An algorithm for the safety of costal diaphragm electromyography derived from ultrasound.

INTRODUCTION: Costal diaphragm electromyography (EMG) remains unpopular due to the risk of pneumothorax. In this study we assessed the safety of the "trans-intercostal" method of diaphragm EMG using B-mode ultrasound. METHODS: Twenty healthy subjects participated in this investigation. The diaphragm and the lung were visualized in the most distal intercostal space (dICS) with ultrasound. The risk of pneumothorax was assessed at the mid-clavicular, anterior, and mid-axillary levels, during normal and deep breathing, in supine and upright postures. RESULTS: The dICS at the anterior axillary level was the safest landmark for diaphragm EMG during normal breathing, with the subject supine. The mid-clavicular level is the least optimal location for EMG. The upright position and deep breaths increase the risk of pneumothorax. CONCLUSIONS: The safety of the trans-intercostal method of diaphragm EMG depends on the anatomic level chosen to insert the needle, patient position, and breathing pattern. Hence, we have developed a safety algorithm for electromyographers.

Is there a case for diaphragm pacing for amyotrophic lateral sclerosis patients?

Respiratory pacing has advanced the long-term management of respiratory failure secondary to neurological disorders. It has an established role in curtailing invasive mechanical ventilation after upper motor neuron lesions such as spinal cord injury. There is increasing interest to expand the application of intramuscular diaphragm pacing to amyotrophic lateral sclerosis (ALS), a progressive and fatal neurodegenerative disease. Although diaphragm pacing has been offered to ALS patients, evidence-based data to determine its benefits remain lacking. The limited current literature indicates progression of respiratory dysfunction in ALS patients despite diaphragm pacing. The data from clinical trials are inadequate to substantiate its survival and sleep benefits. Its advantages over non-invasive mechanical ventilation have not been directly investigated. Furthermore, there are cautions for ALS patients to consider when opting for diaphragm pacing. Progressive degeneration of the phrenic motor neurons in classic ALS will interrupt the transmission of pacer signals to sustain diaphragm contractions. Pacing protocols that are safe for other neurological conditions may be detrimental for ALS, at least as suggested by transgenic animal models. Issues inherent to the device warrant expert intervention in implanted patients. At present, clinical effectiveness and long-term safety concerns about diaphragm pacing in ALS remain to be addressed.

Validity and reliability of the Purdue Pegboard Test in carpal tunnel syndrome.

There is a paucity of validated tests to quantify hand function impairment due to carpal tunnel syndrome (CTS). The aim of this study was to test the validity and reliability of the Purdue Pegboard Test (PPT) in CTS patients. We compared 190 CTS patients with 122 healthy, age-matched controls. CTS severity was determined based on electrophysiologic parameters and the Levine Self-Assessment Questionnaire. The time to complete the PPT and the test-retest reliability were tested. The test-retest reliability was high with an intraclass correlation coefficient of 0.91. Compared to healthy controls, the CTS patients were significantly slower. Although the functional performance generally declined with increasing severity of electrophysiologic abnormalities, the correlation between hand function decline and symptom severity in the young and middle-aged groups was low. We conclude that the PPT is a valid and reliable tool to quantify functional impairment caused by CTS. It can be a useful outcome measure in young and middle-aged patients.

Discriminative validity and test-retest reliability of the Dellon-modified Moberg pick-up test in carpal tunnel syndrome patients.

There is a scarcity of validated hand performance tests with proven reliability for quantifying functional deficits in patients with carpal tunnel syndrome (CTS). The Dellon-modified Moberg pick-up test (DMMPUT), composed of commonly used daily objects, is potentially well suited for that purpose. This study was designed to evaluate the test-retest reliability and discriminative validity of the DMMPUT in CTS patients. We compared 162 CTS patients with 116 age-matched controls. CTS severity was determined based on electrophysiological parameters and Levine's Self-Assessment Questionnaire. The mean time to complete each subset of the DMMPUT by the CTS patients was compared with that by the healthy subjects. Test-retest reliability was examined in 46 CTS patients. Discriminative validity was demonstrated through a significant difference in test completion time between the CTS subjects and their age-matched controls. With few exceptions, the test scores declined with increasing severity of electrophysiological abnormalities and subjective symptom severity. Test-retest reliability of the DMMPUT was high with an intra-class correlation coefficient of 0.91. The DMMPUT has discriminative validity and high test-retest reliability in patients with CTS. It can be a useful standardized outcome measure to gauge disease severity.

The impact of ulnar nerve compression at the elbow on the hand function of heavy manual workers.

