Enteral tube feeding for amyotrophic lateral sclerosis/motor neuron disease

BACKGROUND

Enteral feeding (tube feeding) is offered to many people with amyotrophic lateral sclerosis/motor neuron disease experiencing difficulty swallowing (dysphagia) and maintaining adequate nutritional intake leading to weight loss.

OBJECTIVES

The aim of this review is to examine the efficacy of percutaneous endoscopic gastrostomy placement or other tube feeding placement on: (1) survival; (2) nutritional status; (3) quality of life. Another aim is to examine the minor and major complications of percutaneous endoscopic gastrostomy.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group Trials Register (June 2005), MEDLINE (from January 1966 to June 2005), and EMBASE (from January 1980 to June 2005) for randomized controlled trials. In addition we searched MEDLINE (January 1966 to June 2005) and EMBASE (January 1980 to June 2005) to identify non-randomized studies that might be worthy of review and discussion. We checked references in published articles, proceedings of scientific meetings, and enlisted personal communications to identify any additional references.

SELECTION CRITERIA

All randomized and quasi-randomized controlled trials were to have been selected. Since no such trials were discovered, all prospective and retrospective controlled studies were reviewed in the 'Background' or 'Discussion' sections of the review.

DATA COLLECTION AND ANALYSIS

We independently assessed study methodological design and extracted data. We considered the following outcomes: (1) survival rate in months (of primary interest), (2) nutritional status measured by weight change, change in body mass index, or other quantitative index of nutritional status, and (3) self-perceived quality of life We were also interested in reports of safety of the procedure as indicated by (4) minor and major complications of percutaneous endoscopic gastrostomy or other feeding tube placement.

MAIN RESULTS

We found no randomized controlled trials comparing the efficacy of enteral tube feeding with those people who continued to eat orally, without enteral feeding. We summarized the results of retrospective and prospective case controlled studies in the 'Discussion' section of this review.

AUTHORS' CONCLUSIONS

There are no randomized controlled trials to indicate whether enteral tube feeding is beneficial compared to continuation of oral feeding for survival. The 'best' evidence to date, based on controlled prospective cohort studies, suggests an advantage for survival in all people with amyotrophic lateral sclerosis/motor neuron disease, but these conclusions are tentative. Evidence for improved nutrition is also incomplete but tentatively favorable. Quality of life has only been addressed by a few researchers and needs more serious attention.

The effects of executive and behavioral dysfunction on the course of ALS

OBJECTIVE

To determine whether patients with ALS-frontotemporal lobar dementia (FTLD) have a shorter survival and are less compliant with recommended treatments than those with ALS who have normal executive and behavioral function (classic ALS).

METHODS

Survival analysis from ALS symptom onset to death included 81 of 100 consecutive patients who could be classified definitely as ALS with abnormal executive or behavioral function or as classic ALS. Criteria were defined for compliance with noninvasive positive-pressure ventilation (NPPV) and percutaneous endoscopic gastrostomy (PEG).

RESULTS

Median survival was 2 years 4 months for the 28 patients with FTLD and 3 years 3 months for the 53 patients with classic ALS (relative hazard for death 1.93, CI 1.09 to 3.43; p = 0.024). However, the relative hazard associated with FTLD (1.49) in the multivariate model was diminished by the association of FTLD with bulbar onset and older age and was not significant in this sample size. With bulbar onset, median survival was 2 years 0 months for the 14 with ALS-FTLD and 2 years 10 months for the 10 with classic ALS (relative hazard for death 2.78, CI 1.02 to 7.55; p = 0.045), and older age was not a significant risk. Noncompliance with NPPV and PEG were 75% and 72% in ALS-FTLD, respectively, vs 38% and 31% in classic ALS (relative risks 2.00 and 2.34; p = 0.013 and 0.022).

CONCLUSIONS

Survival is significantly shorter among patients with ALS-FTLD than with classic ALS. Furthermore, patients with ALS-FTLD are twice as likely to be noncompliant.

Treatment of pseudobulbar affect in ALS with dextromethorphan/quinidine: A randomized trial

BACKGROUND

Patients with ALS commonly exhibit pseudobulbar affect.

METHODS

The authors conducted a multicenter, randomized, double-blind, controlled, parallel, three-arm study to test a defined combination of dextromethorphan hydrobromide (DM) and quinidine sulfate (Q) (AVP-923) for the treatment of pseudobulbar affect in ALS. Q inhibits the rapid first-pass metabolism of DM. The effects of AVP-923 (30 mg of DM plus 30 mg of Q) given twice daily for 28 days were compared with those of its components. Patients were evaluated on days 1, 15, and 29. The primary efficacy variable was the change from baseline in the Center for Neurologic Study Lability Scale (CNS-LS) score. Secondary efficacy variables were laughing/crying episode rates and changes in Visual Analog Scales for Quality of Life (QOL) and Relationships (QOR). Efficacy was evaluated in intention-to-treat subjects who were not poor metabolizers of DM (n = 65 for AVP-923, n = 30 for DM, and n = 34 for Q). Safety was assessed in all randomized subjects (n = 140).

RESULTS

AVP-923 patients experienced 3.3-point greater improvements in CNS-LS than DM patients (p = 0.001) and 3.7-point greater improvements than Q patients (p < 0.001). AVP-923 patients exhibited lower overall episode rates, improved QOL scores, and improved QOR scores (p < 0.01 for all endpoints). Adverse effects were mostly mild or moderate; treatment-related discontinuation was 24% for AVP-923, 6% for DM, and 8% for Q.

