Pilot study of a novel transmembranous electromyography device for assessment of oral cavity and oropharyngeal muscles.

INTRODUCTION/AIMS: Electromyography (EMG) can provide valuable insights into the pathophysiology of oropharyngeal muscles in various disease states, but the invasive nature of the conventional needle EMG (nEMG) has its limitations in this setting. We aimed to examine the inter-rater reliability (IRR) of a novel transmembranous EMG (tmEMG) sensor as a non-invasive technique for assessment of oral cavity and oropharyngeal muscles for neuromuscular pathology. METHODS: The study was a prospective, cohort, pilot study with blinded data analysis in healthy participants (n = 6), patients with moderate to severe obstructive sleep apnea (OSA) (n = 5) and bulbar amyotrophic lateral sclerosis (ALS) (n = 5). Each patient underwent sampling from bilateral palatoglossus (PG) and genioglossus (GG), using both tmEMG and nEMG. IRR was expressed as percentage agreement and prevalence-adjusted bias-adjusted kappa coefficient (PABAK). RESULTS: Substantial IRR was found for participants with ALS (81.6%, PABAK 0.63) and OSA (78.8%, PABAK 0.61), and in healthy participants (87.1%, PABAK 0.74). A better IRR was seen with tmEMG (95.7%, PABAK 0.92) than with nEMG (73.9%, PABAK 0.48) for healthy participants and also for those with OSA. Studies from GG had higher IRR than PG. Only one participant had a minor adverse event (sore throat). DISCUSSION: The current study shows that analysis of PG and GG in both healthy and disease states using tmEMG has high IRR compared with nEMG analysis. Further validation studies can be undertaken to test its utility in analysis of oral cavity and oropharyngeal muscles.

A neurophysiological approach to nerve transfer to restore upper limb function in cervical spinal cord injury.

A successful nerve transfer surgery can provide a wealth of benefits to a patient with cervical spinal cord injury. The process of surgical decision making ideally uses all pertinent information to produce the best functional outcome. Reliance on clinical examination and imaging studies alone can miss valuable information on the state of spinal cord health. In this regard, neurophysiological evaluation has the potential to effectively gauge the neurological status of even select pools of anterior horn cells and their axons to small nerve branches in question to determine the potential efficacy of their use in a transfer. If available preoperatively, knowledge gained from such an evaluation could significantly alter the reconstructive surgical plan and avoid poor results. The authors describe their institution's approach to the assessment of patients with cervical spinal cord injury who are being considered for nerve transfer surgery in both the acute and chronic setting and broadly review the neurophysiological techniques used.

Novel High-Frequency Peripheral Nerve Stimulator Treatment of Refractory Postherpetic Neuralgia: A Brief Technical Note.

OBJECTIVES: The study aims to describe an ultrasound (US)-guided peripheral nerve stimulation implant technique and describe the effect of high-frequency peripheral nerve stimulation on refractory postherpetic neuralgia. MATERIALS AND METHODS: Following a cadaver pilot trial using US and confirmatory fluoroscopic guidance, a 52-year-old man with refractory left supraorbital neuralgia underwent combined US and fluoroscopic-guided supraorbital peripheral nerve stimulator trial. The patient was subsequently implanted with a percutaneous lead over the left supraorbital and supratrochlear nerve utilizing a high-frequency stimulation paradigm. RESULTS: At 9 months follow-up, the pain intensity had declined from a weekly average of 8/10 to 1/10 on the pain visual analog scale (VAS). After implant, both nerve conduction and blink reflex studies were performed, which demonstrated herpetic nerve damage and frequency-specific peripheral nerve stimulation effects. The patient preferred analgesia in the supraorbital nerve distribution accomplished with high-frequency paresthesia-free stimulation (HFS) at an amplitude of 6.2 mA, a frequency of 100-1200 Hz, and a pulse width of 130 µsec, to paresthesia-mediated pain relief associated with low-frequency stimulation. CONCLUSION: We report the implant of a supraorbital peripheral nerve stimulating electrode that utilizes a high-frequency program resulting in sustained suppression of intractable postherpetic neuralgia.