The objectives of this article were to study the impact of the hand function disability due to ulnar neuropathy at the elbow (UNE) on workers engaged in occupations requiring heavy hand use. Four patients (42.5 +/- 7 years old), all engaged in heavy-duty jobs, with severe conduction block but without severe axonal loss were recruited. The severity of ulnar nerve compression was quantified based on electrophysiologic studies, Jebsen-Taylor Hand Function Test, Jamar dynamometer, and Semmes-Weinstein Monofilaments Test. UNE resulted in a reduction in hand strength without any significant impact on fine motor dexterity. The 4 laborers whose work required strong hand grip found this debilitating. Severe UNE affects the hand function of heavy manual workers by impeding their grip and pinch strengths. However, UNE does not affect tasks requiring fine hand dexterity.

Compression of the ulnar nerve at the elbow by an intraneural ganglion.

A rare cause of ulnar nerve compression at the elbow is presented in this report. A 42 year old right-handed mechanic developed subacute, progressive numbness, tingling and weakness in his right hand. Electrophysiologic studies demonstrated a severe conduction block affecting the ulnar nerve in the retrotrochlear groove but without any sign of major axonal loss. His hand functions were carefully studied prior to surgery. While fine motor tasks were not affected, the hand strength was markedly diminished. At surgery, a 1-cm diameter intraneural ganglion at the site of the conduction block was found and excised. The patient made a dramatic recovery within 6 weeks post-surgery. The conduction block completely resolved and the hand functions also returned to normal. This and other reported cases point to the importance of early diagnosis and intervention.

Brief post-surgical electrical stimulation accelerates axon regeneration and muscle reinnervation without affecting the functional measures in carpal tunnel syndrome patients.

Electrical stimulation (ES) of injured peripheral nerves accelerates axonal regeneration in laboratory animals. However, clinical applicability of this intervention has never been investigated in human subjects. The aim of this pilot study was to determine the effect of ES on axonal regeneration after surgery in patients with median nerve compression in the carpal tunnel causing marked motor axonal loss. A randomized control trial was conducted to provide proof of principle for ES-induced acceleration of axon regeneration in human patients. Carpel tunnel release surgery (CTRS) was performed and in the stimulation group of patients, stainless steel electrode wires placed alongside the median nerve proximal to the surgical decompression site for immediate 1 h 20 Hz bipolar ES. Subjects were followed for a year at regular intervals. Axonal regeneration was quantified using motor unit number estimation (MUNE) and sensory and motor nerve conduction studies. Purdue Pegboard Test, Semmes Weinstein Monofilaments, and Levine's Self-Assessment Questionnaire were used to assess functional recovery. The stimulation group had significant axonal regeneration 6-8 months after the CTRS when the MUNE increased to 290+/-140 (mean+/-SD) motor units (MU) from 150+/-62 MU at baseline (p<0.05). In comparison, MUNE did not significantly improve in the control group (p>0.2). Terminal motor latency significantly accelerated in the stimulation group but not the control group (p>0.1). Sensory nerve conduction values significantly improved in the stimulation group earlier than the controls. Other outcome measures showed a significant improvement in both patient groups. We conclude that brief low frequency ES accelerates axonal regeneration and target reinnervation in humans.

Accelerating axon growth to overcome limitations in functional recovery after peripheral nerve injury.

OBJECTIVE: Injured peripheral nerves regenerate at very slow rates. Therefore, proximal injury sites such as the brachial plexus still present major challenges, and the outcomes of conventional treatments remain poor. This is in part attributable to a progressive decline in the Schwann cells' ability to provide a supportive milieu for the growth cone to extend and to find the appropriate target. These challenges are compounded by the often considerable delay of regeneration across the site of nerve laceration. Recently, low-frequency electrical stimulation (as brief as an hour) has shown promise, as it significantly accelerated regeneration in animal models through speeding of axon growth across the injury site. METHODS: To test whether this might be a useful clinical tool, we carried out a randomized controlled trial in patients who had experienced substantial axonal loss in the median nerve owing to severe compression in the carpal tunnel. To further elucidate the potential mechanisms, we applied rolipram, a cyclic adenosine monophosphate agonist, to rats after axotomy of the femoral nerve. RESULTS: We demonstrated that effects similar to those observed in animal studies could also be attained in humans. The mechanisms of action of electrical stimulation likely operate through up-regulation of neurotrophic factors and cyclic adenosine monophosphate. Indeed, the application of rolipram significantly accelerated nerve regeneration. CONCLUSION: With new mechanistic insights into the influencing factors of peripheral nerve regeneration, the novel treatments described above could form part of an armament of synergistic therapies that could make a meaningful difference to patients with peripheral nerve injuries.

