Background: The severity of carpal tunnel syndrome (CTS) may be categorised in a number of ways utilising one of a range of presently available grading tools. The grading systems proposed by Bland and Padua are the most commonly used, however, both have limitations, which are discussed in detail in this paper. The aim of this research is to establish, using the best available evidence, a clinically appropriate revision of the current CTS nerve conduction grading tool, and to compare with existing grading tools used in UK Neurophysiology clinics. The revised scale is designed from a clinical physiologist perspective and based on the numerical values of nerve conduction findings. The proposed revised grading system is based on more nuanced, descriptive categories, ranging from Normal to Early, Mild Sensory, Mild Sensory Motor, Moderate Sensory, Moderate Sensory Motor, Severe Sensory Motor, Extremely Severe Sensory Motor, and Complete absence. Method: A total of 1123 patients (2246 hands) were included in this study, with the aim of evaluating the revised grading system. Data was collected based on the extensive and detailed grading systems previously described by Bland and Padua. All data was recorded numerically to ensure methodological reliability. Result: Of the 2246 patients' hands tested, the nerve conduction was graded as normal in 968 hands; nerve conduction showed early changes in 271 hands; mild sensory changes in 215 hands, mild changes in both motor and sensory response in 51 hands; moderate sensory changes in 134 hands; moderate sensory and motor changes in 356 hands; severe changes in motor and sensory responses in 204 hands; extremely severe sensory and motor changes in 33 hands and complete absence of response in 14 hands. Conclusion: The revised grading tool could offer a more numerical grading to the Clinical Physiologist and could help the surgeon to ascertain the level of severity in order to decide on either a conservative or surgical approach to treatment if they decide to use the proposed grading which could support them to defend their decision in cases of litigation.
Keywords: Grading tools for carpal tunnel syndrome; CTS Gradings; Neurophysiological CTS grading
The pathology of Carpal Tunnel Syndrome (CTS) is described as "A Neuropathy caused by entrapment of the median nerve at the level of the carpal tunnel" [[
The Grading tool is used for the diagnostic assessment of CTS in conjunction with the patient's clinical history and symptoms in order to diagnose the degree of severity of CTS [[
There are several primary grading tests mentioned in the different literature, associated with Phalen's, Tinel's and Durkan's signs which are subjective and are based on patient clinical response. Other tests like Ultrasound, NCS and EMG needle examination are objective tests that have been used for CTS grading which are reliable, evidence-based and objective, not dependent on patient clinical response [[
However, to ascertain the severity level of CTS, specific neurophysiological grading is required [[
It appears that whilst there is an accepted dominance of both the Bland [[
In the UK, the Bland [[
The aim of this research was to establish evidence-based revision of the current CTS nerve conduction Grading Tool used in the UK and to evaluate its effectiveness - in terms of acceptability and usability for Clinical Physiologist as well as a tool for intervention prediction for Surgeon. This could support the Surgeon to ascertain the level of severity and decide on a conservative or surgical approach to treatment. Although surgeons must take their own decision for the treatment of CTS, if they want to consider the treatment on the basis of the proposed Nerve conduction study grading, this will probably allow to defend their decisions in the Magistrate Court. A numerical value is given to each of the grade bandings to enable objective reporting and comparision [[
No clinical assessment was conducted during the Neurophysiological test so as to secure the biasness from patient's condition.
Ethical approval for the research project was obtained from the Heath Research Authority National Research Ethics Service London – Queen Square Research Ethics Committee (Reference 17/LO/0750).
Neurophysiological data was collected based on the extensive and complete description of previous study designs by Padua [[
The Association of Neurophysiological Scientists (ANS) (2014) guidelines and the minimum standards for the practice of Clinical Neurophysiology in the United Kingdom were followed. Few new grading was introduced during collection of the data to cover full range of grading.
The test was performed by a qualified Clinical Physiologist (Neurophysiology) using Keypoint 9033A07 (Skovlunde, Denmark) machine, on the bases of departmental protocol (Peripheral protocol1, 2015). A quantitative method was used for collecting data [[
Data was analysed on certain widely accepted assumptions of sensory amplitude and CV and distal motor latency (DML), amplitude and CV [[
The procedure started by carrying out the sensory testing, by placing the stimulating ring electrodes on digit III (which is more sensitive then digit II [[
All patient data was collected by fulfilling the criteria mentioned in above paragraph depending on the severity. The reason for using the new criteria is to describe the full range of severity which was not fully covered by other research mentioned earlier in this paper. Criteria was mentioned in above paragraph are intended to be more reliable in terms of grading for Clinical Physiologist and probably will allow support to the Surgeon in terms of patient treatment decisions.
