Topical capsaicin in painful diabetic neuropathy. Effect on sensory function.

OBJECTIVE: To examine the effect of capsaicin on sensory function in painful diabetic neuropathy. RESEARCH DESIGN AND METHODS: We examined the effects of topical 0.075% capsaicin cream on thermal and vibration thresholds in 22 subjects with painful diabetic neuropathy who participated in a double-blind vehicle-controlled therapeutic trial. RESULTS: After 8 wk of use, there was no significant change in warm and vibration thresholds, but the cold threshold was significantly reduced by capsaicin and vehicle creams to an equal degree. In fewer subjects who used capsaicin cream in an open-label study, there was no significant effect on sensory thresholds after up to 32 wk of use. CONCLUSIONS: Although our results and those of others show no adverse effects of topical 0.075% capsaicin on human sensory function, even in subjects with preexisting neuropathic sensory impairment, the small number of subjects tested does not justify an inferential statement on safety. Further studies in more subjects are warranted to ensure the long-term safety of capsaicin for pain relief in humans.

Topical capsaicin in painful diabetic neuropathy. Controlled study with long-term follow-up.

OBJECTIVE: We conducted an 8-wk controlled study with topical 0.075% capsaicin in subjects with chronic severe painful diabetic neuropathy who were unresponsive or intolerant to conventional therapy. Capsaicin is an alkaloid found in capsicum peppers and produces desensitization to noxious thermal, chemical, and mechanical stimuli when applied topically. RESEARCH DESIGN AND METHODS: In 22 randomly assigned subjects, either capsaicin or vehicle cream was applied to painful areas 4 times/day. Pain measurements were recorded at baseline and at 2-wk intervals for 8 wk. RESULTS: Capsaicin treatment was more beneficial than vehicle treatment in the overall clinical improvement of pain status, as measured by physician's global evaluation (P = 0.038) and by a categorical pain severity scale (P = 0.057). Decrease in mean pain intensity by a visual analogue scale was 16% in capsaicin-treated and 4.1% in vehicle-treated subjects. Mean pain relief on visual analogue scale was 44.6 and 23.2%, respectively. In a follow-up open-label study, approximately 50% of subjects reported improved pain control or were cured, and 25% each were unchanged or worse. A burning sensation at the application site was noted by some subjects but both its magnitude and duration decreased with time. CONCLUSIONS: Results from this preliminary study suggest that topical 0.075% capsaicin may be of value in subjects with diabetic neuropathy and intractable pain.

Chronic inflammatory demyelinating polyradiculoneuropathy: a study of proposed electrodiagnostic and histologic criteria.

OBJECTIVE: To examine the sensitivity of the 3 proposed electrodiagnostic (EDX) criteria for demyelination, the sensitivity and specificity of the proposed Ad Hoc Subcommittee of the American Academy of Neurology AIDS [Acquired Immunodeficiency Syndrome] Task Force histologic criteria (AAN criteria), the degree of agreement among these criteria, and the diagnostic value of sural nerve histologic criteria in patients with idiopathic chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). DESIGN AND METHODS: A retrospective analysis of 24 patients with idiopathic CIDP and 12 patients with diabetic polyneuropathy (DP) who underwent comparable testing of clinical, histologic, and EDX features. RESULTS: We found 42%, 50%, and 79% sensitivity of the proposed EDX, AAN teased fiber, and AAN electron microscopic (EM) criteria, respectively, for demyelination in CIDP. The specificity of the proposed AAN teased fiber and EM criteria for demyelination was greater than 80% when tested against patients with DP. There was lack of agreement between the EDX and histologic criteria. Almost two thirds of patients with CIDP who met the EM criteria but none of the EDX criteria for demyelination showed a favorable response to immunomodulatory therapy. CONCLUSIONS: Sural nerve histologic criteria offer unique sensitivity and acceptable specificity toward the diagnosis of CIDP. Sural nerve biopsy should be considered when a clinical suspicion of CIDP remains in patients who do not meet the proposed EDX criteria for demyelination.

Myelomalacia and hypoglycorrhachia in malignant atrophic papulosis.