Corticosteroid iontophoresis to treat carpal tunnel syndrome: a double-blind randomized controlled trial.

Even though injection of corticosteroids into the carpal tunnel alleviates the symptoms of mild to moderately severe carpal tunnel syndrome (CTS), it has not gained universal popularity due to its invasiveness. This study was designed to investigate the effectiveness of dexamethasone iontophoresis as a noninvasive method of treating CTS. We carried out a double-blind randomized controlled trial comparing six sessions of iontophoresis with 0.4% dexamethasone sodium phosphate with distilled water in 17 patients. Outcome measures including nerve conduction studies, the Levine Self-Assessment Questionnaire, and the Semmes-Weinstein Monofilaments were done monthly for 6 months after intervention. Most of the outcome measures did not show any significant change following treatment. Although there was subjective improvement of symptom severity scores in the treatment group as quantified by the Levine Self-Assessment Questionnaire, similar improvement was also observed in the control group (P < 0.05). Although corticosteroid iontophoresis is feasible in clinical settings and is well-tolerated by patients, iontophoresis of 0.4% dexamethasone was not effective in the treatment of mild to moderate CTS. Muscle Nerve 39: 627-633, 2009.

Normative values and the effects of age, gender, and handedness on the Moberg Pick-Up Test.

The Moberg Pick-Up Test is a standardized test for assessing hand dexterity. Although reduction of sensation in the hand occurs with aging, the effect of age on a subject's performance of the Moberg Pick-Up Test has not been examined. The primary goal of this study was to examine the impact of aging and, secondarily, the impact of gender and handedness, on performance of the Moberg Pick-Up Test in 116 healthy subjects. The average time to complete each of the four subsets of the test was analyzed using the Kruskal-Wallis, Mann-Whitney U, and Wilcoxon signed-rank tests. The results show that hand dexterity of the subjects was significantly affected by age, with young subjects being the fastest and elderly subjects the slowest. Women accomplished the test faster than men, and task performance with the dominant hand was faster than with the non-dominant hand. Use of normative values established based on age and gender is a valuable objective tool to gauge hand function in patients with different neurologic disorders.

Randomized controlled trial of strength training in post-polio patients.

Many post-polio patients develop new muscle weakness decades after the initial illness. However, its mechanism and treatment are controversial. The purpose of this study was to test the hypotheses that: (1) after strength training, post-polio patients show strength improvement comparable to that seen in the healthy elderly; (2) such training does not have a deleterious effect on motor unit (MU) survival; and (3) part of the strength improvement is due to an increase in voluntary motor drive. After baseline measures including maximum voluntary contraction force, voluntary activation index, motor unit number estimate, and the tetanic tension of the thumb muscles had been determined, 10 post-polio patients with hand involvement were randomized to either the training or control group. The progressive resistance training program consisted of three sets of eight isometric contractions, three times weekly for 12 weeks. Seven healthy elderly were also randomized and trained in a similar manner. Changes in the baseline parameters were monitored once every 4 weeks throughout the training period. The trained post-polio patients showed a significant improvement in their strength (P < 0.05). The magnitude of gain was greater than that seen in the healthy elderly (mean +/- SE, 41 +/- 16% vs. 29 +/- 8%). The training did not adversely affect MU survival and the improvement was largely attributable to an increase in voluntary motor drive. We therefore conclude that moderate intensity strength training is safe and effective in post-polio patients.

Double-blind randomized controlled trial of low-level laser therapy in carpal tunnel syndrome.

Several studies have suggested that low-level laser therapy (LLLT) is effective in patients with carpal tunnel syndrome (CTS). In a double-blind randomized controlled trial of LLLT, 15 CTS patients, 34 to 67 years of age, were randomly assigned to either the control group (n = 8) or treatment group (n =7). Both groups were treated three times per week for 5 weeks. Those in the treatment group received 860 nm galium/aluminum/arsenide laser at a dosage of 6 J/cm2 over the carpal tunnel, whereas those in the control group were treated with sham laser. The primary outcome measure was the Levine Carpal Tunnel Syndrome Questionnaire, and the secondary outcome measures were electrophysiological data and the Purdue pegboard test. All patients completed the study without adverse effects. There was a significant symptomatic improvement in both the control (P = 0.034) and treatment (P =0.043) groups. However, there was no significant difference in any of the outcome measures between the two groups. Thus, LLLT is no more effective in the reduction of symptoms of CTS than is sham treatment.