Motor neuropathies mimicking amyotrophic lateral sclerosis/motor neuron disease

Electrodiagnostic profile of conduction slowing in amyotrophic lateral sclerosis

Objective

Since motor nerve conduction slowing can occur due to loss of large axons, we investigate the conduction slowing profile in amyotrophic lateral sclerosis (ALS) and identify the limits beyond which the diagnosis of exclusive axonal loss is unlikely.

Methods

First, using linear regression analysis, we established the range of motor conduction slowing in 76 chronic inflammatory demyelinating polyneuropathy (CIDP) patients. Demyelinating range confidence intervals were defined by assessing conduction velocity (CV), distal latency (DML), and F-wave latency (F) in relation to distal compound muscle action potential (CMAP) amplitude of median, ulnar, fibular, and tibial nerves. Results were subsequently validated in 38 additional CIDP patients. Then, the newly established demyelination confidence intervals were used to investigate the profile of conduction slowing in 95 ALS patients.

Results

CV slowing, prolonged DML, and abnormal F were observed in 22.2%, 19.6%, and 47.1% of the studied nerves respectively in ALS patients. When slowing occurred, it affected more than one segment of the motor nerve, suggesting that CMAP amplitude dependent conduction slowing caused by an exclusive loss of large axons is the main mechanism of slowing. No ALS patient had more than 2 nerves with CV slowing in the confidence interval defined by the regression equations or the American Academy of Neurology (AAN) research criteria for CIDP diagnosis.

Conclusions

The presence of more than two motor nerves with CV slowing in the demyelinating range defined by the regression analysis or AAN criteria in ALS patients suggests the contribution of acquired demyelination or other additional mechanisms exist in the electrodiagnostic profile of ALS.

Prolonged distal latency of the median motor nerve is associated with poor prognosis in amyotrophic lateral sclerosis

A nerve conduction study (NCS) is routinely undertaken for the differential diagnosis of amyotrophic lateral sclerosis (ALS). Prolonged median motor distal latency (MMDL) has been reported in a subset of patients with ALS. This study aimed to investigate the clinical importance of NCS characteristics in patients with ALS. A total of 75 patients who underwent NCS were enrolled in this study. The frequency of ALS patients with prolonged motor DL was higher in the median than ulnar NCS. The multivariate analysis revealed that shorter diagnostic latency, prolonged MMDL, and higher disease progression rate were significantly associated with poor prognosis. When ALS patients were divided into two groups according to the cut-off value (4.2 ms) of the MMDL, the group with prolonged MMDL had lower ALS functional rating scale and frontal assessment battery scores, upper limbs subscore, and shorter survival time than the group with shorter MMDL. In conclusion, patients with ALS that have prolonged MMDL may have upper limb dysfunction and shorter survival. MMDL can be a useful prognostic marker for patients with ALS. Abbreviations: ADM = abductor digiti minimi; APB = abductor pollicis brevis; ALS = amyotrophic lateral sclerosis; ALSFRS-R = revised ALS Functional Rating Scale; CI = confidence interval; CMAP = compound muscle action potential; CTS = carpal tunnel syndrome; DL = distal latency; ΔFS = disease progression rate; FAB = frontal assessment battery; FVC = forced vital capacity; HR = hazard ratio; MCV = motor nerve conduction velocity; MMDL = median motor distal latency; MMSE = mini-mental state examination; NCS = nerve conduction study; PaCO₂ = partial pressure of arterial carbon dioxide; SBMA = spinal and bulbar muscular atrophy; SCV = sensory nerve conduction velocity; SD = standard deviation; SMA = spinal muscular atrophy; SNAP = sensory nerve action potential; SOD1 = superoxide dismutase 1; UMDL = ulnar motor distal latency.

Correlation between distal motor latency and compound muscle action potential in amyotrophic lateral sclerosis

OBJECTIVES

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder, characterized by a selective progressive degeneration of the motor system. Electromyography is essential for the diagnosis of ALS. The measurement of motor conduction of peripheral nerves is of major importance to recognize other possible causes of progressive muscle wasting. However, there are also pathologic changes in nerve conduction studies in ALS patients.

METHODS

In this study we analysed the values of distal motor latency (DML), compound muscle action potential (CMAP) and motor nerve conduction velocity (MNCV) in 95 patients with definite ALS.

RESULTS

We found slight slowing of MNCV and moderate to strong reduction of CMAP and a prolongation of DML. We found no significant correlation between MNCV and CMAP.

