Diagnostic yield of different electrophysiological methods in carpal tunnel syndrome

Comparison of sensory conduction techniques in the diagnosis of mild idiopathic carpal tunnel syndrome: which finger, which test?

To compare the sensitivity of different electrodiagnostic tests on the same hand affected by mild carpal tunnel syndrome (CTS), 189 hands with the clinical diagnosis of CTS and 61 hands of healthy persons were evaluated prospectively. On all hands, median sensory studies from digits 1, 2, 3, 4, and the palm-to-wrist segment from digit 3 and medial motor latency were recorded. Sixty-two hands with delayed motor latency (>4.2 ms) were excluded to ensure that only mild cases were enrolled. Sensory median-radial latency differences from the thumb, median-ulnar latency difference between second and fifth digits, and median-ulnar latency difference from the fourth digit were calculated in each limb. Sensory studies of only one median innervated digit failed to diagnose 15-20% of hands. Conduction velocity at the palm-to-wrist segment was the most sensitive, diagnosing 99% of cases. In comparative tests, median radial sensory latency difference from the first digit was the most sensitive (94%), and median ulnar latency difference from the fourth digit was the least (85%) sensitive. Segmental measurement has the highest diagnostic yield and may be used first in the evaluation of CTS.

Correlation of clinical history and electrodiagnostic abnormalities with outcome after surgery for carpal tunnel syndrome

A retrospective study on 294 wrists in 154 patients who had been diagnosed with carpal tunnel syndrome and subsequently had surgery performed was undertaken; both clinical and electrodiagnostic findings were correlated. The cases were divided into three groups based on electromyographic severity (mild, moderate, severe), and recovery from symptoms was evaluated after 1 week, 3 months, and 1 year. The cases were also divided into five groups based on symptom duration, and the same investigations were performed. All operations were conducted by applying the open release method with the limited-palmar incision technique. Operative outcomes showed no association between recovery from symptoms and the severity of electromyographic findings or the duration of symptoms, although the group that had the shortest duration of symptoms recovered faster than the long-duration groups statistically. Postoperative results after 1 year were also successful for those patients who had had symptoms of long duration. Of the 294 wrist operations studied, good to excellent postoperative outcomes were recorded in 242 cases (82 percent), fair outcomes in 39 cases (13 percent), and poor outcomes in 13 cases (4 percent). Patients whose electromyogram revealed double crush syndrome still showed improvement, with good-to-excellent results in 11 out of 15 cases (73 percent). Patients with diabetes mellitus also showed improvement, with good-to-excellent results in 14 out of 19 patients (74 percent). This study showed that postoperative results were satisfactory within 1 year, regardless of the degree of electromyographic severity, symptom duration, presence of diabetes mellitus, or double crush syndrome.

Neurophysiological classification of carpal tunnel syndrome: assessment of 600 symptomatic hands

Following the AAEM electrodiagnostic guidelines, we developed a neurophysiological classification of carpal tunnel syndrome (CTS). Six hundred hands with clinical CTS (mean age 51.4 yr., female/male ratio 5.5/1, right/left ratio 1.8/1) were prospectively evaluated and divided into six classes of severity only on the basis of median nerve electrodiagnostic findings: extreme CTS (EXT-absence of thenar motor responses), severe CTS (SEV-absence of sensory response and abnormal distal motor latency-DML), moderate CTS (MOD-abnormal digit-wrist conduction and abnormal DML), mild CTS (MILD-abnormal digit wrist conduction and normal DML), minimal CTS (MIN-exclusive abnormal segmental and/or comparative study), and negative CTS (NEG-normal findings at all tests). Using this neurophysiological classification, the CTS groups appeared normally distributed (EXT 3% of cases, SEV 14%, MOD 36%, MILD 24%, MIN 21%, NEG 3%), and the age of patients and clinical findings appeared to be related to neurophysiological abnormalities. Significant differences in median neurophysiological parameters not included in the classification (such as palm-wrist sensory conduction velocity) were observed in the different CTS groups. The analysis of the groups showed that: 1) the majority of advanced cases (SEV and EXT) occurred in older patients (60-80 years), 2) most of the milder cases (MIN and MILD) occurred in young female patients. The aim of this study was to standardise the neurophysiological evaluation of CTS.

