Proximal Motor Nerve Research Articles

Targeted Muscle Reinnervation in Amputees: A Review of Current Techniques

Targeted muscle reinnervation (TMR) is a surgical technique that was initially developed for amputees to improve prosthetic control. TMR reroutes the ends of amputated nerves into more proximal motor nerves supplying residual redundant muscle groups. In doing so, it restores motor signals from the brain that would otherwise be lost by the amputation and allows the redundant muscle to communicate this lost function to a prosthetic device. Although initially developed for functional purposes, TMR has subsequently been shown to treat neuropathic and phantom limb pain. As such, indications for its use have significantly expanded. TMR is now widely performed for both upper and lower extremity amputees, at various amputee levels. While technical roadmaps have been published for many amputation levels, the goal of this paper is to update and summarize all these techniques in one place.

Optimal reference electrode placement for accessory and axillary nerve conduction studies

Various techniques are described for proximal motor nerve conduction studies (NCSs). We investigated alternative reference electrode (E2) locations for accessory and axillary NCSs. Multi-channel recordings were made from trapezius or deltoid referred to different sites, and from those sites referred to a remote electrode. Responses were compared using grouped statistics, and correlation analysis. For accessory NCSs, all belly:E2 montages showed comparable responses but axillary NCSs were more variable. Low amplitude contamination was seen at the sternum and contralateral acromion but greater distortion using other potential E2 sites. In both accessory and axillary studies, the ipsilateral acromion showed moderate activity, which correlated with the belly:remote response. Variation in E2 electrode sites may significantly distort the measured compound muscle action potential (CMAP). For accessory and axillary NCS, a sternal reference has favorable characteristics. Other sites, such as ipsilateral acromion or deltoid insertion, may not yield a representative CMAP.

Hyperglycemia and diabetes mellitus are related to vestibular organs dysfunction: truth or suggestion? A literature review.

Diabetes mellitus is an independent risk factor for falling, particularly in the elderly. Due to chronic hyperglycemia and hyperinsulinemia patients with diabetes mellitus may have neurological deficits as peripheral neuropathy that is a debilitating micro-vascular complication affecting the proximal and distal peripheral sensory and motor nerves. Sensory neuropathy is prominent and represents the chief contributor to postural instability in diabetic subjects. Diabetic retinopathy is another complication consequent to a breakdown of the inner blood-retinal barrier with accumulation of extracellular fluids in the macula and growth of new vessels causing retinal detachment. Together peripheral neuropathy and retinopathy contribute to increase the risk of falls in diabetic patients, but a certain vestibular organs impairment should not be underestimated. Nevertheless, the exact mechanism and localization of peripheral vestibular damage consequent to chronic hyperglycemia and hyperinsulinemia are currently not still understood. Moreover it is not defined the possible role of these two blood conditions in worsening the prognosis of typical vestibular pathologies like "benign paroxysmal positional vertigo" and "Meniere disease". The aim of this review was to retrieve all studies investigating about the balance system alterations in patients suffering of diabetes. A search thorough Ovid MEDLINE was performed to enroll all eligible articles. Fourteen studies comprising a total of 1364 patients were included and analyzed in detail. On the basis of data reported in our review it appears plausible to hypothesize a direct connection among chronic hyperglycemic/hyperinsulinemic damage and peripheral vestibular organ dysfunction.

Evaluation of proximal and distal motor nerve conduction using the electrical root stimulation technique in the femoral and obturator nerves.

This study aimed to investigate the adaptability of the electrical root stimulation technique by achieving normative data from the obturator and femoral nerves of healthy dogs. For this purpose, two stimulations and recordings were performed on both the obturator and femoral nerves in 40 dogs (22 males and 18 females). Electrical root stimulation was applied via monopolar needle electrodes between the sixth to seventh and fifth to sixth lumbar interarcuate spaces to the obturator and femoral nerves, respectively. Muscle waves were recorded from the gracilis and sartorius muscles of the left and right pelvic limb. The proximal motor nerve conduction velocity was 60.89 ± 3.93 m/s and 59.87 ± 4.83 m/s in the obturator and femoral nerves, respectively. Our results showed that electrical root stimulation could be a useful method to test the integrity of the roots of obturator and femoral nerves and their proximal parts.

