Proposed 10-point CTS scoring system correlates with nerve conduction tests

The system considers four symptoms, four signs and two risk factors for carpal tunnel syndrome and may sometimes replace conduction studies.

Veenesh Selvaratnam

COPENHAGEN, Denmark — British investigators found that a 10-point carpal tunnel syndrome scoring system they developed correlated well with nerve conduction study findings, suggesting that using the scoring system may permit performing the costly — and sometimes painful — nerve conduction tests less often.

“A nerve conduction test is considered to be the diagnostic test of choice,” Veenesh Selvaratnam, MBChB (Liverpool), MRCS (Edinburgh), specialist registrar in trauma and orthopaedics at Mersey Deanery, Liverpool, United Kingdom, said in presenting the results at the 12th EFORT Congress 2011, here.

The new scoring system, which takes into account four carpal tunnel syndrome (CTS) symptoms, four CTS signs, and two risk factors for CTS, effectively indicated which patients were at a higher risk of moderate to severe forms of the syndrome, he said.

Selvaratnam was at Southport and Ormskirk Hospital NHS Trust, United Kingdom, when the study was done.

Prospectively tested

Selvaratnam and colleagues prospectively tested the scoring system developed by senior investigator V. Sahni on 59 patients, including two bilateral cases, for a total of 61 hands. The higher the score, the greater was the likely severity of CTS.

“Our study was done to find a CTS scoring system,” Selvaratnam said.

Patients received a point each for having the four symptoms that investigators included in the scoring system, which were tingling and numbness on the Katz hand diagram (a point given for classic or probable patterns), nocturnal paresthesia and bilateral symptoms, as well as a point each for presenting with any of the four signs that included weak thumb abduction, Tinel sign, Phalen sign and hypoalgesia in the median nerve distribution. Furthermore, patients received a point each for the risk factors of age older than 40 years and female gender, for a possible total score of 10 points.

Some nerve studies avoidable

The investigators correlated the results with the severity of the patients’ condition.

“What our results showed is that all scores of 8 or more matched the nerve conduction study of moderate to severe intensity, apart from three scores which were 8 and above which showed a normal result,” Selvaratnam said.

He provided more details about the three cases with normal conduction study results but with scores of 8 points or more. One patient who scored 8 with a normal nerve conduction study was found to have a cervical disc herniation after a cervical spine MRI. Two other patients with scores of 8 and 9 respectively had a carpal tunnel release even though nerve conduction studies were normal and both reported resolution of symptoms.

“Based on our study, we believe that patients who score less than 8 may require a nerve conduction study to confirm the diagnosis of CTS … however, patients who score 8 and above — they have a 93% chance of having moderate to severe CTS on a nerve conduction study,” Selvaratnam said.

For the study, conducted between May 2009 and May 2010, researchers applied the system preoperatively to every patient prior to any nerve conduction studies being done. Patients included in the study had 17-month symptom duration, mean. The ratio of women to men studied was 2.3 to 1. – by Susan M. Rapp

Reference:

• Selvaratnam V, Shetty V, Manickavasagar T, Sahni V. Carpal tunnel scoring system to predict nerve conduction study results: a prospective study — can we do away with nerve conduction studies? Paper #183. Presented at the 12th EFORT Congress 2011. June 1-4. Copenhagen, Denmark.
• Veenesh Selvaratnam, MBChB (Liverpool), MRCS (Edinburgh), can be reached at Mersey Deanery, Regatta Place, Brunswick Business Park, Summers Road, Liverpool L3 4BL United Kingdom; email: veenesh_selvaratnam@yahoo.co.uk.
• Disclosure: Selvaratnam has no relevant financial disclosures.

Carpal tunnel syndrome (CTS) is extremely common, and carpal tunnel release (CTR) is the most frequent surgery I and most other hand surgeons perform. The role of electrodiagnostic testing is debatable. The test is both uncomfortable and expensive.

Electrodiagnostic testing serves several important roles. First, it establishes a baseline. Patients with severe CTS have permanent nerve damage and are often disappointed that CTR cannot restore feeling to their fingers and motion to their thumb. They may feel that CTR was unsuccessful and request additional surgery. Provided that the preoperative electrodiagnostic testing was done within a few months of surgery, a repeat of the test can establish that the disease has either improved slightly or not progressed and the surgery was successful.

Second, electrodiagnostic testing measures pathophysiology (disease). The symptoms and disability (illness) associated with a given disease vary widely depending on the patient’s circumstances, stress level and coping strategies. It can be argued (and supported by data) that the best arbiter of who will benefit from CTR is electrodiagnostic testing. The argument that even patients with normal or mild electrodiagnostic testing improve with surgery ignores the placebo effect and regression to the mean, and does not hold water. Patients who have surgery for normal electrodiagnostic testing are very likely having unnecessary surgery that can only do them harm.

Brent Grahams’ CTS 6 (a scale based on six common symptoms of CTS) increases the probability of a diagnosis of CTS, but doesn’t match the reference standard. The same is true of this new 10-point system.

I would argue that in the history of medicine, the lack of an objective verification of disease has led to trouble (e.g., whiplash, repetitive strain injury, hysteria). The authors of this study operated on two patients with normal tests. Other surgeons may use the 10-point scale to justify operating on many, many more.

In my opinion, all of these are unwarranted surgeries. The more objective we are in establishing pathophysiology and the better we establish that our treatments are better than placebo, regression to the mean or the self-limited course of the illness, the more likely we are to help rather than harm our patients. This study advances our understanding of the questions about how best to manage CTS, but we don’t have all the answers yet.

— David C. Ring, MD, PhD
Orthopedics Today Editorial Board member
Massachusetts General Hospital
Boston
Disclosure: He has no relevant financial disclosures.

Reference:

• Graham B. The value added by electrodiagnostic testing in the diagnosis of carpal tunnel syndrome. J Bone Joint Surg Am. 2008;90(12):2587-2593.