A useful electrophysiologic parameter for diagnosis of carpal tunnel syndrome

In 43 patients (50 hands) with clinical manifestations of mild-moderate carpal tunnel syndrome (CTS) and 36 healthy volunteers (40 hands), orthodromic sensory nerve conduction velocity (SNCV) was measured with surface electrodes in the median nerve between the third digit and palm and between the palm and wrist. These figures were used to calculate the ratio of distal to proximal conduction (distoproximal ratio). All 90 hands were also subjected to other nerve conduction studies used for diagnosis of CTS. All control hands presented distoproximal ratios < 1.0 reflecting higher conduction rates in the proximal segment. In contrast, 49 of 50 CTS hands (98%) presented reversed ratios (> 1.0) indicating compromised proximal conduction. The sensitivity of this test was significantly greater than that of other methods evaluated, including comparative studies and segmental study of the palm-wrist portion of the median nerve. Segmental study of median SNCV with calculation of the distoproximal ratio is a sensitive technique for diagnosis of CTS in patients with normal findings in standard nerve conduction studies.

Carpal tunnel syndrome and gynaecomastia during growth hormone treatment of elderly men with low circulating IGF-I concentrations

OBJECTIVE

We studied the relationship between plasma level of insulin-like growth hormone I (IGF-I), changes in lean body mass and in adipose mass, and adverse side-effects during human growth hormone (hGH) treatment of elderly men who had low IGF-I levels.

DESIGN

The first six months was a period of baseline observation. The subjects were then randomized into two groups so that during months 7-18, men in group I received hGH, and men in group II served as untreated controls.

SUBJECTS

Eighty-three overtly healthy elderly men, who were selected because their plasma IGF-I level was less than 0.35 units/ml. The men were randomly assigned in a ratio of three to one into group I (n = 62) or into group II (n = 21).

MEASUREMENTS

Plasma IGF-I level was measured monthly. Lean body mass and adipose mass were measured every six months.

RESULTS

Fifteen men left the study during the baseline period because of personal reasons or intercurrent medical events. In those who received drug (group I), there were a number of adverse reactions which could have been related to the hGH therapy: carpal tunnel syndrome 10, gynaecomastia 4, and hyperglycaemia 3. In total there were 27 dropouts from group I and two dropouts from group II after the six-month point, for a variety of medical and non-medical reasons, the majority probably not related to hGH therapy. During the hGH treatment of group I, plasma IGF-I increased from the range 0.10-0.35 units/ml into the range 0.5-2.2 units/ml. Among the 18 men who completed 12 months of hGH treatment without experiencing one of the three above-noted presumed hGH side-effects, mean and peak plasma IGF-I during treatment were significantly lower than among the 13 men who experienced carpal tunnel syndrome or gynaecomastia (one subject had both) while on hGH. With one exception, neither carpal tunnel syndrome nor gynaecomastia occurred in any individual with a mean IGF-I level less than 1.0 units/ml during hGH treatment. Twelve months of hGH treatment (group I) caused an increase in lean body mass to 106% of the initial baseline (month one of the protocol), and a reduction in adipose mass to 84% of the baseline. Meanwhile, the lean body mass of the untreated men in group II declined to 97% of the initial baseline. The body composition responses after 12 months of treatment in group I were larger in the men whose mean intra-treatment IGF-I level was 0.5-1.0 units/ml, than in the men whose mean intra-treatment IGF-I level was 1.0-1.5 units/ml.

CONCLUSIONS

These observations show that when elderly men with low circulating IGF-I concentrations are treated continuously with hGH, elevation of plasma IGF-I above 1.0 units/ml is associated with a substantial frequency of carpal tunnel syndrome or gynaecomastia. It may be that the effects of the hormone in expanding lean body mass and reducing adipose mass can be achieved, and the side-effects avoided, by maintaining the mean IGF-I level in the range 0.5-1.0 units/ml.

Lumbrical and interossei recording in carpal tunnel syndrome

Median motor studies are commonly "normal" in mild carpal tunnel syndrome (CTS). This reflects either the sparing of motor compared to sensory fibers, or the inability of conventional studies to detect an abnormality. A novel approach to demonstrate early motor fiber involvement in CTS is the placement of the same active electrode lateral to the third metacarpal, allowing recording from the second lumbrical or the deeper interossei, when stimulating the median or ulnar nerves at the wrist, respectively. We compared the difference between these latencies in 51 normal control hands to 107 consecutive patient hands referred with symptoms and signs suggestive of CTS, who were subsequently proven to have electrophysiologic CTS by standard nerve conduction criteria. A prolonged lumbrical-interossei latency difference (> 0.4 ms) was found to be a sensitive indicator of CTS in all patient groups. It was also helpful in patients with coexistent polyneuropathy, where localization at the wrist was otherwise difficult.