convenience and significance, we modified
this classification into three groups, namely, minimal to mild (Group I), moderate
(Group II) and severe to extreme (Group III).
Except for electromyography (EMG) nerve conduction velocity (NCV) the whole assessment
was repeated at follow-up at 3 months post-operatively. EMG NCV was not done at 3
months as it does not reliably show a change so quickly. The exact timing of improvement
is not documented clearly, but it can take as long as 42 weeks for sensory latencies.[8] Hence, EMG NCV may not be a reliable indicator of nerve recovery if done at 3 months
when we had called all our patients for a review.
Inclusion criteria
-
All patients presenting to the Department of Plastic Surgery in our institute with
hand symptoms such as pain, tingling and numbness and nocturnal sleep disturbance
with paraesthesia
-
All patients who were diagnosed with CTS on electrophysiological studies.
Exclusion criteria
-
Patients who refused consent to take part in study
-
All patients with generalised neuropathies or double crush syndrome were excluded
from the study.
Variable and outcome measures
To summarise, the following data of each patient were recorded for comparison before
and after surgery
-
Visual analogue score (pre- and post-operative)
-
SSS (pre- and post-operative)
-
FSS (pre- and post-operative)
-
DASH score (pre- and post-operative).
These data were studied to analyse the correlation with the following electrophysiological
variables of median nerve:
-
SNAP (in μv)
-
Peak latency of SNAP (in mS)
-
Conduction velocity of the SNAP (in m/s)
-
Peak amplitude of compound muscle action potential (in mV)
-
Peak latency of motor nerve action potential (in mS).
Data analysis
After data collection, data entry was done in Excel. Data analysis is done with the
help of SPSS Software ver 15 and SigmaplotVer 11 (Systat Software Inc. San Jose, California,
USA).
Quantitative data are presented with the help of mean, standard deviation (SD), median
and interquartile range, comparison among study group is done with the help of Mann–Whitney
test or unpaired t-test, intragroup comparison is done with the help of one-way analysis of variance
or Kruskal–Wallis test as per results of normality test and multiple pair-wise comparison
among group is done with Tukey's test or Holm–Sidak method.
Qualitative data are presented with the help of frequency and percentage table and
association among study group is assessed with the help of Chi-square test.
P < 0.05 is taken as significant level.
All patients were managed with surgical treatment. At our institute, we employ minimal
invasive open technique for carpal tunnel release.[9]
RESULTS
In our study, majority of the patients were in the fourth, fifth and sixth decades
of their life, and maximum 13 patients were in fifth decade with the mean age of 47.34
(SD 4.95) years and median of 47 years.
Thirty-three patients with 35 hands suffering from CTS were studied in the present
study. It included 30 females and 3 males. Only one patient out of the 33 was left-hand
dominant. Among the 35 affected hands, the right hand was affected 27 times (77.1%).
Almost 75% (26) of patients were homemakers, whereas a few patients were artist, dentist
or staff nurse who were required to perform skilled job and other patients were white-collar
workers having clerical work, computer job, trader and teacher.
We classified our patients according to BMI. Patients with BMI 19–24 were considered
to have appropriate weight for height. The groups were underweight (BMI <19), overweight
(BMI 24–30), obese (BMI 30–40) and morbidly obese (BMI >40). Only 28.6% (10) of the
patients had appropriate weight for their height, whereas 20 of the 35 patients were
overweight and 5 patients were obese. The Tinel's sign was positive in 27 (77.14%)
patients. Phalen's test was positive in 30 (85.71%) out of 35 patients, whereas the
Durkan's sign was positive in 30 (85.71%) patients. On motor examination of all patients,
68.6% of patients were found to have thenar muscle atrophy on presentation.
According to modified Padua's classification, there were five patients who were falling
in Group I of CTS, whereas 23 and 7 patients were observed to be in Group II and III,
respectively [Table 1].
Table 1
Distribution of patients according to modified Padua's classification
|
Electrophysiological severity
|
Frequency (%)
|
|
Group I
|
5 (14.3)
|
|
Group II
|
23 (65.7)
|
|
Group III
|
7 (20.0)
|
|
Total
|
35 (100.0)
|
The mean clinical severity scores were as shown in [Table 2].
Table 2
Clinical severity scores: Pre- and post-operative
|
Score (minimum–maximum)
|
Mean (SD)
|
|
Pre-operative score
|
Post-operative score
|
|
VAS: Visual analogue scale, SSS: Symptom severity score, FSS: Functional status score,
DASH: Disabilities of arm, shoulder and hand, SD: Standard deviation
|
|
VAS (0-10)
|
7.29 (1.58)
|
0.94 (1.55)
|
|
SSS (0-44)
|
25.54 (9.06)
|
3.20 (6.57)
|
|
FSS (0-32)
|
18.89 (8.96)
|
2.00 (4.52)
|
|
DASH (30-150)
|
82.89 (19.31)
|
34.74 (10.84)
|
The mean values of various electrophysiological parameters studied with the SD in
the modified Padua's groups were as shown in [Table 3].
Table 3
Comparison of electrophysiological scores in Padua's modified groups
|
Group
|
Mean (SD)
|
|
SNAP
|
Sensory latency (ms)
|
Sensory conduction velocity (m/s)
|
CMAP (mV)
|
Motor latency
|
|
SNAP: Sensory nerve action potential, CMAP: Compound muscle action potential, SD:
Standard deviation
|
|
Group I
|
17.95 (5.37)
|
2.54 (0.55)
|
49.34 (7.79)
|
15.15 (1.29)
|
3.61 (0.46)
|
|
Group II
|
8.32 (6.17)
|
3.64 (1.50)
|
35.85 (6.56)
|
11.47 (4.81)
|
5.24 (2.04)
|
|
Group III
|
1.50
|
9.08
|
28.3
|
4.36 (3.47)
|
7.99 (3.34)
|
The change in the clinical severity score from pre-operative value to the post-operative
value should indicate clinical improvement or deterioration. Hence, we compared the
difference between pre-operative and post-operative scores (pre- and post-operative)
in the three electrophysiological severity groups.