Fecal incontinence patients categorized based on anal pressure and electromyography: Anal sphincter damage and clinical symptoms.

BACKGROUND: Disruption of external anal sphincter muscle (EAS) is an important factor in the multifactorial etiology of fecal incontinence (FI). OBJECTIVES: We categorize FI patients into four groups based on the location of lesion in neuromuscular circuitry of EAS to determine if there are differences with regards to fecal incontinence symptoms severity (FISI) score, age, BMI, obstetrical history, and anal sphincter muscle damage. METHODS: Female patients (151) without any neurological symptoms, who had undergone high-resolution manometry, anal sphincter EMG, and 3D ultrasound imaging of the anal sphincter were assessed. Patients were categorized into four groups: Group 1 (normal)-normal cough EMG (>10 µV), normal squeeze EMG (>10 µV), and normal anal squeeze pressure (>124 mmHg); Group 2 (cortical apraxia, i.e., poor cortical activation)-normal cough EMG, low squeeze EMG, and low anal squeeze pressure; Group 3 (muscle damage)-normal cough EMG, normal squeeze EMG, and low anal squeeze pressure; and Group 4 (pudendal nerve damage)-low cough EMG, low squeeze EMG, and low anal squeeze pressure. RESULTS: The four patient groups were not different with regards to the patient's age, BMI, parity, and FISI scores. 3D ultrasound images of the anal sphincter complex revealed significant damage to the internal anal sphincter, external anal sphincter, and puborectalis muscles in all four groups. CONCLUSION: The FI patients are a heterogeneous group; majority of these patients have significant damage to the muscles of the anal sphincter complex. Whether biofeedback therapy response is different among different patient groups requires study.

Botulinum toxin injections for low-back pain and sciatica.

BACKGROUND: Adequate relief from low-back pain (LBP) is not always possible. Emerging evidence suggests a role for botulinum neurotoxin (BoNT) injections in treating pain disorders. Proponents of BoNT suggest its properties can decrease muscle spasms, ischemia and inflammatory markers, thereby reducing pain. OBJECTIVES: To determine the effects of botulinum toxin injections in adults with LBP. SEARCH STRATEGY: We searched CENTRAL (The Cochrane Library 2009, issue 3) and MEDLINE, EMBASE, and CINAHL to August 2009; screened references from included studies; consulted with content experts and Allergan. We included published and unpublished randomised controlled trials without language restrictions SELECTION CRITERIA: We included randomised trials that evaluated BoNT serotypes versus other treatments in patients with non-specific LBP of any duration. DATA COLLECTION AND ANALYSIS: Two review authors selected the studies, assessed the risk of bias using the Cochrane Back Review Group criteria, and extracted the data using standardized forms. We performed a qualitative analysis due to lack of data. MAIN RESULTS: We excluded evidence from nineteen studies due to non-randomisation, incomplete or unpublished data. We included three randomised trials (N =123 patients). Only one study included patients with chronic non-specific LBP; the other two examined unique subpopulations. Only one of the three trials had a low risk of bias and demonstrated that BoNT injections reduced pain at three and eight weeks and improved function at eight weeks better than saline injections. The second trial showed that BoNT injections were better than injections of corticosteroid plus lidocaine or placebo in patients with sciatica attributed to piriformis syndrome. The third trial concluded that BoNT injections were better than traditional acupuncture in patients with third lumbar transverse process syndrome. Both studies with high risk of bias had several key limitations. Heterogeneity of the studies prevented meta-analysis. There is low quality evidence that BoNT injections improved pain, function, or both better than saline injections and very low quality evidence that they were better than acupuncture or steroid injections. AUTHORS' CONCLUSIONS: We identified three studies that investigated the merits of BoNT for LBP, but only one had a low risk of bias and evaluated patients with non-specific LBP (N = 31). Further research is very likely to have an important impact on the estimate of effect and our confidence in it. Future trials should standardize patient populations, treatment protocols and comparison groups, enlist more participants and include long-term outcomes, cost-benefit analysis and clinical relevance of findings.

Semi-quantitative electromyography as a predictor of nerve transfer outcome.