The grades are:
Normal (Grade 0): where sensory conduction velocity (SCV) is above 50 m/s and amplitude ≥5 μV with DML ≤4.2 ms, amplitude ≥5 mV and motor conduction velocity (MCV) ≥50 m/s.
Early (Grade 1): where SCV is between 45 and 50 m/s from digit III and double peak latency in digit IV is > 0.5 ms with DML ≤4.2 ms and normal sensory and motor amplitude > 5 (sensory in μV and motor in mV).
Mild Sensory (Grade 2): where SCV is between 40 and 44.9 m/s from digits III with normal sensory amplitude and motor values mentioned in Grade 0.
Mild Sensory-Motor (Grade 3): where SCV is between 40 and 44.9 m/s from digits III with normal sensory amplitude mentioned in Grade 0, DML ≥4.2 ms with normal motor amplitude and CV.
Moderate Sensory (Grade 4): where SCV is less than 40 m/s from digits III with normal sensory amplitude and normal motor values mentioned in Grade 0.
Moderate Sensory-Motor (Grade 5): where SCV is less than 40 m/s from digits III with normal sensory amplitude, DML ≥4.2 ms with normal motor amplitude and CV.
Severe Sensory-Motor (Grade 6): where sensory potentials from digits III and digit II are absent or < 3 μV in both digits III and II with SCV < 30 m/s, DML ≥4.2 ms, MCV is either slow or normal.
Extremely Severe Sensory-Motor (Grade 7): where sensory and motor potentials are absent and response recordable only from 2nd lumbricals, where median lumbricals are prolonged compared and low amplitude to ulnar lumbricals.
Complete (Grade 8): where both sensory and motor potentials are absent and responses are not recordable from median 2nd lumbricals but recordable from ulnar 2nd lumbricals. (Please refer to a Comparison of the Bland [[
The data was collected for a period of 1 year (2017). Initially a total of 1132 patients were included in this study. During data collection, two referrals were not included, because the patients declined to participate in all study procedures; and seven participants' data sets were excluded from the analysis because the departmental protocol was breached. Therefore 1123 patients (2246 hands) were included in the final data collection.
Of the 1123 patients, 687 were female and 436 were male. The age range was 19 to 98 years, median age 56 years. The numbers of hands in each grade of severity are shown in Fig. 1 and Table 1.
Graph: Fig. 1 Result
Result
Normal 968 Early 271 Mild sensory 215 Mild S/M 51 Moderate Sensory 134 Moderate S/M 356 Severe S/M 204 Extremely Severe S/M 33 Complete 14 Total Hands 2246
The Bland [[
Bland [[
In theory, the higher the grade, the worse nerve dysfunction
The Table 2 summarises and compares the variance in Bland [[
Percentage comparison with grading of Padua, Bland and Hirani
Padua (%) Bland (%) Hirani (%) Normal = 18 (3) Normal = 3269 (38) Normal =968 (43) Minimal = 123 (21) Very mild = 684 (8) Early =271 (12) Mild = 145 (24) Mild sensory-motor = 944 (11) Mild sensory = 215 (10) Mild S/M = 51 (2) Moderate = 217 (36) Moderately Severe =1359 (16) Moderate sensory = 134 (6) Moderate S/M = 356 (16) Severe = 81 (14) Severe = 568 (7) Severe S/M = 204 (9) Extremely severe = 16 (3) Very severe = 930 (11) Extremely Severe S/M = 33 (1) Extremely Severe = 387 (5) Complete = 14 (1) Total Hands 600 8501 2246
Padua [[
Comparing, the Bland [[
Bland [[
Bland's [[
Bland [[
The Grade 6 in Bland [[
Table 3 summarises and compares the Bland [[
Grading comparison of Bland with propose grading
Grading Bland [ Modified grading by Hirani Grade1 Inching, palm/wrist median/ulnar comparison, ring finger double peak Early: SCV = 45–50 m/s interpeak potentials in digit IV > 0.5 ms, DML < 4.2 ms. Amplitude of sensory ≥5 μV and motor potentials ≥5 mV Grade2 Mild: sensory conduction velocity(SCV) < 40 m/s distal motor latency (DML) < 4.5 ms Mild sensory: SCV = 40–44 m/s with normal sensory amplitude (NSA), DML, motor nerve action potentials (MNAP) and sensory conduction velocity (SCV) & motor conduction velocity (MCV) Grade3 Moderately severe: DML > 4.5 ms and < 6.5 ms with sensory nerve action potentials (SNAP) preserved Mild sensory motor: SCV = 40-44 m/s with NSA, DML > 4.2 ms with normal motor amplitude (NMA) and normal SCV and MCV Grade4 Severe: DML > 4.5 ms and < 6.5 ms with absent SNAP Moderate sensory: SCV < 40 m/s with NSA, normal DML, NMA, SCV and MCV Grade5 Very severe: DML > 6.5 ms. Moderate sensory motor: SCV < 40 m/s with NSA, DML > 4.2 ms, MNA and SCV and MCV Grade6 Extremely Severe: motor nerve action potentials (MNAP) < 0.2 mV, Severe Sensory motor: Absent or < 3 μV SNAP with SCV < 30 m/s with DML > 4.2 ms with either slow or normal MCV and or NMA Grade7 Extremely severe: SNAP and MNAP = absent, but recordable from both median and ulnar 2nd lumbricals with prolonged median 2nd lumbricals response as compare to ulnar lumbricals Grade8 Complete: SNAP and MNAP = absent and absent from median 2nd lumbricals and present from ulnar 2nd lumbricals