DISCUSSION

The main finding of the present work was the negative correlation between DML and CMAP. It is interpreted as a very distal axonal damage as the main reason for prolongation of DML in ALS patients.

EFNS guidelines on the clinical management of amyotrophic lateral sclerosis (MALS)--revised report of an EFNS task force

BACKGROUND

The evidence base for the diagnosis and management of amyotrophic lateral sclerosis (ALS) is weak.

OBJECTIVES

To provide evidence-based or expert recommendations for the diagnosis and management of ALS based on a literature search and the consensus of an expert panel.

METHODS

All available medical reference systems were searched, and original papers, meta-analyses, review papers, book chapters and guidelines recommendations were reviewed. The final literature search was performed in February 2011. Recommendations were reached by consensus.

RECOMMENDATIONS

Patients with symptoms suggestive of ALS should be assessed as soon as possible by an experienced neurologist. Early diagnosis should be pursued, and investigations, including neurophysiology, performed with a high priority. The patient should be informed of the diagnosis by a consultant with a good knowledge of the patient and the disease. Following diagnosis, the patient and relatives/carers should receive regular support from a multidisciplinary care team. Medication with riluzole should be initiated as early as possible. Control of symptoms such as sialorrhoea, thick mucus, emotional lability, cramps, spasticity and pain should be attempted. Percutaneous endoscopic gastrostomy feeding improves nutrition and quality of life, and gastrostomy tubes should be placed before respiratory insufficiency develops. Non-invasive positive-pressure ventilation also improves survival and quality of life. Maintaining the patient's ability to communicate is essential. During the entire course of the disease, every effort should be made to maintain patient autonomy. Advance directives for palliative end-of-life care should be discussed early with the patient and carers, respecting the patient's social and cultural background.

Good practice in the management of amyotrophic lateral sclerosis: clinical guidelines. An evidence-based review with good practice points. EALSC Working Group

The evidence base for diagnosis and management of ALS is still weak, and curative therapy is lacking. Nonetheless, early diagnosis and symptomatic therapy can profoundly influence care and quality of life of the patient and relatives, and may increase survival time. This review addresses the current optimal clinical approach to ALS. The literature search is complete to December 2006. Where there was lack of evidence but consensus was clear we have stated our opinion as good practice points. We conclude that a diagnosis of ALS can be achieved by early examination by an experienced neurologist. The patient should be informed of the diagnosis by the consultant. Following diagnosis, a multi-diciplinary care team should support the patient and relatives. Medication with riluzole should be initiated as early as possible. PEG is associated with improved nutrition and should be inserted early. The operation is hazardous in patients with VC <50%: RIG may be a better alternative. Non-invasive positive pressure ventilation improves survival and quality of life but is underused in Europe. Maintaining the patient's ability to communicate is essential. During the course of the disease, every effort should be made to maintain patient autonomy. Advance directives for palliative end of life care are important and should be discussed early with the patient and relatives if they so wish.

Bilateral hand amyotrophy with PMP-22 gene deletion

Hereditary neuropathy with liability to pressure palsies (HNPP) phenotypes are heterogeneous. We report the case of a 52-year-old woman without medical history, who complained of bilateral hand weakness suggestive first of a motor neuron disorder. The presence of a diffuse predominant distal demyelinating neuropathy suggested a deletion of PMP-22 gene, which was confirmed by genetic analysis. This case report underlines a novel phenotype related to the deletion of PMP-22 gene.

EFNS task force on management of amyotrophic lateral sclerosis: guidelines for diagnosing and clinical care of patients and relatives. An evidence-based review with good practice points

Despite being one of the most devastating diseases known, there is little evidence for diagnosing and managing patients with amyotrophic lateral sclerosis (ALS). Although specific therapy is lacking, correct early diagnosis and introduction of symptomatic and specific therapy can have a profound influence on the care and quality of life of the patient and may increase survival time. This document addresses the optimal clinical approach to ALS. The final literature search was performed in the spring of 2005. Consensus recommendations are given graded according to the EFNS guidance regulations. Where there was lack of evidence but consensus was clear we have stated our opinion as good practice points. People affected with possible ALS should be examined as soon as possible by an experienced neurologist. Early diagnosis should be pursued and a number of investigations should be performed with high priority. The patient should be informed of the diagnosis by a consultant with a good knowledge of the patient and the disease. Following diagnosis, the patient and relatives should receive regular support from a multidisciplinary care team. Medication with riluzole should be initiated as early as possible. PEG is associated with improved nutrition and should be inserted early. The operation is hazardous in patients with vital capacity < 50%. Non-invasive positive pressure ventilation improves survival and quality of life but is underused. Maintaining the patients ability to communicate is essential. During the entire course of the disease, every effort should be made to maintain patient autonomy. Advance directives for palliative end of life care are important and should be fully discussed early with the patient and relatives respecting the patients social and cultural background.