OBJECTIVES: Evaluate correlation between donor nerve semi-quantitative electromyography (sqEMG) and strength outcome in nerve transfer surgery. METHODS: Retrospective review of pre-operative donor nerve semi-quantitative neurophysiology and post-operative recipient muscle force after at least one-year follow-up. The semi-quantitative technique is the average motor unit number estimate associated with needle recorded interference patterns in the donor muscle (IP-AMUNE), which was correlated with hand-held manometry, standardized as a percent of the contralateral arm, using multivariable linear regression with backward selection. RESULTS: Twenty-eight nerve transfer cases were included. The correlation between the donor nerve IP-AMUNE and the recipient muscle strength was moderate to strong and highly significant (r = 0.67, p < 0.001). Medical Research Council (MRC) grading did not predict strength (p > 0.54). CONCLUSIONS: IP-AMUNE is a good predictor of strength after nerve transfer surgery and should be considered in the evaluation and planning of patients undergoing nerve transfer to aid in donor nerve selection. SIGNIFICANCE: IP-AMUNE may significantly benefit those undergoing nerve transfer surgery for the restoration of movement.

Restoring balance in focal limb dystonia with botulinum toxin.

Focal task-specific dystonia of the hand is rare in the general population, where it usually manifests as writer's cramp, but seems relatively common among musicians. The disability may be so severe as to prevent writing altogether or to end a professional musician's career. The cause is usually unknown but it is thought to be primarily a basal ganglia disorder with dysfunction of cortical-striatothalamic-cortical circuits. Abnormalities have been found in cortical movement preparation, intracortical inhibition, sensory and motor maps, and patterns of cortical activation during movement. Much evidence supports disordered processing of sensory information with disturbed sensorimotor integration. Underlying this may be maladaptive neural plasticity mechanisms. Treatment is difficult. Oral medications are generally ineffective and have troublesome side-effects. Intensive rehabilitation techniques based on neural plasticity theory show promise but are rarely available and are time-intensive. Botulinum toxin injections appear to be effective in writer's cramp and musician's dystonia, at least initially; long-term benefit is less common. Despite definite improvement, some patients abandon treatment because the gain is insufficient for meaningful function: this is particularly so for musicians. Much of the benefit from botulinum toxin injection comes from simply reducing muscle overactivity through muscle paralysis, restoring balance to motor control. However, some evidence suggests that botulinum toxin injections can produce transient improvement in some of the various cortical abnormalities described, probably through alteration of sensory input from the periphery, by direct and indirect means. These changes in cortical function might be usefully combined with those brought about by sensorimotor retraining programs, but such studies are awaited.

Botulinum toxin treatment of adult spasticity : a benefit-risk assessment.

Injections of botulinum toxin have revolutionised the treatment of focal spasticity. Before their advent, the medical treatment for focal spasticity involved oral anti-spasticity drugs, which had decidedly non-focal adverse effects, and phenol injections. Phenol injections could be difficult to perform, could cause sensory complications and had effects that were of uncertain duration and magnitude. Furthermore, few neurologists knew how to perform them as they were mostly the province of rehabilitation specialists. Botulinum toxin can produce focal, controllable muscle weakness of predictable duration, without sensory adverse effects. Randomised clinical trials (RCTs) involving patients with spasticity resulting from a variety of diseases (mainly stroke and multiple sclerosis) have clearly shown that botulinum toxin type A (Dysport and Botox) can temporarily (for approximately 3 months) reduce spastic hypertonia in the elbow, wrist and finger flexors of the upper limbs, and the hip adductors and ankle plantar flexors in the lower limbs. The clinical benefits from this reduction of neurological impairment are best shown in the upper limb, with less disability of passive function and reduced caregiver burden. In the lower limbs, there is improved perineal hygiene from hip adductor injections. The benefits of reducing ankle plantar flexor tone are less well established. Pain is also reduced, possibly by mechanisms other than muscle weakness. Improved active function has not yet been clearly demonstrated in RCTs, only in open-label trials. The safety of botulinum toxin-A is impressive, with minimal (mainly local) adverse effects. There are little data on the use of botulinum toxin type B (Myobloc or Neurobloc) in spasticity and the only RCT that has examined this did not show tone reduction; dry mouth appeared to be a very common adverse effect. There are also very little data to allow a benefit-risk comparison of phenol and botulinum toxin injections; each have their clinical and technical advantages and disadvantages, and phenol is much less costly than botulinum toxin.