The grading system devised by Bland [[
Bland [[
The revised grading tool using a physiological basis offers a more precise numerical grading, which is both objective and repeatable. This could not only help the Clinical Physiologist to grade there result according to the propose grading scale but probably it also support the surgeon to ascertain the level of severity and could help to decide on either a conservative or surgical approach to treatment. Please note that this research was made to amend the grading for Clinical Physiologist. Although surgeons have to take their own decision for the treatment of CTS, but if they want to consider the treatment on the basis of the proposed nerve conduction study grading, this will probably aid defence of their decisions for the court. This is advisable (but not necessary to follow) that Surgeons could consider proposed Grade 1–2 for physiotherapy treatment, Grade 3–4 for conservative or intervention of steroid treatment and Grade 5–7 for surgical intervention where the chances of full recovery. Surgeon could decide for surgical intervention of Grade 8 cases, whether it would be beneficial or not in keeping with the patient's age and other medical history.
Future studies looking at prognosis may be helpful in looking at the outcomes from different interventions for those with different gradings of severity and to look at the implications of motor involvement compared with just sensory fascicle involvement. Collections of data are under process for post surgery CTS outcome which will publish later after approval from BCUHB research committee.
Betsi Cadwaladr University Health Board (BCUHB) funded this study for publication. Awarded Number: 1770146124202136. The role of the funding body is to support financially in publication this research paper. The Author contributed by the collection, analysis and interpretation of data and in writing the manuscript.
The author would like to acknowledge and thank Mrs.Julie Evans, Dr. Gareth Payne, and Dr. Bashir Kassam for their encouragement, guidance and help with this study.
A written consent was obtained from all participants and filed in patient notes and a copy kept in the department.
Salim Hirani carried out the nerve conduction studies, participated in the sequence alignment, drafted the manuscript, design the stufy, performed the statical analysis and carried out the immunoassays. Dr Gareth Payne participated in the sequence alignment. Dr Gareth Payne and Dr Basheer Kassam participated for proof reading. Mrs Julie Evance suported for time allocation in collecting the data analysis. All authors read and approved the final manuscript.
The datasets analyzed during the current study are not publicly available as they are held within patient records but are available from the corresponding author on request.
We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this report is consistent with those guidelines. Ethical approval for the research project was obtained from the Heath Research Authority National Research Ethics Service London – Queen Square Research Ethics Committee (Reference 17/LO/0750).
Not Applicable.
The authors declare that they have no competing interests.
• ANS
- Association of Neurophysiological Scientists
• APB
- Abductor polices braves
• BCUHB
- Betsi Cadwaladr University Health Board
• BSCN
- British Society for Clinical Neurophysiology
• CTS
- Carpal tunnel syndrome
• CV
- Conduction velocity
• DML
- Distal Motor Latency
• GPs
- General Practices
• MCV
- Motor conduction velocity
• MNAP
- Motor nerve action potentials
• NCS
- Nerve Conduction Studies
• NMA
- Normal motor amplitude
• NSA
- Normal sensory amplitude
• SCV
- Sensory conduction velocity
• SNAP
- Sensory nerve action potentials
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By Salim Hirani
Reported by Author