Chronic relapsing brachial plexus neuropathy with persistent conduction block

Idiopathic brachial plexus neuropathy (BPN) is an immune-mediated disorder characterized by an acute onset of painful weakness in one or both upper extremities. The course is usually monophasic with gradual improvement over months; however, occasionally BPN can recur. Electrophysiologic studies suggest the pathogenesis is primarily axonal in the majority of cases. We describe an unusual case of BPN in which the patient had a chronic and relapsing course of painless weakness associated with conduction blocks and other electrophysiologic features of demyelination across the brachial plexus. The patient improved following treatment with intravenous immunoglobulin. The neuropathy falls within the spectrum of chronic inflammatory demyelinating polyneuropathy and multifocal motor neuropathy.     

Long term follow up of multifocal motor neuropathy with conduction block under treatment

OBJECTIVE: To determine the accuracy and potential harmfulness of the drug information in a newsgroup on the Internet, sci.med.pharmacy. DESIGN: In this cross-sectional study, two independent reviewers analyzed the nonsubjective drug information in this newsgroup. Drug information was classified as correct, incorrect or could not verify. Information was determined to have no harm, minor harm, moderate harm, or severe harm. RESULTS: About one-half of the drug information was found to be correct in this newsgroup. Although 68% of the drug information was found to result in no harm, 19.4% was classified as harmful. CONCLUSIONS: If drug information on the Internet contains inaccuracies, its ready accessibility may pose a public health problem. With the number of Internet users growing, health professionals need to be aware of the potential for dissemination of misinformation, and need to become familiar with the Internet and the various health information resources available to the public.     

Lower extremity sensory nerve conduction studies

The need for routine recording of sensory potentials in the lower extremity was developed in efforts to better investigate peripheral neuropathy. Sensory nerve conduction studies (NCS) are more sensitive to many abnormalities in the peripheral nervous system than the motor NCS responses. This article provides a thorough review of sensory nerve conduction studies of the lower extremity, with special emphasis on electrodiagnostic issues.     

Motor and sensory conduction in the musculocutaneous nerve

Motor and sensory conduction velocity in the musculocutaneous nerve were determined in 51 normal subjects. The maximal velocity from the anterior cervical triangle to the axilla was the same in motor and sensory fibres. The conduction velocity decreased 2m/s per 10 years increase of age. It was 70 m/s at 15-24 years and 58 m/s at 65-74 years. The velocity of the slowest components in sensory fibres was 17 m/s. Three selected case reports illustrate the diagnostic value of the method.     

Intermediate nerve conduction velocities define X-linked Charcot-Marie-Tooth neuropathy families

Three genetic loci for the Charcot-Marie-Tooth (CMT) syndromes with slow motor nerve conduction velocities (hereditary motor and sensory neuropathy: HMSN type I) have been mapped to chromosomes 1 (CMT1B), 17 (CMT1A), and the X chromosome (CMTX). The clinical features of these three CMT subgroups are similar. To determine whether any clinical features distinguish CMTX families, the range of clinical findings and motor nerve conduction velocities were examined in two large CMTX families, the range of clinical findings and motor nerve conduction velocities were examined in two large CMTX families with CMTX proven by linkage to X-chromosome markers. CMTX males had more wasting and weakness than CMTX females or individuals with CMT1A. Patellar reflexes were more often retained in CMTX. Motor nerve conduction velocities were faster than in CMT1A. Intermediate-range median nerve conduction velocities were present in CMTX females (45 +/- 9 m/sec; range, 26 to 61 m/sec). These velocities were significantly faster than those for CMT1A females (22 +/- 8 m/sec, p < 0.0001). Median nerve conduction velocities in CMTX males (31 +/- 6 m/sec) were significantly slower than in CMTX females and faster than in CMT1A males (20 +/- 6 m/sec, p < 0.0001). The combination of slow conduction velocities in affected males (< 40 m/sec) and intermediate-range median motor conduction velocity results (> 40 m/sec) in affected or obligate carrier females is a useful distinguishing feature to separate CMTX from CMT1A, as intermediate conduction velocities are not present in autosomal-dominant dominant CMT1A families. This feature defines possible CMTX families for linkage studies. Families with no male-to-male inheritance of the syndrome, slow motor nerve conductions in affected males, and normal or intermediate-range conduction velocities in carrier females should be considered to be X-linked CMT families.     