ID 79 – The usefulness of miotatic electronic reflex (T-reflex) in early stages of Guillain Barre syndrome. A case report

Objective Guillain-Barre Syndrome (GBS) diagnosis in its early stages remains a clinical challenge and thus new diagnostic techniques need to be incorporated. The aim of this work is to evaluate the usefulness of miotatic electronic reflex (T-reflex) in initial phases of GBS. Methods A 46-year-old woman was admitted with 7 days of distal paresthesias and intense interscapular pain. Serial electrodiagnostic studies (EDX) on 7th & 33rd day following clinical onset included motor and sensory nerve conduction, somatosensory evoked potentials (SEP) and T-reflex. Results First study showed minimal abnormalities in proximal motor nerve conduction (appearance of A waves and inconsistent F waves) and abolition of Achilles T-reflex bilaterally. Central and peripheral sensory nerve studies were normal. Second study (3 weeks after immunoglobulin treatment) showed disappearance of abnormalities detected in proximal motor nerve conduction and “ad integrum” recovery of Achilles T-reflex. Conclusions T-reflex provides a complete study of the miotatic reflex including 1A sensory fibers unexplored by conventional EDX. Therefore, this test can contribute to GBS diagnosis in its early stages and, as in this case, suggests the presence of dorsal roots conduction block. Thus, it would be desirable to incorporate T-reflex in GBS studies.

Usefulness of cervical root magnetic stimulation in assessing proximal motor nerve conduction

Objectives: To evaluate the reliability and utility of cervical root magnetic stimulation in exploring proximal motor conduction. Methods: In 20 patients with demyelinating polyneuropathy (DPN), 20 patients with amyotrophic lateral sclerosis (ALS) and 25 healthy subjects, evoked compound muscle action potentials (CMAPs) were recorded from abductor digiti minimi muscle in response to electrical stimulation up to Erb’s point and magnetic stimulation up to the cervical roots. Results: In all healthy and ALS subjects, magnetic root stimulation confirmed the absence of conduction abnormalities, including those in whom supramaximal responses at Erb’s point were not achieved. In the DPN group, conduction block and/or temporal dispersion was revealed by magnetic root stimulation in 9 out of 20 patients (45%), 3 more than those detected at Erb’s point. Conclusions: Cervical root stimulation allowed clear distinction between motor neuronopathy and DPN. It is recommended as part of the routine evaluation of patients suspected of having DPN, especially when distal nerve studies are inconclusive.

Diagnosis value of abnormal distribution of electrophysiological parameters in Guillaln-Barre syndrome

Objective To investigate diagnosis value of abnormal distribution of electrophysiological parameters in Guillain-Barre syndrome. Methods 40 cases of Guillain-Barre syndrome were chosen as an object of study, all patients electrophysiological examination. Record limbs on both sides, upper and lower extremities and proximal and distal motor nerve distal latency （ DML）, motor conduction velocity （ MCV ）, compound muscle action potential （CMAP） and sensory conduction velocity（SCV） were recorded. Results F wave latency mildly abnormal, moderately abnormal and severe abnormalities were 18.3 % ,6.2 % and 5.3 %, totaling 29.8 %, F-wave occurrence rate mildly abnormal,moderately abnormal and severe abnormalities were 9.3 % 9.8% and 15.6% ,totaling 66.9%. Abnormal sensory conduction velocity was 57.5% ,motor conduction velocity anomaly was 75.7%, there was a statistically significant difference between the two groups （x^2 = 5.34, P 〈 0. 05 ）. bilateral tibial nerve tests showed mild, moderate and severe in patients with H-reflex abnormality rates were 78.0% ,80.9% and 100.0% ,among the three comparison （ Uc = 1.47 ,P 〉 0.05 ）. 3 proximal and distal motor nerve severe damage rates were 48.3 percent and 74.5 percent, the difference was statistically Significant （ x^2= 9.86, P 〈 0. 05 ）. Severe upper limb proximal nerve damage was 51.4%, significantly lower than 71.6% of the distal upper extremity, lower extremity proximal nerve severe damage to 44.2 % , significantly lower than the 81.6% of distal lower extremity between them were statistical difference （x^2 = 8.86,12.43, all P 〈 0.05 ）. Conclusion Electrophysiological parameters detection Guillain-Barre syndrome has a high value, which can be accurate response in patients with neurological damage. Key words: Guillain-Barre syndrome ; Nerve conduction; Physiology; Nerve

Electrical stimulation of lumbar spinal nerve roots in dogs.