A 25-year-old man with the skin lesions of malignant atrophic papulosis had clinical and electrodiagnostic evidence of a multifocal asymmetric myelomalacia or polyradiculopathy in association with elevated CSF protein and hypoglycorrhachia. Autopsy findings included widespread infarctions and necrosis of brain, brainstem, and spinal cord. The combined clinical and laboratory findings were similar to those seen in systemic lupus erythematosus, sarcoidosis, or meningeal carcinomatosis. Thus, malignant atrophic papulosis should be added to the differential diagnosis of either polyradiculopathy or myelomalacia.

Respiratory muscle involvement in Bethlem myopathy.

We report a patient from a previously reported family with autosomal dominant Bethlem myopathy who demonstrated childhood onset, slowly progressive limb-girdle muscle weakness, contractures, and progressive respiratory compromise. Chest x-ray, pulmonary function tests, and electrophysiologic studies suggested respiratory muscle involvement, thus expanding the clinical repertoire in Bethlem myopathy.

Chronic segmental spinal muscular atrophy of upper extremities in identical twins.

We present the 1st report of chronic segmental spinal muscular atrophy confined to the upper extremities in identical male twins. This occurrence in identical twins, together with reports of siblings and parent-child pairs of a disorder phenotypically similar to the more common sporadic form in the literature, suggests a genetic etiology in some cases.

Benign autosomal dominant syndrome of neuronal Charcot-Marie-Tooth disease, ptosis, parkinsonism, and dementia.

We present a kindred with a previously undescribed combination of neuronal Charcot-Marie-Tooth disease, ptosis, parkinsonism, and mild dementia. The propositus, a 72-year-old man, had pes cavus, peripheral neuropathy, ptosis, parkinsonism, hyperreflexia, orthostatic hypotension, central hypoventilation, and mild dementia. Peripheral electrophysiologic studies showed features of an axonal neuropathy. The electroencephalogram showed intermittent 2 to 4 Hz activity symmetrically in the hemispheres. Several family members in 3 generations had pes cavus, neuropathy, ptosis, parkinsonism, and dementia although not all of the features were consistently present. Survival past the 7th decade was common. Autopsy in 2 affected members revealed the neuropathy to be axonal in type and showed mild to moderate loss of anterior horn cells in the spinal cord and pigmentary loss with gliosis in the substantia nigra. This is a unique, benign, autosomal dominant syndrome which shows complete penetrance, variable expression, and both central and peripheral nervous system involvement.

Early-onset benign autosomal dominant limb-girdle myopathy with contractures (Bethlem myopathy).

We report a large French-Canadian kindred with 33 affected members in six generations showing early-onset autosomal dominant limb-girdle myopathy and contractures. This myopathy is unique because of its benign course, with many members only minimally impaired even in old age. Examination of affected members revealed mild to moderate proximal weakness and wasting. Contractures were observed at the elbows and ankles in all, while in some they were more widespread. Serum CK was either normal or slightly raised, and electrodiagnostic studies suggested a primary myopathy. Muscle biopsy revealed nonspecific features of a myopathy without fiber necrosis or regeneration. Cardiac involvement was absent clinically in all patients and at autopsy in two affected individuals. The similarities between four previously reported families and our own establishes this myopathy as a distinct clinicogenetic entity, for which we propose the name "Bethlem myopathy."

A controlled trial of amino acid therapy in amyotrophic lateral sclerosis: I. Clinical, functional, and maximum isometric torque data.