The difference between the pre- and post-operative scores was compared to analyse
clinical post-operative recovery. All the scores showed statistically proved significant
improvement on post-operative evaluation as shown in [Table 4].
Table 4
Comparison of difference between pre- and post-operative scores in Padua's modified
groups
|
Group
|
Score (pre- and post-operative), mean (SD)
|
|
VAS
|
SSS
|
FSS
|
DASH
|
|
VAS: Visual analogue scale, SSS: Symptom severity score, FSS: functional status score,
DASH: Disabilities of arm, shoulder and hand, SD: Standard deviation
|
|
Group I
|
6.20 (1.48)
|
23.60 (12.97)
|
14.40 (7.96)
|
47.40 (23.10)
|
|
Group II
|
6.43 (2.46)
|
22.43 (10.03)
|
17.52 (10.52)
|
47.30 (21.69)
|
|
Group III
|
6.14 (1.77)
|
21.14 (7.80)
|
16.57 (9.16)
|
51.43 (19.51)
|
DISCUSSION
In the present study, we compared pre-operative clinical severity scores with their
respective post-operative values. We found that the clinical severity scores are statistically
significantly improved after surgery [Table 5]. It indicates not only that surgery is the effective mode of treatment but also
that the clinical severity scores, namely, visual analogue score, SSS, FSS and DASH
score are very much predictive of the success of surgery and recovery of patient from
the symptoms of CTS the patient was suffering from before surgery.
Table 5
Comparison of preoperative with postoperative scores
|
Score
|
Pre-operative
|
Post-operative
|
Wilcoxon test
|
P
|
Significance
|
|
VAS: Visual analogue scale, SSS: Symptom severity score, FSS: functional status score,
DASH: Disabilities of arm, shoulder and hand
|
|
VAS score
|
7.29
|
0.94
|
5.173
|
<0.001
|
Difference is significant
|
|
SSS
|
25.54
|
3.2
|
5.129
|
<0.001
|
Difference is significant
|
|
FSS
|
18.89
|
2
|
5.022
|
<0.001
|
Difference is significant
|
|
DASH score
|
82.89
|
34.74
|
5.144
|
<0.001
|
Difference is significant
|
We also compared various electrophysiological parameters in the three severity groups
to find that various electrophysiological parameters are effective in making diagnosis
of CTS, especially when the patient is suffering from severe to extremely severe CTS.
You et al.[10] studied the relationship between pre-operative clinical severity scales and abnormal
electrodiagnostic measures in CTS patients. You et al. used the same Levine questionnaire which was also used in the present study. They
found significant relationships between the clinical scales and nerve conduction measures.
In the present study, we compared the difference between pre-operative and post-operative
SSS which is obviously an indicator of recovery from the symptom complex the patient
was suffering from.
On comparing the difference between pre-operative and post-operative SSSs among the
three study groups, we have made depending on the Padua's classification, we could
not establish significant difference (P > 0.05). Hence, we cannot predict post-operative clinical severity scores and in
turn the extent of recovery just by knowing pre-operative CTS severity on pre-operative
electrophysiological evaluation.
Similar results were obtained on comparing the difference between other scales used
in the present study, namely, visual analogue scale, FSS and DASH score. Significant
difference was not found on statistical evaluation (P > 0.05).
Schrijver et al.[11] studied 138 patients with completed Levine questionnaire and nerve conduction studies
(NCS) before and after treatment to correlate NCS and clinical outcome measures but
could not identify any relationship between pre-operative NCS and the outcome of the
surgery, which was also similar to the results of Longstaff et al.[12]. Schrijver et al. also studied the relationship between nature or duration of symptoms and severity
of electrophysiological impairment. They also concluded that EMG NCS cannot be considered
essential in assessing outcome in CTS after surgery.
Khan et al.[13] compared subjective symptoms with psychological factor as well as with electrophysiological
severity, and they concluded that subjective symptoms are more correlated with psychological
factors than with objective electrophysiological severity of the disease. They even
suggested antidepressant drugs in select patients as a treatment apart from analgesics.
CONCLUSIONS
The aim of the study was to study the various clinical and electrophysiological parameters
of severity of CTS and to see if the severity of CTS predicts recovery after surgery.
The various clinical severity scores can be effectively used to assess patient's post-operative
recovery from symptoms, but these scores fail to predict the extent of recovery the
patient will have after surgery just by knowing the pre-operative scores. The difference
between pre-operative and post-operative scores is a good indicator of post-operative
recovery, but it does not show any correlation when compared with electrophysiological
severity. Our study reconfirms the diagnostic role of EMG NCV in CTS, but the electrophysiological
severity does not always match the clinical severity. Our study showed that there
is no definitive relation between electrophysiological severity and the clinical severity
scores.
Hence to summarise, from our study, we can draw the following conclusions:
-
Clinical scores are good to know as a marker of clinical severity of CTS and also
as a baseline value to compare with post-operative clinical scores
-
There is no definitive relationship between clinical and electrophysiological severity
of CTS
-
Difference between the pre-operative and post-operative clinical severity scores is
a good indicator of post-operative recovery
-
Pre-operative scores alone fail to predict the extent of post-operative recovery from
the symptoms.
Hence, clinical correlation is the only foolproof way to predict severity and improvement
after surgery in CTS-affected patients.
Financial support and sponsorship
Nil.
