William J. Hennessey

Sensitivity and specificity of carpal tunnel syndrome signs

The sensitivity and specificity of six carpal tunnel syndrome (CTS) signs were determined by evaluating 143 subjects (228 hands) with symptoms of CTS. Immediately after performing the six physical examination tests, standard nerve conduction studies were performed on all 228 hands to determine the presence or absence of CTS. CTS was present in 142 hands and absent in 86 hands. The signs were not very sensitive (23-69%), but were fairly specific (66-87%) for CTS. A square-shaped wrist and abductor pollicis brevis weakness were the most sensitive signs (69 and 66%, respectively), and are recommended as part of the examination of CTS. Median nerve hypesthesia and the Phalen sign both have fair sensitivity (51%) but good specificity (85 and 76%, respectively). The median nerve compression sign and the Hoffmann-Tinel sign both have poor sensitivity (28 and 23%, respectively), and thus are less helpful in evaluating subjects with suspected CTS.

Standardized nerve conduction studies in the lower limb of the healthy elderly

Nerve conduction studies are commonly performed in elderly individuals. No complete set of reference data for the distal lower limb nerves exists for this population, making it difficult to accurately interpret electrodiagnostic findings. The purpose of this study was to provide reliable reference data by comprehensively examining conduction characteristics in routinely tested peripheral nerves of the lower limb in a healthy elderly population. Conduction studies of the tibial, deep peroneal, sural and medial dorsal cutaneous nerves were performed in one lower limb of 122 healthy elderly individuals between the ages of 60 and 89 years. Peak amplitudes of the sural sensory action potential and the tibial compound muscle action potential correlated significantly with both age and leg length. All other parameters did not show significant correlation with age. Conduction velocities and distal latencies slowed significantly with increasing leg length except for tibial distal latency.

Median and ulnar nerve conduction studies : normative data for young adults

Temperature control and standardized technique, along with consideration of age, height, finger circumference, and instrumentation is imperative for appropriate interpretation of electrodiagnostic studies. Normative data must be based on these factors in adequate numbers of healthy subjects. This study provides comprehensive normative electrodiagnostic data for the median and ulnar nerves. Forty-four subjects participated in this study. The median motor studies showed a motor distal latency (DL) of 3.2 (0.4)msec, and distal amplitude (DAMP) of 12.1 (3.8)mV and sensory studies showed a DL of 2.5 (0.2)msec, and DAMP of 31.4 (8.7) microV for the men and 52.4 (14.3)microV for the women. The ulnar motor studies showed a motor DL of 2.6 (0.3)msec, and DAMP of 12.6 (2.3)mV and sensory studies showed a DL of 2.4 (0.2)msec, and DAMP of 27.0 (7.8)microV for the men and 52.9 (13.9)microV for the women. Sidedness and handedness did not affect the nerve conduction parameters of this study. Aging changes for these nerves were minimal but more apparent for the median nerve. The most noticeable change with aging was the decrease in amplitude of the sensory nerve action potential.

Gender and arm length: Influence on nerve conduction parameters in the upper limb

Abstract Median, ulnar, and radial nerve conduction studies (NCS) were performed in 44 subjects. Students t -test was used to compare nerve conduction velocities (NCV), distal latencies (DL), and distal amplitudes (DAMP) for the two sexes. Only the sensory DAMPs showed statistical significance ( p 2 = .46, p 2 = .59, p 2 = .29, p

Influence of age on nerve conduction

Rivner et al. reported that the “percentage of normals who had no response increased with advancing age” in regard to nerve conduction studies. We find that statement to be largely erroneous. We draw the authors’ attention to our electrodiagnostic studies on the healthy elderly. The healthy elderly subjects were carefully screened. Any medical condition associated with a peripheral neuropathy or the use of any medication associated with a peripheral neuropathy led to the exclusion of the subjects, even if there were no symptoms or signs of a peripheral neuropathy. None of the included subjects resided in a nursing home because of the implication of some degree of chronic illness. A clinical history and physical examination was performed and any subject with symptoms or signs of neuromuscular impairment in any limb was also excluded. We found that sensory responses for the median, ulnar, and radial nerves were readily obtained in all subjects from 60–95 years of age. In the lower limbs, sural responses were obtained in all but two individuals, who were 79 and 85 years of age. A limitation of the study of Dr. Rivner and his colleagues is that the population was not normal. Their normative data were collected on referred patients—not selected healthy subjects—whose data were retrospectively analyzed. In other words, the patients presented seeking an answer to some neurologic symptom that led the referring physician to request an electrodiagnostic consultation. As such, it is strongly implied that some type of pathology was present in these patients. In addition, there may be some discrepancies and difficulties with the techniques applied in obtaining the sensory responses. In some cases, particularly in individuals over 80 years of age, averaging may be needed. We would welcome the opportunity to review more prospective studies on healthy elderly subjects. Based upon our experience, the absence of recordable sensory nerve action potentials in the upper limbs should clearly be considered abnormal, and the absence of recordable sensory nerve action potentials in the lower limbs of a symptomatic elderly subject is highly suspicious for the presence of significant pathology.

GENDER AND ARM LENGTH: INFLUENCE ON NERVE CONDUCTION PARAMETERS IN THE UPPER LIMB

Median, ulnar, and radial nerve conduction studies (NCS) were performed in 44 subjects. Students t-test was used to compare nerve conduction velocities (NCV), distal latencies (DL), and distal amplitudes (DAMP) for the two sexes. Only the sensory DAMPs showed statistical significance (p < .001) for gender. Women had greater mean median (52.4 microV vs 31.4 microV), ulnar (52.9 microV vs 27.0 microV), and radial (46.1 microV vs 20.1 microV) sensory DAMPs. Stepwise linear regression analysis of NCVs, DLs, and DAMPs on gender and arm length showed statistical significance only for the median (R2 = .46, p < .001), ulnar (R2 = .59, p < .001), and radial sensory DAMPs (R2 = .29, p < .001) for gender. Arm length did not account for any additional variability. Gender showed an effect on the distal sensory DAMPs obtained by antidromic technique in this study. In contrast to the reported effect of leg length and height on lower limb studies, arm length did not affect upper limb studies.