We conducted a two center, double-blind, placebo-controlled treatment trial with oral branched chain amino acids (BCAA) (L-leucine 12 g, L-isoleucine 8 g, and L-valine 6.4 g daily) or L-threonine (4 g daily) with pyridoxal phosphate (160 mg daily) for six months in patients with amyotrophic lateral sclerosis (ALS). The effect of treatment on disease progression was estimated every two months by recording clinical muscle strength, maximum isometric muscle torque in selected muscles, forced vital capacity (FVC), activities of daily living pertaining to the upper and lower limbs, and timed tasks. Ninety-five patients were randomized to receive BCAA (n = 31), L-threonine (n = 32), or placebo (n = 32), of whom 77 (81%) completed the trial. Mean weight loss in the placebo group was 1.1 kg and in the L-threonine group was 3.2 kg; the BCAA group gained 0.2 kg (p = 0.04). The estimated decline in FVC was about 2.5 times greater in the BCAA and L-threonine groups as compared to placebo (p = 0.03). Otherwise, no significant differences were found in the changes observed in clinical, functional, timed, or maximum torque measures among treatment groups. The amino acids were well tolerated. The results of our study failed to show a beneficial effect of BCAA or L-threonine treatment for six months on the disease course in ALS. The higher rate of loss of pulmonary function in patients treated with BCAA or L-threonine may have been due to chance, but an adverse effect of these amino acids cannot be ruled out.

Double-blind controlled trials of Cronassial in chronic neuromuscular diseases and ataxia.

We report three 12-month, double-blind, three-phase studies comparing the effect of placebo and 40 mg and 100 mg IM daily of purified bovine brain gangliosides (Cronassial) in chronic neuromuscular diseases. Thirty patients with Charcot-Marie-Tooth disease, 16 with idiopathic polyneuropathy, and 30 with spinocerebellar degeneration had neuromuscular function measured monthly by quantitative testing of motor and sensory function, coordination, and electrophysiologic factors. Analysis of these studies, and of longer term (up to 2 years) open studies of 100 mg daily of Cronassial in 67 patients failed to show therapeutic efficacy of Cronassial. Statistical power calculations indicated that five of the 37 measures had greater than a 70% chance of detecting a 20% difference in the rate of progression of the active-drug and placebo groups. A number of measures significantly improved during prolonged placebo treatment, suggesting that the placebo effect has a strong influence on "objective" measures of neuromuscular function.

A multicenter, randomized, double-blinded trial of pyridostigmine in postpolio syndrome.

BACKGROUND: Postpoliomyelitis syndrome (PPS) is likely due to degeneration and dysfunction of terminal axons of enlarged postpolio motor units. Age-related decline in growth hormone and insulin-like growth factor (IGF-I) may be a contributing factor. Neuromuscular junction abnormalities and decreased IGF-I levels may respond to the anticholinesterase pyridostigmine, with consequent improvement in strength, fatigue, and quality of life. OBJECTIVES: To determine the effect of pyridostigmine in PPS on health-related quality of life, isometric muscle strength, fatigue, and serum IGF-I levels; and to assess the safety of pyridostigmine in PPS. METHODS: The study was a multicenter, randomized, double-blinded, placebo-controlled trial of a 6-month course of pyridostigmine 60 mg three times per day in 126 PPS patients. The primary data analysis compared mean changes of outcomes between treatment and control groups at 6 months using an intention to treat approach. Secondary analyses included a comparison of outcomes at 6 and 10 weeks, and in compliant patients. RESULTS: The study showed no significant differences in pyridostigmine and placebo-treated patients with regard to changes in quality of life, isometric strength, fatigue, and IGF-I serum levels at 6 months in the primary analysis and in compliant patients. There were no differences in outcomes at 6 and 10 weeks between groups. However, very weak muscles (1 to 25% predicted normal at baseline) were somewhat stronger (p = 0.10, 95% CI of difference -9.5 to 73.3%), and in compliant patients IGF-I was somewhat increased (p = 0.15, 95% CI of difference -6.4 to 44.8 ng/mL) at 6 months with the medication. Pyridostigmine was generally well tolerated. CONCLUSIONS: This study showed no significant differences between pyridostigmine and placebo-treated PPS patients on measures of quality of life, isometric strength, fatigue, and serum IGF-I.

Novel mutations in spastin gene and absence of correlation with age at onset of symptoms.

Autosomal dominant hereditary spastic paraplegia is genetically heterogeneous, with at least five loci identified by linkage analysis. Recently, mutations in spastin were identified in SPG4, the most common locus for dominant hereditary spastic paraplegia that was previously mapped to chromosome 2p22. We identified five novel mutations in the spastin gene in five families with SPG4 mutations from North America and Tunisia and showed the absence of correlation between the predicted mutant spastin protein and age at onset of symptoms.

Randomized controlled trial of IVIg in untreated chronic inflammatory demyelinating polyradiculoneuropathy.

OBJECTIVE: To determine the efficacy of IV immunoglobulin (IVIg) given patients with untreated chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). METHODS: A randomized, double-blind, multicenter, investigator-initiated study compared IVIg (Aventis Behring LLC, King of Prussia, PA) with placebo (5% albumin). On days 1, 2, and 21, IVIg (1 g/kg) or placebo was given. The primary outcome measure was the change in muscle strength from baseline to day 42, using the average muscle score (AMS). Secondary outcome measures included change from baseline AMS at days 10 and 21, the Hughes' functional disability scale, forced vital capacity (FVC), and nerve conduction studies (NCS) of four motor nerves (median, ulnar, peroneal, and tibial). RESULTS: The patients (n = 33) were randomized. Of these, 30 (14 women, 16 men, aged 54 +/- 20 years, range 13 to 82) received IVIg and 23 were given placebo (12 women, 11 men, aged 50 +/- 18 years, range 23 to 73). Baseline AMS values of the groups were similar (IVIg 7.06 +/- 1.31 versus placebo 7.28 +/- 1.18, p = 0.53). There were two dropouts in placebo group and one in the IVIg group. Mean AMS improved at day 42 comparing IVIg with placebo (0.63 versus -0.1, p = 0.006). Improved strength was seen by day 10. The placebo group lost strength over this same interval. In the IVIg, 11 subjects improved by the functional disability scale; none worsened. This differed (p = 0.019) from those in the placebo-treated group (two improved, two got worse, remainder unchanged). Forced vital capacity did not improve with IVIg treatment. IVIg improved ulnar motor distal latency (p = 0.005), tibial distal compound muscle amplitude (p = 0.003), and peroneal nerve conduction velocity (p = 0.03). CONCLUSIONS: IVIg improves strength in patients with untreated CIDP by day 10 with continued benefit through day 42; more than one third improve by at least a functional grade on a disability scale. This study provides data supporting IVIg as the initial treatment for CIDP.

Adult-onset autosomal recessive neurogenic scapuloperoneal syndrome.

We report a brother and sister who showed weakness, atrophy and fasciculations starting in adulthood, predominantly affecting the muscles of the shoulder girdles and distal lower extremities. Mild ptosis and facial weakness were present in both. Electrophysiological studies and muscle histology supported a neurogenic basis for the autosomal recessive scapuloperoneal syndrome in this sibship.

Repair of N-methylpurines in DNA from lymphocytes of patients with amyotrophic lateral sclerosis.

We have previously reported reduced ability of ALS fibroblasts to repair genomic DNA damage produced by alkylating agents. This report presents our experience of studying DNA repair in lymphocytes from ALS patients. The repair of N-methylpurines produced by treatment with the alkylating agent, methyl methanesulfonate, was studied in T-lymphocytes from patients with sporadic and familial ALS, and appropriate controls. Repair of damage was quantitated by using alkaline elution for genomic DNA repair, and methoxyamine protection of abasic sites in DNA fragments for gene-specific repair in the dihydrofolate reductase (dhfr) gene, at time points 0, 6 h and 24 h. No significant repair rate differences were observed between ALS and control lymphocytes in either genomic or gene-specific DNA repair. The possible reasons for the discrepancy with our earlier results in lymphocytes and fibroblasts are discussed.

Giant axonal neuropathy: studies with sulfhydryl donor compounds.

Giant axonal neuropathy (GAN) is a disorder characterized pathologically by distal neurofilament-filled bulbous swellings in axons, and widespread collection of intermediate filaments, including masses of vimentin filaments in cultured skin fibroblasts. A morphologically similar neurofibrillary disorder is produced by acrylamide and the toxic hexacarbons, agents which bind to thiol groups. We report, in GAN fibroblasts, inhibition of vimentin filament aggregation by dithiothreitol and penicillamine, sulfhydryl donor compounds which stabilize thiols. In addition, we describe clinical improvement in a GAN patient treated with penicillamine, despite earlier progressive disease. These findings support the hypothesis of disordered thiol metabolism in GAN, and open up avenues for further research.

Deficient DNA repair in amyotrophic lateral sclerosis cells.

We studied survival and DNA repair capacity in cultured sporadic ALS and control skin fibroblasts after treatment with DNA damaging agents producing different types of lesions. Mean survival in ALS and control fibroblasts was similar after exposure to ultraviolet (UV) light, x-rays and mitomycin C (MMC). Both mean survival and mean unscheduled (repair) DNA synthesis (UDS) were significantly reduced in ALS fibroblasts following treatment with the alkylating agent methyl methane sulfonate (MMS). These data suggest that ALS cells are relatively deficient in the repair of alkylation damage, possibly of apurinic/apyrimidinic sites, and that they are not unduly sensitive to DNA damage produced by UV light, x-rays and MMC. Normal survival and UDS seen in some patients' cells after MMS treatment indicate a spectrum of repair efficiency, and suggest heterogeneity of the biochemical defect in ALS.

Electrophysiologic endpoint measures in a multicenter ALS drug trial.

We report the analysis of a battery of secondary electrophysiologic measurements to assess the progression of amyotrophic lateral sclerosis (ALS) in a two center, six month, double-blind, three arm trial comparing branched chain amino acids to L-threonine with pyridoxal 5-phosphate to placebo. The endpoint measurements were chosen to separately assess the effects of lower motor neuron loss and collateral reinnervation. For tests of inter-center reliability, we found no differences that could not be readily explained by variations in electrophysiologic testing techniques. Since the drug study was negative for the primary endpoint measure (muscle strength), we combined data from both centers and the three treatment arms. For measures of progression, all measures changed in the expected direction during the 6 months of the trial. We conclude that a battery of electrophysiologic measures can be used in a multicenter ALS drug trial to provide information on changes in lower motor neuron numbers and the effects of collateral reinnervation.

Childhood giant axonal neuropathy. Case report and review of the literature.

Giant axonal neuropathy (GAN) is a rare autosomal recessive childhood disorder characterized by a peripheral neuropathy and features of central nervous system involvement. Typically seen are distal axonal swellings filled with 8-10 nm in diameter neurofilaments in central and peripheral axons, and intermediate filament collections in several other cell types. Many neurotoxins produce a morphologically similar neuropathy in humans and experimental animals. Defective nerve fiber energy metabolism has been postulated as a cause in these toxic neuropathies. It is possible that GAN represents an inborn error of metabolism of enzyme-linked sulfhydryl containing proteins, resulting in impaired production of energy necessary for the normal organization of intermediate filaments.

Quantitative measures of neurological function in chronic neuromuscular diseases and ataxia.

Interexaminer and intraexaminer reliability were determined for 30 quantitative measures of neurological function, including sensory threshold, tendon reflexes, maximum isometric strength, and timed tests and coded ratings of functional ability, in patients with Charcot-Marie-Tooth disease (n = 30), idiopathic polyneuropathy (n = 16) and spinocerebellar degeneration (n = 30). Five of 6 sensory and reflex measures had interexaminer reliability greater than 0.80 when the neurologists' examinations were 1 h apart; 2 of 7 achieved this level when the examinations were separated by 1 month. Interexaminer reliability between physical therapists was greater than 0.80 for 19 of 20 measures of strength and functional ability. Intraexaminer reliability coefficients greater than 0.80 were found for 13 of 24 sensory and reflex measures, 28 of 30 isometric strength measures, 24 of 30 timed tests and 5 of 6 coded ratings of functional ability. Electro-oculography, oral diadochokinetic syllable rates, hand and foot accelerometry, and tracings of sine and square waves were examined as quantitative indices of ataxia for patients with spinocerebellar degeneration. Of 11 measures of ataxia, only the oral diadochokinetic syllable rate test had acceptable reliability.