Intravenous immunoglobulin for multifocal motor neuropathy

BACKGROUND

Multifocal motor neuropathy is a rare, probably immune mediated disorder characterised by slowly progressive, asymmetric, distal weakness of one or more limbs with no objective loss of sensation. It may cause prolonged periods of disability. The treatment options for multifocal motor neuropathy are sparse. Patients with multifocal motor neuropathy do not usually respond to steroids or plasma exchange, and may even worsen with these treatments. Many uncontrolled studies have suggested a beneficial effect of intravenous immunoglobulin.

OBJECTIVES

To review systematically the evidence from randomised controlled trials concerning the efficacy and safety of intravenous immunoglobulin in multifocal motor neuropathy.

SEARCH STRATEGY

We used the search strategy of the Cochrane Neuromuscular Disease Review Group to search the Disease Group register (searched September 2003), MEDLINE (January 1990 to September 2003), EMBASE (January 1990 to September 2003) and ISI (January 1990 to September 2003) databases for randomised controlled trials.

SELECTION CRITERIA

Randomised controlled studies examining the effects of any dose of intravenous immunoglobulin versus placebo in patients with definite or probable multifocal motor neuropathy. Outcome measures had to include one of the following: disability, strength, or conduction block. Studies which reported the frequency of adverse effects were used to assess safety.

DATA COLLECTION AND ANALYSIS

Two authors reviewed literature searches to identify potentially relevant trials, scored their quality and extracted data independently. For dichotomous data, we calculated relative risks, and for continuous data, effect sizes and weighted pooled effect sizes. Statistical uncertainty was expressed with 95% confidence intervals.

MAIN RESULTS

Four randomised controlled trials including a total of 34 patients were suitable for this systematic review. Strength improved in 78% of patients treated with intravenous immunoglobulin and only 4% of placebo-treated patients. Disability improved in 39% of patients after intravenous immunoglobulin treatment and in 11% after placebo (statistically not significantly different). Mild, transient side effects were reported in 71% of intravenous immunoglobulin treated patients. Serious side effects were not encountered.

AUTHORS' CONCLUSIONS

Limited evidence from randomised controlled trials shows that intravenous immunoglobulin has a beneficial effect on strength. There was a non-significant trend towards improvement in disability. More research is needed to discover whether intravenous immunoglobulin improves disability and is cost-effective.

Rapid Progression of Amyotrophic Lateral Sclerosis Presenting During Pregnancy: A Case Report

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a progressive neurologic disease that is rare within the obstetric population. Only 5 reports of ALS in pregnancy have appeared in the medical literature since 1977.

CASE

A previously healthy 25-year-old pregnant woman with 2 previous births presented with generalized weakness at 22 weeks' gestation. Initial laboratory values were all normal. She was admitted to hospital at 29 weeks' gestation and intubated because of respiratory compromise. Daily biophysical profiles and amniotic fluid indices were normal. Labour was induced at 34.5 weeks' gestation, and delivery was uncomplicated. She died at 9 months postpartum.

CONCLUSION

Pregnancy complicated by the onset of ALS is a rare event. Complications of this disease mainly affect the respiratory system. Death in this case occurred more rapidly than in other previously reported cases.

Electrodiagnostic studies in amyotrophic lateral sclerosis and other motor neuron disorders

The clinical electrodiagnostic medicine (EDX) consultant asked to assess patients with suspected amyotrophic lateral sclerosis (ALS) has a number of responsibilities. Among the most important is to provide a clinical assessment in conjunction with the EDX study. The seriousness of the diagnoses and their enormous personal and economic impact require a high-quality EDX study based on a thorough knowledge of and experience with motor neuron diseases (MNDs) and related disorders. Clinical evaluation will help determine which of the EDX tools available to the EDX consultant should be applied in individual patients. Although electromyography (EMG) and nerve conduction study are the most valuable, each of the following may be helpful in the assessment of selected patients based on their clinical findings: repetitive nerve stimulation, motor unit number estimate, single-fiber EMG, somatosensory evoked potential, autonomic function test, and polysomnography. The pertinent literature on these is reviewed in this monograph. The selection and application of these EDX tools depend on a thorough knowledge of the MNDs and related disorders.