Anesthesia considerations for monitoring TCMEPs in adults diagnosed with poliomyelitis as children: a case report.

UNLABELLED: The use of transcranial motor evoked potentials (TCMEPs) to detect and hopefully prevent injury to the brain, spinal cord, and peripheral nerves intraoperatively has increased greatly in recent years. It is well established that in addition to certain anesthetic agents, patient factors such as advanced age, obesity, diabetes, hypertension, and a collection of neurological and neuromuscular diseases and disorders can greatly reduce or completely eliminate the ability to monitor TCMEPs effectively. One such disease, poliomyelitis (polio), is a highly contagious viral disease that has been mostly forgotten since its near-eradication through vaccination. Over the past three decades there has been increasing recognition of late onset neurological deterioration in individuals who were afflicted by, and apparently recovered from, paralytic poliomyelitis much earlier in life. This condition is known as post-poliomyelitis syndrome (PPS). Patients that appear to have fully recovered from polio, and those with PPS, may require special anesthetic considerations to facilitate effective TCMEP monitoring. CASE REPORT: We report the rapid loss of only lower extremity TCMEPs bilaterally during a C6-C7, C7-T1 ACDF in a 67-year-old female to treat left-sided C7-C8 radiculopathy and C6-T1 foraminal stenosis. The general anesthetic maintenance regimen of 0.3 MAC sevoflurane and 100 microg/kg/min propofol was paused, and a wake-up test was initiated. Full upper and lower extremity motor function was observed. A thorough review of the patient's medical history revealed the potential risk factor of full recovery from poliomyelitis as a child. The sevoflurane was removed from the anesthetic regimen, and the lower extremity TCMEPs returned and were present for the remainder of the surgery.

Quantification of motor unit action potential energy.

OBJECTIVE: Motor unit action potentials (MUAPs) recorded by needle electrode reflect the functional state of the motor unit and its force-generating capacity, and are usually described morphologically (e.g. amplitude, duration). However, since the purpose of motor unit activation is force generation, MUAP energy seems a more physically meaningful measurement. METHODS: MUAPs were obtained by multi-MUAP decomposition of real interference patterns taken from human patients with neurological diseases. The energy content of each MUAP was measured from a time-frequency representation (TFR), specifically the Choi-Williams distribution, and compared with the standard MUAP morphological measure, the Size Index. The sample included normal, neurogenic, and myopathic MUAPs, from 11 patients. RESULTS: There is an exponential distribution of energy within a sample of MUAPs and a strong exponential relationship between the Size Index and MUAP energy was observed. CONCLUSIONS: The energy content of a MUAP can be quantified and corresponds very well with the current quantitative standard. Energy is a possible addition to MUAP quantification. SIGNIFICANCE: MUAPs could be classified as having normal, large (neurogenic), or low (myopathic) energy. MUAP energy has direct physical and physiological meaning that reflects the force-generating capacity of the motor unit. Time-frequency analysis could also be used to study the specific frequency content of MUAPs and the energy of MUAPs within an interference pattern, without the need for decomposition.

Application of time-varying analysis to diagnostic needle electromyography.

Quantification in clinical, diagnostic electromyography (EMG) currently includes motor unit action potential (MUAP) analysis and interference pattern analysis. Early efforts to examine the frequency/power spectra of the interference pattern showed modest value but the technique was not developed further. This paper re-examines spectral analysis, extending it into the time-varying domain, which has never been studied in diagnostic needle EMG. Time-frequency and time-scale analysis employing wavelet and non-wavelet techniques were applied to short trains of MUAPs. The results show that time-varying analysis produces clear visual representations of the energy content of individual MUAPs within an interference pattern. The time frequency representations allow easy, qualitative distinction between normal and neurogenic MUAPs. Furthermore, the quantified MUAP energy correlates well with the current morphological standard and the quantification process is substantially faster. Time-varying analysis links classical power spectral analysis in the realm of interference patterns with quantitative MUAP analysis. In addition to morphological classification, MUAPs might also be classified by energy content, which more closely reflects the physical and physiological consequences of neuromuscular pathology on the motor unit.