Suprascapular nerve block for persistent rotator cuff lesions

The suprascapular nerve supplies sensory nerves to the posterosuperior aspect of the shoulder, including major portions of the rotator cuff. Suprascapular nerve block using steroid/bupivacaine is temporarily effective in reducing pain in rotator cuff tendinitis and tears, improving movement range in tendinitis and is possible in an outpatient setting with little or no complication risk.     

Symmetry of normal motor and sensory nerve conduction measurements

Nerve conduction measurements in normal subjects are assumed to be symmetric, but the normal limits of symmetry have not been determined. Full data on the limits of symmetry for commonly studied nerves are important in the clinical interpretation of nerve conduction data. We selected normal electrodiagnostic studies from archived electromyographic laboratory reports that included bilateral measurements of motor and sensory nerves. Symmetry of nerve conduction measures was confirmed, and only the median and ulnar sensory nerves had significant deviations from symmetry, supporting subclinical nerve damage in the most common dominant hand. The limits of symmetry were determined by calculating the 95th percentile for the differences between sides. For motor and sensory nerves, the range of 95th percentile limits was narrower for measures in upper extremity nerves compared to lower extremity nerves. Several reasons are offered for the wider limits of symmetry in lower extremity nerves.     

Rapid improvement of nerve conduction in a patient with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)

A patient with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) underwent electrophysiological examinations before and three days after high-dose intravenous gamma-globulin therapy. In only three days, the distal latency and MCV of the right median nerve were markedly improved without change of amplitude or configuration of CMAP. Such rapid improvement in conduction velocity might not be due to remyelination, because it occurred in only three days. During recovery from conduction block after lidocaine administration in normal subjects, the distal latency was shortened without the change of its amplitude and configuration. This phenomenon is similar to the improvement in the distal latency of the right median nerve of this patient after high-dose intravenous gamma-globulin therapy. We assume, therefore, that the conduction slowing in CIDP should be attributed to inactivation of sodium channels as well as demyelination.     

Inflammatory infiltrates in sural nerve biopsies in Guillain-Barre syndrome and chronic inflammatory demyelinating neuropathy

Prompted by observations in experimental autoimmune neuritis we reanalyzed immunohistochemically the inflammatory infiltrates in sural nerve biopsies of 22 cases with Guillain-Barre syndrome (GBS) and 13 cases with chronic inflammatory demyelinating polyneuropathy (CIDP). Endoneurial infiltration of CD3+ T cells was found in 20 cases of GBS (median 5.5 cells/mm(2)) and in 10 cases of CIDP (5 cells). Epineurial T cells were present in all GBS cases (19.5 cells) and in 11 CIDP cases (21 cells). CD68+ macrophages were abundant in these neuropathies and often occurred in endoneurial perivascular clusters. In GBS subgroups the number of endoneurial T cells was significantly higher in patients with hypoesthesia and abnormal electrophysiological findings in the sural nerve. In CIDP hypoesthesia was associated with significantly higher numbers of macrophages. Our study also indicates that other factors including the time point of biopsy or previous corticosteroid treatment may influence the inflammatory cell profile. Quantifying cell infiltration may aid in establishing the diagnosis of an immunoneuropathy in patients with mild and noncharacteristic pathology.     

Subacute multifocal painful neuropathy with spontaneous remission

We present the cases of two patients with subacute onset of multifocal painful neuropathy with spontaneous remission and no relapse. The distribution of pain in patient 1 was hands (median > ulnar nerve region) and feet (peroneal and terminal tibial nerve regions), and in patient 2, hands (ulnar nerve region) and feet, left worse than in right. Both patients experienced facial numbness. Deep tendon reflexes were intact except for absent ankle jerks in patient 2. Motor nerve conduction studies demonstrated a marked prolongation of the distal motor latencies with normal proximal segment conduction velocities, suggesting distal demyelination. Cerebrospinal fluid protein concentration was elevated in patient 2, but no definite abnormality was found on sural nerve biopsy. A demyelinating neuropathy with a monophasic self-limited course may be consistent with Guillain-Barre syndrome (GBS). However, the multifocal painful sensory symptoms with facial numbness and the marked distal nerve conduction slowing in our cases are not consistent with GBS.     

Methylmercury poisoning, Clinical follow-up and sensory nerve conduction studies

Methylmercury poisoning occurred in four cases after passage of methylmercury through the food chain. The neurological damage in all four cases was severe. The damage was greater at younger ages with maximum involvement in the case of transplacental poisoning. Significant recovery occurred in two cases, but on six-year follow-up two cases remained severely impaired. Clinical and electrophysiological evidence suggests that damage to peripheral sensory nerves may not be the cause of the late sensory symptomatology.     