The aim of this study was to test the applicability of electrical stimulation of lumbar spinal nerve roots and obtain normative electrical root stimulation (ERS) data for L7 nerve root and sciatic nerve in dogs. For that purpose ERS and sciatic nerve stimulations were performed consecutively, in totally 40 healthy dogs. ERS was applied in the L7/S1 intervertebral space via monopolar needle electrodes. Muscle responses were recorded from the gastrocnemius muscles on the left and right hind limbs. Sciatic nerve stimulation was performed at the greater trochanter level on the left hind limb, with records obtained from the left gastrocnemius muscle. Mean root latencies of the left and right side were 5.22 ± 0.49 ms and 5.29 ± 0.53 ms, respectively. There was no significant difference in root latency between the right and left sides. The mean terminal latency was 3.82 ± 0.46 ms. The proximal motor nerve conduction velocity of the sciatic nerve was 63.15 ± 3.43 m/s. The results of this study show that ERS provides objective data about the integrity of lumbar spinal nerve roots by evaluating the entire population of motor fibres and total length of the motor axon in dogs. ERS can be considered a useful diagnostic method for confirmation of diagnoses of lumbosacral diseases.

80. Neurophysiological evaluation of the ulnar nerve at the elbow

In clinical practice there are many neurophysiological evaluations of mononeuropathies of ulnar nerve at the elbow. Our aim was to determine the most highly sensitive nerve conduction studies for the ulnar nerve entrapment at the elbow. We evaluate ulnar and median nerve in 10 healthy subjects; we study latency, amplitude and conduction velocity of compound nerve action potential (CNAP) at 10 cm proximal medial epicondyle and motor nerve conduction velocity (mNCV) across the elbow recorded from adductor digiti minimi (ADM), first dorsal interosseous (FDI) and flexor carpi ulnaris (FCU) before and after anodal DC stimulation (2 mA, 20 min) at the elbow. Anodal nerve stimulation reduces ulnar CNAP amplitude by 27% (p = 0.0102) and mNCV recorded from FCU by 11% (p = 0.049) without any changes in median CNAP and ulnar mNCV recorded from ADM and FDI. Anodal DC stimulation induces a partial conduction block at the elbow; our findings suggest that evaluation of ulnar CNAP amplitude and mNCV recorded from FCU are the most sensitive electrophysiological variable to identify ulnar block at the elbow.

9. Diagnostic and prognostic usefulness of proximal radial motor nerve conduction study in acute compressive radial neuropathy

9. Diagnostic and prognostic usefulness of proximal radial motor nerve conduction study in acute compressive radial neuropathy

Diagnostic and Prognostic Usefulness of Proximal Radial Motor Nerve Conduction Study in Acute Compressive Radial Neuropathy

Diagnostic and Prognostic Usefulness of Proximal Radial Motor Nerve Conduction Study in Acute Compressive Radial Neuropathy

Nerve Transfer for Elbow Flexion in Radiation-Induced Brachial Plexopathy: A Case Report

Radiation-induced brachial plexopathy is an uncommon but devastating late complication seen in patients receiving radiation therapy to the chest wall and axilla. Treatment options are unfortunately limited. We report a case of a 59-year-old woman treated with radiation therapy for breast cancer 12 years earlier, who presented with loss of elbow flexion and marked shoulder weakness. Electromyogram and intraoperative stimulation of the musculocutaneous nerve branches were consistent with a proximal motor nerve conduction block. Microsurgical transfer of median and ulnar nerve fascicles to the biceps and brachialis branches of the musculocutaneous nerve, respectively, were performed. The patient recovered MRC grade 4/5 elbow flexion after surgery. The characteristics of this disorder and surgical treatment options are reviewed.

Acute polyradiculoneuropathy with renal failure: mind the anion gap

We describe a 47-year-old male who presented with acute renal failure and later developed bilateral facial weakness, complete ophthalmoplegia, flaccid tetraparesis and diminished sensation in the extremities. Renal biopsy and...

Functional Reinnervation of the Canine Bladder after Spinal Root Transection and Immediate End-on-End Repair

The goal of this study was to transect and immediately repair ventral roots, selected by their ability to stimulate bladder contraction, to assess the feasibility of bladder reinnervation in a canine model. Brain-derived neurotrophic factor (BDNF) was delivered via an osmotic pump (0.5 or 5 mg/mL) to a cuff surrounding the reanastomosis site to the two root bundles on one side. Electrodes were implanted bilaterally immediately proximal to the site of surgical reanastomosis. Results were compared to four root-intact, control animals that also received bilateral electrode implantation. At 6-12 months post-surgery, five of eight nerve transected and repaired animals showed increased pressure and bladder emptying during electrical stimulation of the repaired ventral roots contralateral to the BDNF delivery side. Nerve tracing studies one year postoperatively determined the repaired roots to be S1 and S2 and showed regrowth of axons from the spinal cord to nerve sites proximal to the repair site and to the bladder, and the presence of neurofilament-labeled axons growing across the ventral root repair site. In conclusion, transected ventral and dorsal roots in the sacral spine can be repaired and are capable of functionally reinnervating the urinary bladder. This feasibility study paves the way for future studies utilizing other more proximal motor nerves to bypass the transection site for bladder reinnervation.