A self-referential outlier detection method for quantitative motor unit action potential analysis.

Quantitative MUAP analysis is often based on outlier detection, in the case of neurogenic conditions, the finding of MUAPs that are larger than the limit determined from a reference normal population. Such reference data is available from only a few sources and for only a few muscles. It would be desirable if muscles could serve as their own controls. The Henneman size principle determines the order of recruitment, following an exponential distribution of twitch force, motor neurone, motor unit, and MUAP size. Therefore, an outlier could be detected by being too large for the level of recruitment, as judged by its size relative to the other MUAPs. This would improve the sensitivity of detecting neurogenic muscles and obviate the need for external reference data.

The clinical practice of reconstructive neurosurgery.

Surgical interventions to improve function following nervous system injury have been in development since the early 1900s. Only recently these have been assimilated into a coherent approach which can be applied to injuries of the brain, spinal cord and peripheral nerves. In addition to pharmacological and stimulation based interventions, surgical manipulation of the peripheral nerves and muscles of the extremity can offer functional enhancement for a variety of limb impairments. In order to plan an effective surgical intervention, neurophysiological assessment of the injury and residual motor control is essential. Effective implementation of these surgical interventions can enhance function and quality of life for many individuals whose activity has been limited as a result of nervous system injury.

Spastic hypertonia and movement disorders: pathophysiology, clinical presentation, and quantification.

A delayed consequence of a lesion affecting the upper motor neuron pathways is the appearance of some forms of motor overactivity, including spasticity. Many of these are caused by hyperexcitability of spinal reflexes, such as stretch reflexes (spasticity, tendon hyperreflexia) or flexor withdrawal reflexes (flexor spasms), and are elicited at rest by sensory stimulation. Spastic co-contraction is probably attributable to failure of reciprocal inhibition; it occurs only during active voluntary movement and constrains such movement. The basic underlying mechanism of these changes is not clear, although a change in the balance between the inhibitory and excitatory supraspinal upper motor neuron pathways toward net excitation most likely contributes. Increased intrinsic excitability of the alpha motor neurons is another possible factor. Spastic dystonia is most often seen as the presence of tonic muscle contraction in the absence of voluntary movement or spinal reflex activation, and the underlying mechanisms are obscure. Prolonged shortening of tissues, either because of weakness or muscle contraction, leads to stiffness of the soft tissues, which contributes to hypertonia and is thus self-perpetuating, and ultimately to contracture with fixed shortening. Some of these forms of motor overactivity produce involuntary movements (hyperkinetic), eg, flexor spasms, whereas others impair movement (hypokinetic), either voluntary movement, eg, spastic co-contraction, or passive movement, eg, spasticity. Quantification has mostly focused on hypertonia, that is, increased resistance at rest to passive movement. In the upper motor neuron syndrome, hypertonia could be caused by a combination of spasticity, spastic dystonia, and soft tissue stiffness (rheologic changes). Some measures, such as the Ashworth or Modified Ashworth Scales, quantify hypertonia but are very poor at distinguishing between spasticity and soft tissue stiffness. Another, the Tardieu Scale, is better at making this distinction, but quantification of the spasticity portion of hypertonia remains difficult, at least in a clinical setting.

Response of the dropped head/bent spine syndrome to treatment with intravenous immunoglobulin.

Weakness of neck extension causing a dropped head may result from many neuromuscular disorders. One etiology is isolated neck extensor myopathy. A similar focal myopathy of the lower axial muscles may cause the bent spine syndrome, which manifests as flexion of the trunk and inability to stand upright. Combination of both dropped head and bent spine myopathies is uncommon. Inflammation is usually not pronounced in these conditions and response to immunosuppressive treatment is rare. We present an 81-year-old man who developed progressive weakness of neck and trunk extension over several months, with a prominent inflammatory process in the thoracic paraspinal muscles, which responded dramatically to treatment with intravenous immunoglobulin (IVIg). This case, together with other rare reports, suggests that the presence of inflammation in the biopsy of an affected muscle may predict treatment response.