Electrophysiologic findings in multifocal motor neuropathy

We performed detailed electrophysiologic studies on 16 patients with clinically defined multifocal motor neuropathy and found a wide spectrum of demyelinating features. Only five patients (31%) had conduction block in one or more nerves. However, in 15 patients (94%) at least one nerve showed other features of demyelination. We also noted a significant degree of superimposed axonal degeneration in 15 patients. Eight patients (50%) had individual nerves with pure axonal injury, despite the presence of demyelinating features in other nerves. Antiganglioside antibodies were elevated in four of five patients with conduction block and five of 11 patients without conduction block. We conclude that multifocal motor neuropathy is characterized electrophysiologically by a wide spectrum of axonal and demyelinating features. Diagnostic criteria requiring conduction block may lead to underdiagnosis of this potentially treatable neuropathy.     

Response to therapy in demyelinating motor neuropathy

We reviewed results of immunotherapy in patients with demyelinating motor neuropathy (DMN), and found that patients over 50 years of age at onset responded poorly, and younger patients responded variably to intervention. We suggest that patients with DMN be given a guarded prognosis, particularly if >50 years of age at onset.     

Contralateral early blink reflex in multifocal motor neuropathy

Nurses must share their research and experiences with colleagues in order that areas of practice are debated and improved. Assessing the suitability of a piece of work for a journal and following simple ground rules will increase the likelihood of publication.     

Sensory and mixed nerve conduction studies in the evaluation of ulnar neuropathy at the elbow

The relative sensitivities of sensory, mixed nerve, and motor conduction studies in assessing ulnar neuropathy at the elbow have not yet been established. Using surface electrodes, we performed conduction studies across the elbow segment in 43 patients with symptoms referable to the ulnar nerve and 40 control subjects. Segmental slowing of motor conduction localized the lesion to the elbow in 14 of 21 patients (67%) with clear evidence of ulnar neuropathy on physical examination but only in 2 of 22 (9%) with subtle or no physical examination abnormalities. The diagnostic yield was increased by the finding of segmental slowing of sensory or mixed nerve conduction across the elbow to 86% and 68%, respectively, for each of the groups. We conclude that surface-recorded sensory and mixed nerve conduction studies appear to be more sensitive than motor studies in the electrodiagnosis of ulnar neuropathy at the elbow and are especially valuable in patients with subtle clinical involvement.     

Conduction block in vasculitic neuropathy

Vasculitis involving peripheral nerves usually presents as an acute asymmetrical axonal neuropathy. We report a 67-year-old man with a symmetrical subacute neuropathy in which nerve conduction studies showed prominent conduction block, a finding indicative of demyelination. Sural nerve biopsy showed a vasculitic neuropathy with invasion of blood vessel walls by inflammatory cells and a mixture of nerve fiber loss and demyelination. The demyelination in this case was presumably a consequence of subinfarctive nerve ischemia.     

MRI findings in patients with acute autonomic and sensory neuropathy

Acute autonomic and sensory neuropathy (AASN), characterized by acute onset of extensive autonomic dysfunction and severe sensory deficits, was first described by Colan et al. (1978). We present two female patients with AASN in whom magnetic resonance imaging (MRI) confirmed such findings in the posterior column of the spinal cord. One patient was a 44-year-old woman who developed an upper respiratory tract infection followed in 2 weeks by numbness of the limbs and gait disturbance. There was orthostatic hypotension with syncope, paretic ileus, anhidrosis and urinary retention. There was a loss of sensation over the entire body, including the face, and deep tendon reflexes were generally absent. Neurophysiologic studies showed that sensory nerve action potentials and SSEPs were not evoked in the nerves examined. Sural nerve biopsy demonstrated severe axonal degeneration of the myelinated and unmyelinated fibers. Our second patient, a 27-year-old woman, exhibited similar clinical and laboratory features. The autonomic dysfunction in both patients improved gradually without drug treatment, but the sensory deficits--predominantly a loss of deep sensation--persisted for several years. In both patients, MRI revealed the T2*-weighted high intensity area in the fasciculus gracilis of the posterior column of the spinal cord. Such high intensity areas were present in all spinal segments. The severe and persistent sensory disturbance in these patients may have been caused by a lesion of the posterior column of the spinal cord following the involvement of the dorsal root ganglion cells, or ganglioneuronopathy, as demonstrated by MRI.