Establishing Normal Values of the Proximal Median Motor Nerve−A Study of the Pronator Teres and Flexor Carpi Radialis in Healthy Volunteers

The importance of normative peripheral nerve data is increasing due to advances in medical implantation, microsurgical suturing, and tubulization repair techniques. Because the median nerve is often affected, its normal values must be reliable. Although the distal portion of the median nerve has been well studied using electrodiagnostic methods, the proximal forearm segment has not. This study establishes a normative database for median nerve conduction to the pronator teres (PT) and to the flexor carpi radialis (FCR). Two hundred-eight asymptomatic subjects were studied using proximal median motor stimulation at 10 cm. Latencies, amplitudes, areas, and durations were recorded. To the pronator teres: The upper limit for normal (ULN) motor latency was 3.5 ms (2.9 +/- 0.3 ms). The side-to-side latency difference was </= 0.5 ms. Overall, the lower limit of normal (LLN) amplitude was 2.2 mV. However, this decreased to 1.5 mV in the over-50 age group. To the flexor carpi radialis: The ULN motor latency was 3.6 ms (2.8 +/- 0.4 ms). The side-to-side latency difference was </= 0.7 ms. Overall, the LLN amplitude was 2.3 mV. However, this decreased to 1.7 mV in the over-50 group. This study produced a large database of normal results for the median motor nerve conduction to the pronator teres and to the flexor carpi radialis. The 10-cm techniques are easily reproducible and helpful when evaluating this portion of the median nerve.

Blocs de conduction nerveuse et neuropathies

A motor nerve conduction block is defined as a reduction of either amplitude or area of the compound motor action potential elicited by proximal vs. distal motor nerve stimulation. The pathophysiological mechanisms leading to a figure of conduction block include segmental demyelination, recent axonal interruption, or various axonal excitability abnormalities due to ion channel dysfunction or membrane potential changes. These processes can be related to compressive, ischemic or dysimmune inflammatory causes. The etiologic diagnosis is established on the combination of clinical, electrophysiological, and biological data. Among the neuropathies that feature nerve conduction blocks, there is a group of particular dysimmune multifocal neuropathies characterized by long-term persistent conduction blocks, including pure motor forms and sensori-motor forms. The clinical, electrophysiological, biological, and therapeutic specificities of these two types of neuropathy will be discussed.

0346 Terminal latency index of the median nerve: normal values and relation to Carpal Tunnel Syndrome

Background: The terminal latency index (TLI) is a calculated value that adjusts the distal motor latency for the terminal distance and the proximal motor nerve conduction velocity. The purpose of this study is to evaluate the sensitivity of the median TLI in the diagnosis of carpal tunnel syndrome (CTS) and compare it with other electrophysiological parameters. Methods: We prospectively studied 32 patients with nerve conduction studies using a conventional surface technique in the median and ulnar nerves. The distal distance for the CMAP was measured in 5 cm using Oh's techniques. Based on the clinical diagnosis, 32 patients (59 hands) were judged to have CTS. Control data were obtained from 40 healthy hands utilizing identical techniques. Results: The mean TLI was 0.240.04 in the CTS group and 0.300.02 in the control group (P13 years; 73% women). Twenty subjects with an average age of 46 years (SD15 years; 65% women) were evaluated for control data. The calculated lower limit of normal from the control group (mean-2SD) was 0.26. The sensitivity of the TLI was 73%. The TLI was statistically better than the median motor distal latency and sensory nerve conduction velocity in the second digit-wrist segment. In four patients from the CTS group, the TLI was the only abnormal electrophysiological parameter. Conclusions: The median TLI is an easy, inexpensive, highly informative test and is therefore extremely useful in the diagnostic work-up of patients with CTS.

Proximal nerve conduction by high-voltage electrical stimulation in S1 radiculopathies and acquired demyelinating neuropathies.