CONCLUSIONS

AVP-923 palliates pseudobulbar affect in ALS. Overall benefits of treatment are reflected in fewer episodes of crying and laughing and improvements in overall quality of life and quality of relationships.

Are amyotrophic lateral sclerosis patients cognitively normal?

BACKGROUND

Patients with ALS are often told that the disease spares cognition; however, recent evidence suggests deficits in frontal executive skills occur in a sizable minority of ALS patients. In many instances, the frontal executive deficits represent the co-occurrence of frontotemporal lobar dementia (FTLD) and ALS.

METHODS

Word generation, a simple frontal task that takes <2 minutes, was tested in 100 consecutive patients with ALS seen in the authors' multidisciplinary clinic. Any patient with a prior dementia diagnosis was excluded from the study. A subset of 44 patients agreed to undergo further neuropsychological testing and clinical interview to confirm or deny a diagnosis of dementia.

RESULTS

Diminished word generation was found in one-third. Of the patients with abnormal word generation who agreed to further evaluation, nearly all were shown to meet research criteria for FTLD. In addition, one-quarter of the patients with normal word generation who agreed to further evaluation met research criteria for FTLD; these patients had new-onset personality changes.

CONCLUSIONS

This study suggests that frontal executive deficits are present in half of ALS patients, many of whom meet strict research criteria for FTLD. Word generation tests are a useful screening tool in this cohort.

Effect of recording window and stimulation variables on the statistical technique of motor unit number estimation

A variety of methods are used for the selection of recording window sizes and stimulation current levels for statistical motor unit number estimation (MUNE). This study compares different recording window sizes and stimulation current levels within those windows in the same subjects to determine the effect on MUNE value and reproducibility. Four recording windows of 10% size were compared with four of 5%, with the stimulation current set in the lower quarter, middle half, and upper quarter of the recording window. MUNE for stimulation current set in the lower quarter of the window was 81 (62-103) for 10% recording windows and 120 (108-135) for 5% recording windows, and 91 (61-123) and 133 (120-154) for stimulation current set in the middle half. Increasing the recording window size from 5 to 10% lowers the MUNE value in controls, but tends to improve reproducibility; and setting the stimulation current in the lower quarter of the window, changes the MUNE value minimally, while tending to improve further reproducibility. Excellent reproducibility of MUNE was obtained when applied to a pilot group of 10 amyotrophic lateral sclerosis patients. Based on this study, we conclude that the ideal method for statistical motor unit estimation involves using 10% recording windows and setting the stimulation current in the lower quarter of the recording window.

Comparison of multiple point and statistical motor unit number estimation

This study compares two common techniques for motor unit number estimation, multiple point stimulation and statistical method, to determine which is more reproducible. Surface recorded motor unit action potentials (SMUPs) of the left hypothenar muscle group were measured on 20 controls and 10 ALS patients. For multiple point, 10 different threshold SMUPs were recorded. For statistical method, mean SMUP amplitude was measured at several stimulus levels, typically spanning >40% of CMAP amplitude range. Both techniques were performed twice, results averaged, electrodes changed, and all recording repeated. For controls, mean of two motor unit number estimation (MUNE) (+/- standard deviation) was 60 (+/-5) for statistical method, and 108 (+/-38) for multiple point. For ALS patients, these values were 21 (+/-16) for statistical method and 55 (+/-39) for multiple point. Test-retest correlation coefficients and coefficients of variation for mean of two MUNE were 0.98 and 7% for statistical method, and 0.90 and 12% for multiple point, respectively. Statistical method was more reproducible and faster than multiple point, supporting its utility in monitoring rates of MUNE change.

Motor unit number estimation (MUNE): how may it contribute to the diagnosis of ALS?

Motor unit number estimation (MUNE) is a type of electrophysiological technique that measures the approximate number of lower motor neurons (LMNs) innervating a single muscle or a small group of muscles. Low MUNE counts provide evidence of LMN degeneration, but a single MUNE study does not determine if this loss is ongoing, recent or remote in time. Sequential change of MUNE count provides evidence for ongoing degeneration. Furthermore, sequential change in MUNE from a normal to abnormally low count provides evidence for progressive spread of signs within a region or to another region. MUNE has no established ability to identify other diseases that may provide a non-ALS explanation for the signs of LMN degeneration. If MUNE studies were to be incorporated into a future revision of the diagnostic criteria for ALS, prospective studies will be important to define more clearly the sensitivity and specificity of MUNE in patients with ALS and in patients with weakness that does not involve LMN degeneration. In addition to its potential contributions toward the diagnosis of ALS, MUNE may have greater potential in quantifying the rate of progression in studies of the natural history of ALS and the response to experimental treatment.

Statistical motor unit number estimation: reproducibility and sources of error in patients with amyotrophic lateral sclerosis

The reliability of motor unit number estimation (MUNE) for assessment of the long-term course of ALS is dependent on the reproducibility of the technique. We report our results with the statistical method of MUNE on the ulnar nerve/hypothenar muscle in 16 ALS patients who were studied on 52 occasions. On each occasion, MUNE was performed twice with one electrode placement and once with a different placement. For each MUNE, mean surface motor unit potential amplitude was determined within three different recording ranges or windows at different stimulus intensities. The MUNE results had excellent reproducibility with coefficients of variation of 19% and test-retest correlation coefficients from 0.75 to 0.86. With examination of sources for variability, the reproducibility of statistical MUNE is not affected by minor variation in stimulation and recording electrode placement but may be improved by modifying methods for recording window selection. The high reproducibility of statistical MUNE supports its reliability for estimating the rate of motor unit loss in ALS.

Neuropathies associated with connective tissue disease

Neuropathies are a common neurologic manifestation of diffuse connective tissue disease. Vasculitic neuropathy requires prompt diagnosis and treatment to improve its outcome. It is commonly multifocal but may be confluent and symmetrical. Vasculitic neuropathy needs to be distinguished from the more common syndromes of compression neuropathy, which may also be multifocal, and nonvasculitic distal axonal polyneuropathy. Sensory neuronopathy is a distinctive syndrome unique to Sjögren's syndrome among the connective tissue diseases. Trigeminal sensory neuropathy may be the presenting feature of systemic sclerosis or may develop during the course of other connective tissue diseases. This article reviews the clinical and diagnostic features of neuropathies associated with the common diffuse connective tissue diseases.

Clinical trials for polyneuropathy: the role of nerve conduction studies, quantitative sensory testing, and autonomic function testing

Clinical trials to assess the treatment of diabetic and other forms of polyneuropathy are becoming increasingly common. Nerve conduction studies, quantitative sensory testing, and autonomic function testing are often used in these trials. This article reviews the sensitivity and reproducibility of these measures to detect change in peripheral nerve function during long-term trials. The attributes of nerve conduction studies that are likely to be most useful are summated or averaged sensory nerve action potential amplitudes and averaged motor nerve conduction velocities. Summated or averaged compound muscle action potential amplitude and mean F-wave latencies are also highly informative. Vibratory detection thresholds are sensitive, specific, and highly reproducible for assessment of large myelinated sensory fibers, with cooling and warming detection thresholds also having good sensitivity for small myelinated sensory fibers. Although less well validated for longitudinal trials, visual analogue scale scoring of heat pain provides assessment of unmyelinated sensory fibers. Heart rate variation to deep breathing, Valsalva, or standing are useful to assess cardiac autonomic function. Based on these data that are reviewed and consistent with the conclusions of previous consensus conferences, a combination of these studies is recommended.

Longitudinal study of fiber density and motor unit number estimate in patients with amyotrophic lateral sclerosis

We examined fiber density, compound muscle action potential (CMAP) amplitude, and motor unit number estimate (MUNE) of the abductor digiti minimi and grip strength longitudinally. We sought to determine the effects of ALS on these measurements and to evaluate which of these tests may be more sensitive in evaluating progression of ALS and possibly predicting survival. Ten patients were examined at months 0, 3, and 6. A significant decrease in MUNE and increase in fiber density were observed at months 3 and 6 (p < 0.02) compared with baseline (month 0). Mean CMAP and grip strength declined, but not significantly. The decrease in MUNE over 6 months was significantly greater than that of CMAP and grip strength (p < 0.025). The significant changes in MUNE and fiber density over time suggest that they are more sensitive in measuring the rate of progression of ALS. To evaluate further the utility of these tests, we arbitrarily divided the patients into equal groups based on length of survival. MUNE declined significantly in the group with shorter survival (p < 0.01). Conversely, fiber density increased significantly in patients with longer survival (p < 0.01). With similar statistical analysis there were no significant differences in decline of CMAP or grip strength in either subgroup over 6 months. Our study suggests that MUNE and fiber density are more sensitive than CMAP and grip strength in detecting progression of ALS. Furthermore, we raise the hypotheses that a greater increase in fiber density identifies a group of patients with ALS who will have longer survival, and that a greater decline in MUNE identifies a group with a worse prognosis.

Serum IgM monoclonal autoantibody binding to the 301 to 314 amino acid epitope of beta-tubulin: clinical association with slowly progressive demyelinating polyneuropathy

We identified five patients with IgM monoclonal autoantibodies that bound to human brain tubulin. In a companion study, we found that IgM in these sera selectively recognized one of three epitopes on tubulin. IgM from three patients bound selectively to a small epitope on human beta-tubulin comprising amino acids 301 to 314. The other two sera recognized tubulin amino acids 215 to 235 and 315 to 336. In this study, we compared the clinical syndromes in these patients with the tubulin epitope recognized by their serum IgM. The three patients with IgM binding to tubulin amino acids 301 to 314 all had chronic inflammatory demyelinating polyneuropathy (CIDP) syndromes with slowly progressive weakness, hyporeflexia, and electrophysiologic studies consistent with demyelination. Two of these patients had significant asymmetry to their weakness. The two other patients had diagnoses of polyradiculopathy and amyotrophic lateral sclerosis with no evidence of peripheral nerve demyelination. We conclude that IgM monoclonal anti-tubulin antibodies have some association with demyelinating polyneuropathy syndromes, but may occur in patients with other clinical syndromes as well. A stronger association with demyelinating polyneuropathies may occur if the anti-tubulin antibodies recognize the 301 to 314 amino acid epitope on tubulin. This tubulin epitope, or a similar one on another molecule, could play an important antigenic role in the development of demyelinating polyneuropathies with features of CIDP.

Reduced corticomotoneuronal excitatory postsynaptic potentials (EPSPs) with normal Ia afferent EPSPs in amyotrophic lateral sclerosis

We studied excitatory postsynaptic potentials (EPSPs) arising in single spinal motoneurons (composite EPSPs) induced by Ia afferent and magnetic cortical stimulation in 28 normal subjects ranging in age from 24 to 84 years and 28 patients with amyotrophic lateral sclerosis (ALS) aged 34 to 82 years. The subjects voluntarily recruited single motor units of the first dorsal interosseous muscle. Using peristimulus time histograms, we determined changes in the firing probability of the first dorsal interosseous motor units and measured the magnitude of the EPSP. An early period of increased firing probability (primary peak) occurred at approximately 30 msec after la afferent and 25 msec after cortical stimulation, reflecting underlying EPSPs arising in spinal motoneurons induced by either projection. The latency of the primary peaks for both Ia afferent and cortical stimulation was mildly prolonged in ALS, suggesting a loss of the fastest-conducting spinal motoneurons. Patients with ALS had la afferent-driven EPSPs whose amplitude and rise time were equivalent to those of normal subjects. However, the ratio of cortical to la afferent-driven composite EPSPs in ALS was significantly lower than that for normal subjects. Fourteen of 28 ALS motor units had cortically driven EPSPs that were small or large only because of a prolonged rise time. The findings suggest that in ALS, corticomotoneuronal attrition or dispersion of the descending volley occurs in the presence of normally functioning spinal motoneurons to which they project.

Peptide T in the treatment of painful distal neuropathy associated with AIDS: results of a placebo-controlled trial. The Peptide T Neuropathy Study Group

OBJECTIVE

To assess the safety and efficacy of Peptide T in the treatment of painful distal symmetrical polyneuropathy (DSP) associated with human immunodeficiency virus (HIV) infection.

BACKGROUND

Painful DSP is a frequent complication of HIV infection, although its etiology and optimal treatment are unknown. Peptide T (D-(alpha 1)-Peptide T-amide) has been found in phase I trials and anecdotal reports to relieve neuropathic pain in AIDS patients.

DESIGN/METHODS

In this multicentered, double-blind, randomized study, subjects received intranasal Peptide T 6 mg/day or placebo for 12 weeks. The primary outcome measure was change in the modified Gracely pain score. Secondary efficacy variables were results of neurologic examination, neuropsychological and electrophysiologic studies, global evaluation, and CD4 lymphocyte counts.

RESULTS

Of 81 evaluable subjects, 40 received Peptide T and 41 received placebo. The change in pain scores was not significantly different (p = 0.32) in the Peptide T group (-0.24) as compared to placebo (-0.39). Group comparisons were not significantly different for change in any clinical examination or neuropsychologic measure, sural nerve amplitude or conduction velocity, or CD4 lymphocyte count. No significant drug-related adverse effects occurred in either group.

CONCLUSION

Intranasal Peptide T is safe but ineffective in the treatment of painful DSP associated with AIDS.

Neurologic complications of lumbar epidural anesthesia and analgesia

We reviewed the clinical features of 12 patients with neurologic complications following lumbar epidural anesthesia or analgesia. Eleven patients experienced lumbosacral radiculopathy or polyradiculopathy and, of these, 10 received epidural anesthesia or analgesia and one received subarachnoid injection of medication after intended epidural anesthesia. One patient suffered a moderately severe thoracic myelopathy in the setting of unintended spinal anesthesia. The two patients with more severe polyradiculopathy had severe lumbar spinal stenosis on MRI. The other patients experienced mild to moderate neurologic deficits most often involving the L-2 root, and MRIs, when performed, were unremarkable. EMG on three patients helped to localize the lesions to the lumbosacral roots and to quantify the extent of axonal loss. Ten patients were ambulatory upon discharge from the hospital and had good neurologic outcome. One patient with severe polyradiculopathy did not improve after 4 years and had severe motor axonal loss based upon electrodiagnostic studies. The patient with a thoracic myelopathy was ambulatory 4 months after onset. Although generally a safe procedure with low frequency of complications, lumbar epidural anesthesia or analgesia occasionally causes neurologic sequelae such as radiculopathy or myelopathy. Neurologic complications may be more severe in the presence of spinal stenosis or after inadvertent subarachnoid injection of anesthetic or analgesic agent.

The electrophysiologic features of sciatic neuropathy in 100 patients

We reviewed the electrophysiologic data of 100 consecutive patients with sciatic neuropathy in order to better understand this disorder. Most patients (93%) had electrodiagnostic signs of significant axonal loss. Seven patients had predominantly signs of demyelination; 6 were due to compression and 1 was idiopathic. The peroneal division was more severely affected than the tibial division in 64% of patients. Tibialis anterior EMGs were abnormal in 92%, and the EDB CMAP was low in amplitude or absent in 80%. CMAP and SNAP amplitudes and EMGs were all normal in the tibial division in 12%. In contrast, the tibial division was more severely affected in only 8 patients. Of those, 5 were due to thigh trauma (gunshot wounds or femur fracture), 2 from gunshot wounds to the hip, and the other was chronic and idiopathic. Sciatic neuropathies are commonly, but not always, axonal loss lesions that affect the peroneal greater than tibial division.

Sciatic neuropathy: clinical and prognostic features in 73 patients

We examined the clinical features of patients with sciatic neuropathy and the factors that influence prognosis. Of 92 consecutive patients referred for EMG evaluation of sciatic neuropathy, 73 fulfilled strict inclusion and exclusion criteria and had adequate clinical and electrophysiologic information. The etiologies included hip arthroplasty (21.9%), acute external compression (13.7%), infarction (9.6%), gunshot wound (9.6%), hip fracture/dislocation (9.6%), femur fracture (4.1%), contusion (4.1%), and uncertain (16.4%). We used life table analysis to determine outcome and to identify prognostic factors in patients with acute or subacute onset. Moderate or better recovery (improvement to grade 2 or by two of six clinical grades) occurred in most patients (30% by 1 year, 50% by 2 years, 75% by 3 years). A subgroup experienced excellent improvement (by three of six grades, or to grade 2) less frequently (33% by 2 and 3 years). Of the nine factors tested, two predicted an earlier or better recovery: a recordable compound muscle action potential of the extensor digitorum brevis (p < 0.025), and an initial absence of paralysis of muscles controlling ankle plantar flexion and dorsiflexion (p < 0.05). Thus, good but incomplete recovery occurs over 2 to 3 years in most patients with sciatic neuropathy, particularly in those without severe motor axonal loss.

Acute lumbosacral polyradiculopathy in acquired immunodeficiency syndrome: experience in 23 patients

We reviewed our experience in 23 patients with acquired immunodeficiency syndrome (AIDS) who had acute lumbosacral polyradiculopathy. The patients developed a distinctive syndrome of rapidly progressive flaccid paraparesis and areflexia that was frequently associated with sphincter disturbances. Persuasive laboratory evidence of a cytomegalovirus polyradiculopathy (polymorphonuclear pleocytosis or confirmatory cerebrospinal fluid culture) was found in 15 of the 23 patients. Treatment with ganciclovir in these patients led to clinical stabilization, although worsening during the first 2 weeks of treatment was common. Most patients with cytomegalovirus polyradiculopathy had severe residual deficits. Metastasis from systemic lymphoma accounted for the polyradiculopathy in 2 other patients. A more benign syndrome was identified in the remaining 6 patients. They generally had slower clinical progression and less severe neurological deficits at their nadir than did patients with cytomegalovirus polyradiculopathy. Unlike patients with cytomegalovirus infection, their cerebrospinal fluid showed a predominantly mononuclear pleocytosis. Moreover, spontaneous improvement without treatment was common. Our experience together with the published experience of others suggests that the acute lumbosacral polyradiculopathy in AIDS is a clinical syndrome with different etiologies and variable clinical outcome. Recognition of this heterogeneity is necessary for the management of individual patients, as well as the interpretation of treatment results.

High-titer selective serum anti-beta-tubulin antibodies in chronic inflammatory demyelinating polyneuropathy

Although chronic inflammatory demyelinating polyneuropathy (CIDP) is presumed to be an autoimmune disorder, no neural antigen has been recognized as an immune target. We found that serum IgM from a patient with CIDP and an IgM paraprotein reacted with a 53-kd protein by Western blot analysis. Amino acid sequence analysis identified this protein as beta-tubulin. We then studied sera from 70 CIDP patients, 35 Guillain-Barré syndrome (GBS) patients, and 483 disease (amyotrophic lateral sclerosis, Alzheimer's disease, multiple sclerosis, diabetes, and other polyneuropathies) and normal controls for selective high-titer anti-beta-tubulin using ELISA methodology. Forty-two percent (30/70) of patients with CIDP had selective high titer IgM reactivity against beta-tubulin; 23% (16/70) had selective high-titer IgG reactivity against beta-tubulin. Overall, 57% of CIDP patients, 20% of GBS patients, and 2% of control patients had selective, high serum IgM or IgG anti-beta-tubulin reactivity. Selective high-titer serum anti-beta-tubulin antibodies occur in a majority of patients with CIDP but are rare in other chronic neuropathies or CNS disorders.

Idiopathic, progressive mononeuropathy in young people

We describe six young patients with insidiously progressive, painless weakness in the distribution of a single major lower extremity nerve. No cause could be found despite extensive evaluation, including surgical exploration. At the time of diagnosis, all patients had weakness and three patients had sensory loss. In all cases, electromyography revealed a chronic axonal mononeuropathy without conduction block or focal conduction slowing. Magnetic resonance, computed tomographic, and ultrasound imaging studies did not identify a region of nerve swelling, mass, or compression. At surgical exploration, the nerve appeared atrophic in two patients, indurated in one patient, and normal in two patients. Biopsy specimens obtained from two abnormal nerves revealed either wallerian degeneration or endoneurial fibrosis. The clinical features of these patients comprise an unusual clinical entity with no known cause or treatment.

Peripheral neuropathies associated with human immunodeficiency virus infection

In the 1990s, HIV has replaced syphilis as the "great masquerader." Virtually every level of the neuraxis may be affected in a patient with HIV infection. The superimposition of multiple levels of neuropathology further complicate the bedside neurologic diagnosis of an AIDS patient. This article has reviewed the variety of forms of peripheral neuropathy that may be associated with HIV infection and its treatment. Distal symmetrical polyneuropathy may be produced in patients with HIV infection by neurotoxic drugs (e.g., vincristine, INH, ddC, or ddI) or by vitamin B12 deficiency or may develop in the later stages of HIV infection without identifiable cause. GBS and CIDP occur with increased frequency in early HIV infection owing to presumed autoimmunity, and these IDPs respond to plasmapheresis or prednisone, similar to HIV-seronegative patients. A limited distribution of mononeuropathy simplex or multiplex occurs in patients with CD4 counts greater than 200; the neuropathy will usually spontaneously improve in these patients. Widespread mononeuropathy multiplex may occur in patients with AIDS and CD4 counts less than 50 and is then usually caused by CMV infections; those neuropathies are usually progressive unless antiviral treatment is given. Progressive polyradiculopathy usually occurs in patients with AIDS and low CD4 counts. If the cerebrospinal fluid has a polymorphonuclear pleocytosis, CMV infection is almost always present, and progression is expected unless ganciclovir therapy is promptly started. Finally, mild autonomic neuropathy is commonly present in HIV-infected patients. Protocols for the evaluation and therapy of cranial and peripheral neuropathies are presented (Figs. 6 and 7). It is unfortunate but likely that increasing numbers of "neuro-AIDS" patients will be encountered, not only in urban medical centers but also in general community practice. The pace at which research in the field of HIV research has proceeded is unprecedented. It is, therefore, important that neurologists stay at the forefront of investigation and clinical care of these complex disorders.

The relative diagnostic sensitivity of different F-wave parameters in various polyneuropathies

We studied F-wave minimum latency, persistence, and chronodispersion in the median and ulnar nerves of 70 controls and 75 patients with various polyneuropathies. Prolonged minimum latency was the most frequent F-wave abnormality in all groups of patients with polyneuropathy. The finding of decreased persistence or absence of F-responses was comparable in sensitivity to prolonged minimum latency in Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP), whereas chronodispersion had a comparable sensitivity only in CIDP. Decreased persistence of obtained F-responses, and the absence of F-responses in nerves with low compound muscle action potential amplitudes, were nonspecific findings. F-wave studies often provide useful additional information in the evaluation of patients suspected of having a polyneuropathy. In patients with axonal polyneuropathies, we found that F-wave studies are significantly more sensitive than standard motor conduction studies in identifying physiological abnormalities of motor axons. Furthermore, in a patient with an acquired polyneuropathy, the finding of markedly prolonged minimum latency, or the absence of F-responses in nerves with normal CMAP amplitude, is highly specific for the presence of demyelination.

AAEM minimonograph #38: neuropathies in connective tissue disease

Neuropathies are common in patients with known or suspected connective tissue disease. A vasculitic mononeuropathy multiplex is often seen in patients initially presenting with polyarteritis nodosa or developing arteritis as a complication of rheumatoid arthritis. However, vasculitic neuropathy may become confluent and present as as distal symmetrical polyneuropathy or occur without systemic necrotizing vasculitis. Distal symmetrical polyneuropathies without associated vasculitis are also common in many connective tissue diseases. Compression neuropathies, especially carpal tunnel syndrome, occur with increased frequency in rheumatoid arthritis. Finally, certain neuropathies may be the major presenting feature of particular connective tissue diseases. For example, trigeminal neuropathy often heralds the onset of systemic sclerosis or mixed connective tissue disease, and sensory neuronopathy may be the initial presenting feature of Sjögren's syndrome.

Botulinum toxin therapy for limb dystonias

We investigated the effectiveness of botulinum toxin in 17 patients with limb dystonias (10 with occupational cramps, three with idiopathic dystonia unrelated to activity, and two each with post-stroke and parkinsonian dystonia) in a placebo-controlled, blinded study. We identified affected muscles clinically and by recording the EMG from implanted wire electrodes at rest and during performance of tasks that precipitated abnormal postures. There were three injections given with graded doses of toxin (average doses, 5 to 10, 10 to 20, and 20 to 40 units per muscle) and one with placebo, in random order. Subjective improvement occurred after 53% of injections of botulinum toxin, and this was substantial in 24%. Only one patient (7%) improved after placebo injection. Subjective improvement occurred in 82% of patients with at least one dose of toxin, lasting for 1 to 4 months. Response rates were similar between clinical groups. Objective evaluation failed to demonstrate significant improvement following treatment with toxin compared with placebo. The major side effect was transient focal weakness after 53% of injections of toxin.

Quantitative motor unit analysis: the effect of sample size

This study of quantitative electromyography examines the influence of sample size on motor unit action potential (MUAP) tolerance limits, intertrial variability, and diagnostic sensitivity. We recorded 20 randomly selected MUAPs from the biceps muscle twice in 21 normal subjects, and once in 10 patients with myopathy. The 95% tolerance limits for mean total duration in normal subjects progressively narrowed from 6.6 to 14.2 ms for 5 MUAPs to 7.4 to 13.0 ms for 20 MUAPs. The 95% tolerance limits for intertrial variability were +/-22% for mean total duration of 20 MUAPs. Larger sample size had a greater effect on reducing intertrial variability than on narrowing 95% tolerance limits for amplitude and area. Quantitative EMG results for duration supported the presence of myopathy in 2 of 10 patients with analysis of 5 MUAPs, and 9 patients with analysis of 20 MUAPs. Although analysis of 5 potentials may be adequate for diagnosis occasionally, quantitative analysis of 20 MUAPs narrows tolerance limits, reduces intertrial variability, and improves diagnostic sensitivity.

AAEM case report #23: acute paralytic poliomyelitis

A 56-year-old man with acute paralytic poliomyelitis is described. The illness started with fever and diarrhea after an overseas trip, and an enterovirus other than poliovirus was isolated from the patient's stool. The onset of weakness was rapid and asymmetric, with primary involvement of the lower extremities. Nerve conduction studies revealed low amplitude motor responses after the first week, with normal results for sensory studies. Serial electromyographic studies were performed, documenting acute denervation followed later by reinnervation in the distribution of multiple segments. The clinical and electrodiagnostic features of acute poliomyelitis are reviewed.

Clinical and electrodiagnostic features of X-linked recessive bulbospinal neuronopathy

We describe four men from two kinships affected with X-linked recessive bulbospinal neuronopathy, and one sporadic case. All developed postural tremor, weakness, and fasciculations, with onset from age 25 to 39 years. Weakness began in the pelvic girdle or hands, with dysphagia or dysarthria occurring years later in two. Sensory symptoms were present in only one, who also had diabetes mellitus. In contrast, sural nerve action potentials were small or absent in all. Needle EMG showed widespread chronic partial denervation with reinnervation. The characteristic twitching of the chin produced by pursing of the lips consisted of repetitive or grouped motor unit discharges, rather than fasciculations. Broader awareness of the distinctive features of bulbospinal neuronopathy will probably increase the frequency of its recognition. Diagnosis is important for purposes of providing a prognosis for affected men and genetic counseling for affected families.

Change in pattern of muscle activity following botulinum toxin injections for torticollis

Twenty patients with torticollis had electromyographic studies of their neck muscles performed before and after a series of local injections of botulinum toxin. The pattern of muscle activity changed after the injections, and this effect persisted even after head position had returned to baseline. Patients who did not experience any clinical benefit from the injections also demonstrated a change in the pattern of muscle activity. These results suggest that the underlying abnormality in torticollis usually involves a general motor program for head position, rather than the activity of individual neck muscles.

A comparison of thermography and electromyography in the diagnosis of cervical radiculopathy

We studied 20 asymptomatic control subjects and 14 patients with clinically unequivocal cervical radiculopathy to compare the diagnostic value of thermography with that of electromyography. We measured the average skin temperature of designated regions over the neck, shoulder, and upper extremities. We then compared the temperature between corresponding regions of the two limbs, and between fingers innervated by different roots in the same hand. Thermography was abnormal in 6 patients (43%), whereas electromyography was abnormal in 10 (71%). Thermographic abnormalities were seen only in the hands and fingers, and the pattern did not follow the dermatome of the clinically involved cervical root. When compared to electromyography, thermography provided no additional diagnostic information. Thus, thermography does not have an established role in the evaluation of patients with cervical radiculopathy.

A comparison of magnetic and electrical stimulation of peripheral nerves

We compared magnetic stimulation using different coil designs (2 rounded coils and a butterfly-prototype coil) with electrical stimulation of the median and ulnar nerves in 5 normal subjects. Using magnetic stimulation we were able to record technically satisfactory maximal sensory and motor responses only with the butterfly coil. Submaximal electrical stimuli preferentially activated sensory rather than motor axons, but submaximal magnetic stimuli did not. The onset latency, amplitude, area and duration of responses elicited electrically or magnetically with the butterfly coil during routine sensory and motor nerve conduction studies were similar, and motor and sensory conduction velocities were comparable when studied over long segments of nerve. However, the motor conduction velocities with magnetic and electrical stimulation differed by as much as 18 m/sec in the across-elbow segment of ulnar nerve. Thus, recent developments in magnetic stimulator design have improved the focality of the stimulus, but the present butterfly coil design cannot replace electrical stimulation for the detection of focal changes in nerve conduction velocity at common entrapment sites, such as in the across-elbow segment of the ulnar nerve.

Somatic mosaicism at the Duchenne locus

Results of testing a family for carrier status and prenatal diagnosis for Duchenne muscular dystrophy (DMD) are best explained by somatic mosaicism in the maternal grandfather. This genetic situation was identified using segregation analysis of intragenic DNA polymorphisms, a serum creatine phosphokinase assay, and physical examination of the patients. This event at the DMD locus represents one more potential source of error in carrier testing and prenatal diagnosis.

Electrodiagnostic features of the Guillain-Barré syndrome: the relative sensitivity of different techniques

We compared the diagnostic sensitivity of somatosensory evoked potentials (SEPs) and F waves with peripheral motor and sensory nerve conduction studies in 15 patients with the Guillain-Barré syndrome. All 4 types of studies were performed on 44 nerves (17 median, 12 ulnar, and 15 lower extremity). In the lower extremities, we used the peroneal nerves for all types of study except peripheral sensory conduction studies, which were performed on the sural nerve. We detected abnormalities by peripheral motor conduction studies in 33 of 44 nerves, by F waves in 31, by SEPs in 23, and by peripheral sensory conduction in 17. The cumulative sensitivity increased with the testing of multiple nerves by motor nerve conduction, sensory nerve conduction, and F-wave studies, but not with multiple SEPs. F-wave studies were significantly more sensitive than SEPs in identifying abnormalities. Thus, the recording of SEPs is indicated for diagnosis of the Guillain-Barré syndrome only if peripheral nerve conduction and F-wave studies are normal.

Lower motor neuron syndromes defined by patterns of weakness, nerve conduction abnormalities, and high titers of antiglycolipid antibodies

We studied 74 patients with progressive, asymmetrical lower motor neuron syndromes. Clinical features of these patients, including age, sex, disease duration, patterns of weakness, and reflex changes, were evaluated by review of records. In each patient the clinical features were compared to the type of nerve conduction abnormalities and to the specificities of high-titer serum antiglycolipid antibodies. Antibody specificities were determined by an enzyme-linked immunosorbent assay using purified glycolipids and carbohydrates as substrates. Our results show that high titers of antibodies to glycolipids are common in sera of patients with lower motor neuron syndromes. Selective patterns of reactivity indicate that specific carbohydrate epitopes on the glycolipids are the targets of the high-titer antibodies in individual patients with lower motor neuron syndromes. Several distinct lower motor neuron syndromes can be identified based on clinical, physiological, and antiglycolipid antibody characteristics. These syndromes include multifocal motor neuropathy with evidence of multifocal conduction block on motor, but not sensory, axons and frequent (84%) high titers of anti-GM1 ganglioside antibodies; a lower motor neuron syndrome with predominantly distal weakness early in the disease course, no conduction block, and a high incidence (64%) of anti-GM1 antibodies; and a lower motor neuron syndrome with predominant early weakness in proximal muscles and serum antibodies to asialo-GM1 that do not cross-react with GM1 ganglioside.

The role of thermography in the evaluation of lumbosacral radiculopathy

We studied 27 normal subjects and 30 patients with low back pain to evaluate the diagnostic accuracy of thermography in the diagnosis of lumbosacral radiculopathy. Thermographic abnormality was defined as the presence of either interside temperature difference exceeding 3 standard deviations from the normal mean, or an abnormal heat pattern overlying the lumbosacral spine. In patients with clinically unequivocal radiculopathy, thermography and electrophysiologic study were similar in diagnostic sensitivity, and the 2 methods agreed on the presence or absence of abnormality in 71% of cases. However, the thermographic findings had limited localizing value. Relative limb warming was often seen in patients with acute denervation on EMG, and limb cooling in those with more chronic lesions, but the side of the root lesion could not be identified confidently by thermography alone. Moreover, thermographic abnormalities appeared not to follow a dermatomal distribution and failed to identify the clinical or electrophysiologic level of radiculopathy in most cases. Thus, the thermographic findings are nonspecific, of little diagnostic value, and of uncertain prognostic relevance.

Evaluation of thermography in the diagnosis of selected entrapment neuropathies

We studied 20 normal subjects, 22 patients with carpal tunnel syndrome, and 15 with ulnar neuropathy at the elbow to compare the diagnostic accuracy of infrared thermography with that of conventional electrodiagnostic studies. We found abnormal thermograms in 55% of patients with carpal tunnel syndrome and 47% with ulnar neuropathy, using 2.5 SD from the normal mean as criteria for abnormality. The abnormalities consisted of either an increase in interside temperature difference in the fingers and hands or an alteration of the normal thenar-hypothenar temperature gradient in the fingers. The sensitivity of thermography was considerably lower than that of conventional electrodiagnostic methods. Moreover, the thermographic abnormalities were nonspecific, and could be misleading as they did not reliably identify the side of lesion or distinguish between median or ulnar nerve involvement. Thus, thermography is not helpful in the diagnosis of these two common entrapment neuropathies.

Neuromuscular effects distant from the site of botulinum neurotoxin injection

We assessed the severity and temporal profile of distant neuromuscular effects from a single dose (280 units) of botulinum neurotoxin injected into neck muscles for torticollis. We performed single-fiber EMG studies on the biceps brachii of six patients to measure jitter (20 pairs) and fiber density on the initial treatment day and then again, at least once more, after 2 to 12 weeks. No patient developed weakness beyond the neck muscles or decrement of the biceps response to repetitive 3-Hz nerve stimulation. Between the baseline and the last follow-up study, the average of mean MCD increased from 29 microseconds to 38 microseconds (31%). Mean fiber density increased concurrently or earlier from 1.35 to 1.79 (33%). There were no electrophysiologic signs of presynaptic blockade, even at 2 and 4 weeks. The effects we observed are compatible with stimulation of terminal sprouting by the neurotoxin, without significant presynaptic inhibition of acetylcholine release. We therefore believe that higher dosages of the neurotoxin may be used if clinically indicated.

Peripheral neuropathy associated with acquired immunodeficiency syndrome. Prevalence and clinical features from a population-based survey

We prospectively studied 40 hospitalized patients who had well-established diagnoses of acquired immunodeficiency syndrome. Patients with confounding risk factors for neuropathy were excluded; none of the study patients had known vitamin deficiency, alcoholism, or any metabolic, drug, or toxic factor. Clinical and electrophysiologic evidence of a distal symmetric polyneuropathy was found in 35% (13/37) of the patients. Symptoms and signs of neuropathy were usually mild, and painful dysesthesias were uncommon. Amplitude reduction of sural nerve action potentials distinguished all patients with from those without clinical neuropathy. Results of other electrophysiologic studies of sural, peroneal, and median nerves were typically normal. These results provide evidence of distal axonal degeneration. Neuropathy occurred only in patients with systemic illness longer than five months' duration. When compared with patients without neuropathy, these patients had more severe weight loss and a higher incidence of clinical dementia. Follow-up evaluation showed no evidence of clinical progression over a six-month period. The pathogenesis of this common distal axonal polyneuropathy is unknown and warrants further investigation.

AAEE case report #15: ulnar neuropathy at or distal to the wrist

A 56-year-old woman developed insidiously progressive, painless weakness of her left hand. Clinical and electrodiagnostic abnormalities were limited to the motor function of the hand, with the hypothenar less affected than more distal ulnar muscles. Compression of the distal ulnar nerve by a ganglionic cyst was surgically relieved and there was postoperative improvement. The electrodiagnosis of ulnar neuropathy at or distal to the wrist is reviewed together with relevant anatomic and clinical aspects of these uncommon lesions.