To evaluate the reliability and sensitivity of the high-voltage electrical stimulation for studying proximal conduction of peripheral motor axons in normal subjects, S(1) radiculopathies and acquired demyelinating neuropathies. Twelve patients with compressive S(1) radiculopathy, 22 patients with acquired demyelinating neuropathy and 29 healthy volunteers were examined. The conduction of peripheral motor axons between lumbosacral roots and the sciatic nerve at the gluteal fold was investigated by high-voltage electrical stimulation delivered percutaneously. The main electrophysiological finding in S(1) radiculopathy was an abnormal side to side difference in the amplitude of the compound motor action potential by proximal stimulation. Overall, the frequency of abnormalities detected by using high-voltage electrical stimulation was similar to that found with conventional EMG studies, and the two methods showed electrophysiological alterations in the same patients. In all patients with acquired demyelinating neuropathy, the proximal motor nerve conduction velocity from lumbosacral roots to the sciatic nerve at the gluteal fold was reduced; proximal stimulation of the motor axons revealed electrophysiological abnormalities more often than when using other electrophysiological techniques (F wave and H reflex). High-voltage electrical stimulation of peripheral motor axons shows high sensitivity in detecting proximal neuropathies; it can also define the site and relevance of proximal lesions in the peripheral nervous system better than other conventional techniques.

Proximal motor conduction evaluated by transcranial magnetic stimulation in acquired inflammatory demyelinating neuropathies

Objectives: To evaluate conduction abnormalities in the proximal motor nerve in patients with acquired inflammatory demyelinating neuropathies by transcranial magnetic stimulation (TMS). Methods: TMS intensity and background voluntary contraction (BVC) to evoke maximal size of motor evoked potential (MEP) in hand muscle were investigated in 24 normal subjects. Effect of experimentally induced conduction block by injecting local anesthetics in the peripheral nerve on MEP size was also studied in two normal subjects. In 22 patients with inflammatory demyelinating neuropathies, maximal MEPs were recorded in the deteriorating and recovery stages of the illness. Results: In normal subjects, the MEP became maximal with 30–50% of maximal BVC and at more than 80% the maximal stimulator output of the 2.0 T circular coil. The change in MEP size well reflected the degree of conduction block induced by local anesthetics. Findings for patients suggested conduction abnormalities proximal to axilla in 9 patients, and that the abnormal reduction of Erb CMAP was the result of submaximal stimulation, not true conduction block, in 3 patients. The increase in MEP/wrist CMAP ratio was better correlated with improvement in muscle strength than with change in the axilla or Erb CMAP/wrist CMAP ratio. Conclusions: Problems such as conduction abnormalities in the motor tract of the central nervous system could not fully be excluded, but we consider that maximal MEP size can be used to predict proximal motor nerve conduction abnormalities.

Proximal and distal motor nerve conduction in obturator and femoral nerves

Uludag B, Ertekin C, Turman AB, Demir D, Kiylioglu N. Proximal and distal motor nerve conduction in obturator and femoral nerves. Arch Phys Med Rehabil 2000;81:1166-70. Objective: To study the proximal and distal motor conduction properties of obturator and femoral nerves. Design: For evaluation of distal motor conduction properties, obturator and femoral nerves were stimulated at the inguinal ligament, and M responses were recorded with needle electrodes from gracilis and rectus femoris muscles. Upper lumbar roots were stimulated with needle electrodes inserted between L1-L2 vertebral laminae. Participants: Sixteen healthy adults, eight of each gender, age 22 to 52 years (mean 37.5). Main Outcome Measures: Description of a method for assessing motor conduction along the obturator nerve and evaluating proximal motor conduction measurements obtained with stimulation of obturator and femoral nerves. Results: Distal motor conduction latencies were 3.9 ± 0.7 msec for gracilis and 4.6 ± 0.5msec for rectus femoris after stimulation of obturator and femoral nerves, respectively. Proximal conduction times from lumbar vertebral level were 10.4 ± 0.3msec for the obturator nerve and 10.8 ± 0.4msec for the femoral nerve. Conduction velocities of proximal segments of both nerves were similar, 62m/sec for the obturator nerve and 65m/sec for the femoral nerve. Submaximal stimulation of both nerves evoked H-reflex responses from their associated muscles. Conclusions: Motor conduction properties of the obturator nerve can be assessed by the method described, particularly to differentiate between peripheral, plexus, or radicular lesions that involve the obturator nerve. © 2000 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation