Second consensus statement on the diagnosis of multiple system atrophy

BACKGROUND

A consensus conference on multiple system atrophy (MSA) in 1998 established criteria for diagnosis that have been accepted widely. Since then, clinical, laboratory, neuropathologic, and imaging studies have advanced the field, requiring a fresh evaluation of diagnostic criteria. We held a second consensus conference in 2007 and present the results here.

METHODS

Experts in the clinical, neuropathologic, and imaging aspects of MSA were invited to participate in a 2-day consensus conference. Participants were divided into five groups, consisting of specialists in the parkinsonian, cerebellar, autonomic, neuropathologic, and imaging aspects of the disorder. Each group independently wrote diagnostic criteria for its area of expertise in advance of the meeting. These criteria were discussed and reconciled during the meeting using consensus methodology.

RESULTS

The new criteria retain the diagnostic categories of MSA with predominant parkinsonism and MSA with predominant cerebellar ataxia to designate the predominant motor features and also retain the designations of definite, probable, and possible MSA. Definite MSA requires neuropathologic demonstration of CNS alpha-synuclein-positive glial cytoplasmic inclusions with neurodegenerative changes in striatonigral or olivopontocerebellar structures. Probable MSA requires a sporadic, progressive adult-onset disorder including rigorously defined autonomic failure and poorly levodopa-responsive parkinsonism or cerebellar ataxia. Possible MSA requires a sporadic, progressive adult-onset disease including parkinsonism or cerebellar ataxia and at least one feature suggesting autonomic dysfunction plus one other feature that may be a clinical or a neuroimaging abnormality.

CONCLUSIONS

These new criteria have simplified the previous criteria, have incorporated current knowledge, and are expected to enhance future assessments of the disease.

Consensus statement on the diagnosis of multiple system atrophy

We report the results of a consensus conference on the diagnosis of multiple system atrophy (MSA). We describe the clinical features of the disease, which include four domains: autonomic failure/urinary dysfunction, parkinsonism and cerebellar ataxia, and corticospinal dysfunction. We set criteria to define the relative importance of these features. The diagnosis of possible MSA requires one criterion plus two features from separate other domains. The diagnosis of probable MSA requires the criterion for autonomic failure/urinary dysfunction plus poorly levodopa responsive parkinsonism or cerebellar ataxia. The diagnosis of definite MSA requires pathological confirmation.

Distal symmetric polyneuropathy: a definition for clinical research: report of the American Academy of Neurology, the American Association of Electrodiagnostic Medicine, and the American Academy of Physical Medicine and Rehabilitation

The objective of this report was to develop a case definition of distal symmetric polyneuropathy to standardize and facilitate clinical research and epidemiologic studies. A formalized consensus process was employed to reach agreement after a systematic review and classification of evidence from the literature. The literature indicates that symptoms alone have relatively poor diagnostic accuracy in predicting the presence of polyneuropathy; signs are better predictors of polyneuropathy than symptoms; and single abnormalities on examination are less sensitive than multiple abnormalities in predicting the presence of polyneuropathy. The combination of neuropathic symptoms, signs, and electrodiagnostic findings provides the most accurate diagnosis of distal symmetric polyneuropathy. A set of case definitions was rank ordered by likelihood of disease. The highest likelihood of polyneuropathy (useful for clinical trials) occurs with a combination of multiple symptoms, multiple signs, and abnormal electrodiagnostic studies. A modest likelihood of polyneuropathy (useful for field or epidemiologic studies) occurs with a combination of multiple symptoms and multiple signs when the results of electrodiagnostic studies are not available. A lower likelihood of polyneuropathy occurs when electrodiagnostic studies and signs are discordant. For research purposes, the best approach to defining distal symmetric polyneuropathy is a set of case definitions rank ordered by estimated likelihood of disease. The inclusion of this formalized case definition in clinical and epidemiologic research studies will ensure greater consistency of case selection.

Autoantibodies to ganglionic acetylcholine receptors in autoimmune autonomic neuropathies

BACKGROUND

Idiopathic autonomic neuropathy is a severe, subacute disorder with a presumed autoimmune basis. It is indistinguishable from the subacute autonomic neuropathy that may accompany lung cancer or other tumors. Autoantibodies specific for nicotinic acetylcholine receptors in the autonomic ganglia are potentially pathogenic and may serve as serologic markers of various forms of autoimmune autonomic neuropathy.

METHODS

We tested serum from 157 patients with a variety of types of dysautonomia. Immunoprecipitation assays with iodine-125-labeled epibatidine and solubilized human neuroblastoma acetylcholine receptors were used to detect autoantibodies that bound to or blocked ganglionic receptors.

RESULTS

Ganglionic-receptor-binding antibodies were found in 19 of 46 patients with idiopathic or paraneoplastic autonomic neuropathy (41 percent), in 6 of 67 patients with postural tachycardia syndrome, idiopathic gastrointestinal dysmotility, or diabetic autonomic neuropathy (9 percent), and in none of 44 patients with other autonomic disorders. High levels of the binding antibodies correlated with more severe autonomic dysfunction (including the presence of tonic pupils). Levels of these antibodies decreased in patients who had clinical improvement. All seven patients with ganglionic-receptor-blocking antibodies had ganglionic-receptor-binding antibodies and had idiopathic or paraneoplastic autonomic neuropathy.

CONCLUSIONS

Seropositivity for antibodies that bind to or block ganglionic acetylcholine receptors identifies patients with various forms of autoimmune autonomic neuropathy and distinguishes these disorders from other types of dysautonomia. The positive correlation between high levels of ganglionic-receptor antibodies and the severity of autonomic dysfunction suggests that the antibodies have a pathogenic role in these types of neuropathy.

Idiopathic postural orthostatic tachycardia syndrome: an attenuated form of acute pandysautonomia?

To characterize the idiopathic postural orthostatic tachycardia syndrome (POTS), we reviewed the records of all patients aged 20 to 51 who presented to the Mayo Autonomic Reflex Laboratory and who exhibited tachycardia at rest or during head-up tilt. These patients were usually women who experienced an acute onset of persistent lightheadedness and fatigue or gastrointestinal dysmotility. In seven patients, a viral illness may have preceded the onset of symptoms. In two instances, signs and symptoms of a small-fiber sensory neuropathy were present. Laboratory evaluation of autonomic function revealed increased diastolic blood pressure to tilt (5/16), increased Valsalva ratio, marked decrease in phase II of the Valsalva maneuver with normal phase IV overshoot, and normal forced respiratory sinus arrhythmia. Abnormal quantitative sudomotor axon reflex test and thermoregulatory sweat test and an excessive orthostatic increase of catecholamines were found in some patients. We conclude that in many instances POTS may be a manifestation of a mild form of acute autonomic neuropathy.

Quantitative sudomotor axon reflex test in normal and neuropathic subjects

We have quantified postganglionic sweat output in human subjects resulting from axon reflex stimulation using acetylcholine electrophoresis. Dehumidified nitrogen of controlled temperature and flow rate was passed through an acrylic plastic chamber placed over a defined area of skin. Sweat droplets were evaporated; humidity change was sensed by a narrow-range humidity sensor housed in a temperature-controlled compartment and was plotted on a chart recorder. The time integral (area under the curve) was continuously integrated and converted to absolute units using a derived equation. Because stimulation and recording were simultaneous, an accurate determination of the latency of the sweat response was also possible. Quantitative sudomotor axon reflex tests were performed on the left forearm and foot of 33 female and 29 male normal subjects aged 11 to 69 years. Acetylcholine, 10%, was electrophoresed for 5 mA-minutes in the forearm and 10 mA-minutes in the foot, and recording was continued for an additional 5 minutes. The mean sweat output in males was 2.7 and 3.0 times that in females in forearm and foot, respectively (p less than 0.0001). Studies in selected autonomic neuropathies confirm that quantitative sudomotor axon reflex tests will detect postganglionic sudomotor abnormalities sensitively and reproducibly.

Composite autonomic scoring scale for laboratory quantification of generalized autonomic failure

An autonomic reflex screen, which consisted of a quantitative sudomotor axon reflex test, orthostatic blood pressure and heart rate response to tilt, heart rate response to deep breathing, the Valsalva ratio, and beat-to-beat blood pressure measurements during phases II and IV of the Valsalva maneuver, tilt, and deep breathing, was used to develop a 10-point composite autonomic scoring scale of autonomic function. The scheme allots 4 points for adrenergic and 3 points each for sudomotor and cardiovagal failure. Each score is normalized for the compounding effects of age and sex. Patients with a score of 3 or less on the composite autonomic scoring scale have only mild autonomic failure, those with scores of 7 to 10 have severe failure, and those with scores between these two ranges have moderate autonomic failure. The sensitivity and specificity of the method were assessed by evaluating the composite autonomic scoring scale in four groups of patients with known degrees of autonomic failure: 18 with multisystem atrophy, 20 with autonomic neuropathy, 20 with Parkinson's disease, and 20 with peripheral neuropathy but no autonomic symptoms. The composite scores (means +/- SD) for these four groups, respectively, were as follows: 8.5 +/- 1.3, 8.6 +/- 1.2, 1.5 +/- 1.1, and 1.7 +/- 1.3. Patients with symptomatic autonomic failure had scores of 5 or more, those without symptomatic autonomic failure had scores of 4 or less, and no overlap existed in these groups. Thus, autonomic laboratory tests should be useful in grading the degree of autonomic failure.

Endoneurial blood flow and oxygen tension in the sciatic nerves of rats with experimental diabetic neuropathy

Endoneurial hypoxia has been postulated to be important in the pathogenesis of diabetic peripheral neuropathy and may be due to reduced nerve blood flow. Neither blood flow nor oxygen tension have previously been measured in peripheral nerve in diabetic neuropathy. We have therefore measured both nerve blood flow and endoneurial oxygen tension in the sciatic nerves of 8 rats with streptozotocin-induced diabetes for four months, and in 8 age-matched controls. In 7 of the diabetic animals mean nerve blood flow was 8.7 +/- 1.3 ml X min-1 X 100 g-1 which is significantly less than mean nerve blood flow in the controls (13.08 +/- 0.8 ml X min-1 X 100 g-1; P less than 0.01). In one diabetic animal, nerve blood flow was too low to be accurately measured. The reduction in nerve blood flow in diabetic neuropathy is due to an increase in resistance to flow which may be due to microangiopathy and to blood hyperviscosity. Endoneurial oxygen tension was also significantly reduced in experimental diabetic neuropathy in which 60 per cent of the oxygen measurements were less than 25 mmHg, compared with 19 per cent in the controls. Nerve blood flow was also measured in rats with experimental galactose neuropathy in which there is more marked sugar-alcohol accumulation, endoneurial oedema and elevation of endoneurial fluid pressure than in experimental diabetic neuropathy. The results obtained in this neuropathy suggest that the reduction in nerve blood flow which occurs in experimental diabetic neuropathy is due largely to factors other than sugar-alcohol accumulation in nerve. We postulate that endoneurial hypoxia may produce many of the observed morphological and biochemical changes in experimental diabetic neuropathy.

Treatment of symptomatic diabetic polyneuropathy with the antioxidant alpha-lipoic acid: a meta-analysis

AIMS

To determine the efficacy and safety of 600 mg of alpha-lipoic acid given intravenously over 3 weeks in diabetic patients with symptomatic polyneuropathy.

METHODS

We searched the database of VIATRIS GmbH, Frankfurt, Germany, for clinical trials of alpha-lipoic acid according to the following prerequisites: randomized, double-masked, placebo-controlled, parallel-group trial using alpha-lipoic acid infusions of 600 mg i.v. per day for 3 weeks, except for weekends, in diabetic patients with positive sensory symptoms of polyneuropathy which were scored by the Total Symptom Score (TSS) in the feet on a daily basis. Four trials (ALADIN I, ALADIN III, SYDNEY, NATHAN II) comprised n=1258 patients (alpha-lipoic acid n=716; placebo n=542) met these eligibility criteria and were included in a meta-analysis based on the intention-to-treat principle. Primary analysis involved a comparison of the differences in TSS from baseline to the end of i.v. Treatment between the groups treated with alpha-lipoic acid or placebo. Secondary analyses included daily changes in TSS, responder rates (> or =50% improvement in TSS), individual TSS components, Neuropathy Impairment Score (NIS), NIS of the lower limbs (NIS-LL), individual NIS-LL components, and the rates of adverse events.

RESULTS

After 3 weeks the relative difference in favour of alpha-lipoic acid vs. placebo was 24.1% (13.5, 33.4) (geometric mean with 95% confidence interval) for TSS and 16.0% (5.7, 25.2) for NIS-LL. The responder rates were 52.7% in patients treated with alpha-lipoic acid and 36.9% in those on placebo (P<0.05). On a daily basis there was a continuous increase in the magnitude of TSS improvement in favour of alpha-lipoic acid vs. placebo which was noted first after 8 days of treatment. Among the individual components of the TSS, pain, burning, and numbness decreased in favour of alpha-lipoic acid compared with placebo, while among the NIS-LL components pin-prick and touch-pressure sensation as well as ankle reflexes were improved in favour of alpha-lipoic acid after 3 weeks. The rates of adverse events did not differ between the groups.

CONCLUSIONS

The results of this meta-analysis provide evidence that treatment with alpha-lipoic acid (600 mg/day i.v.) over 3 weeks is safe and significantly improves both positive neuropathic symptoms and neuropathic deficits to a clinically meaningful degree in diabetic patients with symptomatic polyneuropathy.

Plasma exchange in chronic inflammatory demyelinating polyradiculoneuropathy

Plasma exchange has been reported to be efficacious in chronic inflammatory demyelinating polyradiculoneuropathy. We performed a prospective double-blind trial in which patients with static or worsening disease were randomly assigned to plasma exchange (n = 15) or to sham exchange (n = 14) for three weeks. After three weeks, we observed statistically significant differences in combined measurements of nerve conduction (total, motor, proximal, velocity, and amplitude) favoring patients who had received plasma exchange. Improvement to a greater degree than for any patient receiving sham exchange was detected in the neurologic-disability score in five patients (P = 0.025) and in subset scores for weakness and reflex in four patients (P less than 0.057). We conclude that for some patients with chronic inflammatory demyelinating polyradiculoneuropathy, plasma exchange has an ameliorating effect on neurologic dysfunction and nerve conduction, but in others no improvement is observed. Because plasma was replaced with normal serum albumin, a humoral factor or factors may have a role in the neurologic deficit of this disorder.

Prednisone improves chronic inflammatory demyelinating polyradiculoneuropathy more than no treatment

Of 40 patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), 28 completed a controlled three-month trial of prednisone. Prednisone was shown to cause a small but significant improvement over no treatment in scored neurological disability, some measures of computer-assisted sensory detection threshold, graded muscle strength, and some attributes of nerve conduction. No subset of patients was more likely than another to be responsive to prednisone; those with a progressive course were as likely to be responsive as recurrent cases. This finding provides further justification for classifying progressive with recurrent cases as CIDP and demonstrates that prednisone treatment should not be withheld from patients with progressive disease.

A plasma exchange versus immune globulin infusion trial in chronic inflammatory demyelinating polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy is a paralytic syndrome, causing considerable disability and even death. In controlled clinical trials, plasma exchange prevented or ameliorated neurological deficits, but the efficacy of immune globulin infusion remains unproved. Also unknown is whether immune globulin infusion is as effective, or more effective, than plasma exchange and what dosages and frequencies are best. In this observer-blinded study, using some objective end points not subject to bias (e.g., summated compound muscle action potential), 20 patients with progressive or static polyneuropathy were randomly assigned to receive either of the two treatments for 6 weeks, followed by a washout period, and then were assigned to receive the other treatment. Plasma exchange (twice a week for 3 weeks then once a week for 3 weeks) and immune globulin infusion (0.4 gm/kg once a week for 3 weeks, then 0.2 gm/kg once a week for the next 3 weeks) were used. End points assessed before and after treatment schedules were neurological disability score; muscle weakness of the neurological disability score; summated compound muscle action potentials of ulnar, median, and peroneal nerves; summated sensory nerve action potentials of ulnar and sural nerves; and vibratory detection threshold of the great toe using CASE IV. Observers were masked as to treatment used. Of 20 patients, 13 received both treatments whereas 4 did not worsen sufficiently to receive the second treatment--1 patient left the study during and 2 after the first treatment to receive unscheduled treatment elsewhere.(ABSTRACT TRUNCATED AT 250 WORDS)

The roles of oxidative stress and antioxidant treatment in experimental diabetic neuropathy

Oxidative stress is present in the diabetic state. Our work has focused on its presence in peripheral nerves. Antioxidant enzymes are reduced in peripheral nerves and are further reduced in diabetic nerves. That lipid peroxidation will cause neuropathy is supported by evidence of the development of neuropathy de novo when normal nerves are rendered alpha-tocopherol deficient and by the augmentation of the conduction deficit in diabetic nerves subjected to this insult. Oxidative stress appears to be primarily due to the processes of nerve ischemia and hyperglycemia auto-oxidation. The indexes of oxidative stress include an increase in nerve, dorsal root, and sympathetic ganglia lipid hydroperoxides and conjugated dienes. The most reliable and sensitive index, however, is a reduction in reduced glutathione. Experimental diabetic neuropathy results in myelinopathy of dorsal roots and a vacuolar neuropathy of dorsal root ganglion. The vacuoles are mitochondrial; we posit that lipid peroxidation causes mitochondrial DNA mutations that increase reduced oxygen species, causing further damage to mitochondrial respiratory chain and function and resulting in a sensory neuropathy. Alpha-lipoic acid is a potent antioxidant that prevents lipid peroxidation in vitro and in vivo. We evaluated the efficacy of the drug in doses of 20, 50, and 100 mg/kg administered intraperitoneally in preventing the biochemical, electrophysiological, and nerve blood flow deficits in the peripheral nerves of experimental diabetic neuropathy. Alpha-lipoic acid dose- and time-dependently prevented the deficits in nerve conduction and nerve blood flow and biochemical abnormalities (reductions in reduced glutathione and lipid peroxidation). The nerve blood flow deficit was 50% (P < 0.001). Supplementation dose-dependently prevented the deficit; at the highest concentration, nerve blood flow was not different from that of control nerves. Digital nerve conduction underwent a dose-dependent improvement at 1 month (P < 0.05). By 3 months, all treated groups had lost their deficit. The antioxidant drug is potentially efficacious for human diabetic sensory neuropathy.

Lipoic acid improves nerve blood flow, reduces oxidative stress, and improves distal nerve conduction in experimental diabetic neuropathy

OBJECTIVE

To determine whether lipoic acid (LA) will reduce oxidative stress in diabetic peripheral nerves and improve neuropathy.

RESEARCH DESIGN AND METHODS

We used the model of streptozotocin-induced diabetic neuropathy (SDN) and evaluated the efficacy of LA supplementation in improving nerve blood flow (NBF), electrophysiology, and indexes of oxidative stress in peripheral nerves affected by SDN, at 1 month after onset of diabetes and in age-matched control rats. LA, in doses of 20, 50, and 100 mg/kg, was administered intraperitoneally five times per week after onset of diabetes.

RESULTS

NBF in SDN was reduced by 50%; LA did not affect the NBF of normal nerves but improved that of SDN in a dose-dependent manner. After 1 month of treatment, LA-supplemented rats (100 mg/kg) exhibited normal NBF. The most sensitive and reliable indicator of oxidative stress was reduction in reduced glutathione, which was significantly reduced in streptozotocin-induced diabetic and alpha-tocopherol-deficient nerves; it was improved in a dose-dependent manner in LA-supplemented rats. The conduction velocity of the digital nerve was reduced in SDN and was significantly improved by LA.

CONCLUSIONS

These studies suggest that LA improves SDN, in significant part by reducing the effects of oxidative stress. The drug may have potential in the treatment of human diabetic neuropathy.

Efficacy of midodrine vs placebo in neurogenic orthostatic hypotension. A randomized, double-blind multicenter study. Midodrine Study Group

OBJECTIVE

To evaluate the efficacy of a 10-mg dose of midodrine 3 times per day in improving blood pressure (BP) and ameliorating symptoms of orthostatic hypotension in patients with neurogenic orthostatic hypotension. Midodrine hydrochloride, an alpha-agonist, could improve orthostatic BP by increasing vasomotor and venomotor tone.

DESIGN/METHODS

A total of 171 patients with orthostatic hypotension participated in a multicenter, randomized, placebo-controlled study. They were randomized to a 10-mg dose of midodrine or placebo 3 times per day in a 6-week study, comprising single-blind run-in (at week 1) and washout at weeks 5 and 6, with an intervening double-blind period (weeks 2 to 4).

SETTING

Twenty-five centers, with most patients evaluated in referral centers.

MAIN OUTCOME MEASURES

The primary end points were improvement in standing systolic BP, symptoms of lightheadedness, and a global symptom relief score (by the investigator and patient separately).

RESULTS

Nine patients were not evaluable because of noncompliance or taking concomitant vasoactive medications (3 in the midodrine group, 6 in the placebo group). In the evaluable patients, midodrine resulted in improvements in standing systolic BP at all time points (P<.001 at visits 2, 3, 4, and 5), in reported symptoms by the end of the second week of treatment (P=.001), and in the global symptom relief score rated by both the patient (P=.03) and the investigator (P<.001). There was no effect by center, severity of orthostatic hypotension, use of fludrocortisone or compression garments, or diagnosis. The main adverse effects were those of pilomotor reactions, urinary retention, and supine hypertension.

CONCLUSIONS

Midodrine is efficacious and safe in the treatment of neurogenic orthostatic hypotension.

Ataxic sensory neuropathy and dorsal root ganglionitis associated with Sjögren's syndrome

Thirteen patients, 11 women and 2 men, developed sensory and autonomic neuronopathies in association with features of primary Sjögren's syndrome. In 11, Sjögren's syndrome had not been previously diagnosed at the time of neurological presentation. All had prominent loss of kinesthesia and proprioception. Pain and thermal sensibility were less severely affected. Most had evidence of autonomic insufficiency. In some this was severe, with Adie's pupils, fixed tachycardia, and orthostatic hypotension. The course ranged from an abrupt, devastating onset to indolent progression over years. Stabilization or functional improvement occurred in 6 patients, 2 of whom received no drug therapy. Sensory nerve conduction studies and examination of nerve biopsy specimens demonstrated a wide spectrum in the severity of loss of large myelinated fibers. The cutaneous nerves of 6 patients had perivascular mononuclear infiltrates without necrotizing arteritis. Examination of biopsy specimens of dorsal root ganglia in 3 patients revealed lymphocytic (T-cell) infiltration in the dorsal roots and ganglia, with focal clusters around neurons. In the more mildly affected ganglia, individual sensory neurons were undergoing degeneration. In the most advanced case, very few neurons remained. The possibility of Sjögren's syndrome should be considered in patients, especially women, who develop acute, subacute, or chronic sensory and autonomic neuropathies, with ataxia and kinesthetic loss.

Nonsystemic vasculitic neuropathy

Among 65 patients with necrotizing vasculitis, 45 had systemic and 20 had nonsystemic vasculitic neuropathy. In nonsystemic vasculitic neuropathy, clinically only nerves are affected; there are no, or few, constitutional symptoms or serological abnormalities. The clinical and pathological features are those of an ischaemic neuropathy caused by a necrotizing vasculitis of small arterioles. These 20 patients had neuropathic symptoms for a median time of 11.5 yrs (range 1-35 yrs). The clinical pattern of neuropathy was that of multiple mononeuropathy in 13, asymmetric neuropathy in 4, distal polyneuropathy in 3, and sensory polyneuropathy in 1. As compared with their initial evaluation, 8 are now worse, 5 are better, 4 are approximately the same, and 3 are dead from unrelated causes. Prednisone was thought to prevent the development of new lesions in some cases. By contrast, of the 41 patients with systemic necrotizing vasculitis whose outcome is known, 12 are dead (median time, 1.5 yrs, range 3 months-8 yrs) and 29 are alive (median time, 6 yrs, range 6 months-22 yrs).

The Autonomic Symptom Profile: a new instrument to assess autonomic symptoms

OBJECTIVE

To develop a new specific instrument called the Autonomic Symptom Profile to measure autonomic symptoms and test its validity.

BACKGROUND

Measuring symptoms is important in the evaluation of quality of life outcomes. There is no validated, self-completed questionnaire on the symptoms of patients with autonomic disorders.

METHODS

The questionnaire is 169 items concerning different aspects of autonomic symptoms. The Composite Autonomic Symptom Scale (COMPASS) with item-weighting was established; higher scores indicate more or worse symptoms. Autonomic function tests were performed to generate the Composite Autonomic Scoring Scale (CASS) and to quantify autonomic deficits. We compared the results of the COMPASS with the CASS derived from the Autonomic Reflex Screen to evaluate validity.

RESULTS

The instrument was tested in 41 healthy controls (mean age 46.6 years), 33 patients with nonautonomic peripheral neuropathies (mean age 59.5 years), and 39 patients with autonomic failure (mean age 61.1 years). COMPASS scores correlated well with the CASS, demonstrating an acceptable level of content and criterion validity. The mean (+/-SD) overall COMPASS score was 9.8 (+/-9) in controls, 25.9 (+/-17.9) in the patients with nonautonomic peripheral neuropathies, and 52.3 (+/-24.2) in the autonomic failure group. Scores of symptoms of orthostatic intolerance and secretomotor dysfunction best predicted the CASS on multiple stepwise regression analysis.

CONCLUSIONS

We describe a questionnaire that measures autonomic symptoms and present evidence for its validity. The instrument shows promise in assessing autonomic symptoms in clinical trials and epidemiologic studies.

Pathophysiological basis of orthostatic hypotension in autonomic failure

In patients with autonomic failure orthostatic hypotension results from an impaired capacity to increase vascular resistance during standing. This fundamental defect leads to increased downward pooling of venous blood and a consequent reduction in stroke volume and cardiac output that exaggerates the orthostatic fall in blood pressure. The location of excessive venous blood pooling has not been established so far, but present data suggest that the abdominal compartment and perhaps leg skin vasculature are the most likely candidates. To improve the orthostatic tolerance in patients with autonomic failure, protective measures that reduce excessive orthostatic blood pooling have been developed and evaluated. These measures include physical counter-manoeuvres and abdominal compression.

The Rochester Diabetic Neuropathy Study: design, criteria for types of neuropathy, selection bias, and reproducibility of neuropathic tests

A cross-sectional survey and subsequent longitudinal study among diabetic residents of Rochester, MN--The Rochester Diabetic Neuropathy Study (RDNS)--is population-based and uses quantitative, validated, and unique end points to detect, classify, and stage neuropathy. Nondiabetic persons, drawn from the same population, serve as controls. For patients 10 to 70 years old, the RDNS cohort is representative of diabetics living in Rochester, MN. We assessed reproducibility of tests used to characterize and quantitate severity of neuropathy in 20 diabetic subjects without neuropathy and with varying severities of neuropathy. Using intraclass correlation coefficient (rI) as a measure of test reproducibility, we found high rI (usually 0.9 or better) with small confidence intervals for the Neurologic Disability Score (NDS); weakness subset of NDS (W-NDS); vibratory and cooling detection thresholds (using computer-assisted sensory examination [CASE] IV); compound muscle action potentials; sensory nerve action potentials; and motor nerve conduction velocities. There was good agreement among three trained observers for NDS and the W-NDS.

A double-blind, dose-response study of midodrine in neurogenic orthostatic hypotension

OBJECTIVE

To determine the best therapeutic strategy for the use of midodrine in patients with neurogenic orthostatic hypotension (NOH).

BACKGROUND

Midodrine is a peripherally acting alpha-adrenergic agonist useful in the treatment of NOH. However, neither the most effective dosage of midodrine nor the required frequency of administration is established.

DESIGN/METHODS

Midodrine dose-blood pressure response, pharmacokinetics, and duration of action were examined in a double-blind, placebo-controlled, four-way crossover trial. Twenty-five patients with NOH were randomized to receive on successive days placebo or midodrine 2.5, 10, or 20 mg. Blood pressures of patients in the supine and standing positions were measured sequentially. A global assessment of the patient's overall symptom improvement after each leg of the study was performed. Blood levels of midodrine and its active metabolite, desglymidodrine, were assayed.

RESULTS

Midodrine significantly increased standing systolic blood pressure, with the increase peaking at 1 hour. There was a significant linear relation between midodrine dosage and mean systolic blood pressure. The mean score for global improvement of symptoms was significantly higher for midodrine (10 and 20 mg) compared with placebo. The half-life of desglymidodrine was approximately 4 hours.

CONCLUSION

A 10-mg dose of midodrine prescribed two to three times daily is effective in increasing orthostatic blood pressure and ameliorating symptoms in patients with NOH.

Thermoregulatory sweating abnormalities in diabetes mellitus

A properly performed thermoregulatory sweat test (TST) can be informative in patients with diabetic neuropathy. Of 51 patients suspected of having neuropathy on the basis of a clinical examination, 48 (94%) had unequivocal abnormalities on the TST. Pathologic loss of sweating occurred distally in 65%, segmentally in 25%, and only in isolated dermatomes in 25%; 78% of patients had a combination of two or more patterns. Global anhidrosis was noted in eight patients (16%), all of whom had profound autonomic neuropathy, and in the entire group, the percentage of body surface anhidrosis correlated with the degree of clinical dysautonomia (rank correlation coefficient = 0.77; P less than 0.01). Discrete zones of anhidrosis on the thorax and abdomen were noted in patients with painful diabetic radiculopathy, and they correlated highly with thoracic paraspinal muscle fibrillation potentials. Distal loss of sweating detected on the TST was always associated with a subnormal quantitative sudomotor axon reflex response or abnormal electromyographic findings, an indication of a distal axonal neuropathy. The TST provides reliable information about the distribution of diabetic neuropathic involvement and can be especially useful in the diagnosis of truncal radiculopathy and clinically significant autonomic neuropathy.

Plasma exchange in polyneuropathy associated with monoclonal gammopathy of undetermined significance

BACKGROUND

Polyneuropathy associated with monoclonal gammopathy of undetermined significance (MGUS) has been treated with plasma exchange, intravenous immune globulin, and chemotherapy, but the effectiveness of these treatments remains uncertain.

METHODS

We randomly assigned 39 patients with stable or worsening neuropathy and MGUS of the IgG, IgA, or IgM type to receive either plasma exchange twice weekly for three weeks or sham plasma exchange, in a double-blind trial. The patients who initially underwent sham plasma exchange subsequently underwent plasma exchange in an open trial.

RESULTS

In the double-blind trial, the average neuropathy disability score improved by 2 points from base line (from 62.5 to 60.5) in the sham-exchange group and by 12 points (from 58.3 to 46.3) in the plasma-exchange group (P = 0.06). A similar difference was observed in the weakness score, a component of the neuropathy disability score (improvement, 1 and 10 points, respectively; P = 0.07). After treatment the summed compound muscle action potentials of motor nerves were 1.2 mV lower (worse) than at base line in the sham-exchange group and 0.4 mV higher (better) in the plasma-exchange group (P = 0.07). The greater degree of improvement with plasma exchange was equal in magnitude to or greater than the difference between not being able to walk on the heels or toes and being able to perform these activities. Changes in the vibratory detection threshold, summed motor-nerve conduction velocity, and sensory-nerve action potentials did not differ significantly between the treatment groups. In the open trial, in which patients who initially underwent sham exchange were treated with plasma exchange, the neuropathy disability score (P = 0.04), weakness score (P = 0.07), and summed compound muscle action potentials (P = 0.07) improved more with plasma exchange than they had with sham exchange. In both the double-blind and the open trial, those with IgG or IgA gammopathy had a better response to plasma exchange than those with IgM gammopathy.

CONCLUSIONS

Plasma exchange appears to be efficacious in neuropathy associated with MGUS, especially of the IgG or IgA type.

3,4-Diaminopyridine in the treatment of Lambert-Eaton myasthenic syndrome

Lambert-Eaton myasthenic syndrome is characterized by muscle weakness, hyporeflexia, and autonomic dysfunction, which result from impaired release of acetylcholine from cholinergic nerve terminals. It is frequently associated with cancer, it is autoimmune-mediated, and treatment has been unsatisfactory. 3,4-Diaminopyridine enhances the release of acetylcholine. In this prospective, double-blind, placebo-controlled crossover study of 12 patients with Lambert-Eaton myasthenic syndrome (7 of whom had cancer), 3,4-diaminopyridine in doses up to 100 mg per day was effective in treating both the motor and the autonomic deficits of the syndrome. Muscle strength increased from an average of 70 percent of normal to 81 percent of normal in the upper extremities, and from 45 to 65 percent of normal in the lower extremities. The amplitudes of compound-muscle-action potentials nearly doubled, increasing from an average of 2.9 mV to 5.0 mV in the arm and from 1.6 mV to 3.1 mV in the leg. Autonomic symptoms were relieved. One patient had a seizure after 10 months of treatment, but other side effects from the drug were minimal and dose-related. We conclude that 3,4-diaminopyridine, either alone or in conjunction with other therapies, may be useful in the treatment of Lambert-Eaton myasthenic syndrome.

Practice Parameter: evaluation of distal symmetric polyneuropathy: role of autonomic testing, nerve biopsy, and skin biopsy (an evidence-based review). Report of the American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine, and American Academy of Physical Medicine and Rehabilitation

BACKGROUND

Distal symmetric polyneuropathy (DSP) is the most common variety of neuropathy. Since the evaluation of this disorder is not standardized, the available literature was reviewed to provide evidence-based guidelines regarding the role of autonomic testing, nerve biopsy, and skin biopsy for the assessment of polyneuropathy.

METHODS

A literature review using MEDLINE, EMBASE, and Current Contents was performed to identify the best evidence regarding the evaluation of polyneuropathy published between 1980 and March 2007. Articles were classified according to a four-tiered level of evidence scheme and recommendations were based upon the level of evidence.

RESULTS AND RECOMMENDATIONS

1) Autonomic testing should be considered in the evaluation of patients with polyneuropathy to document autonomic nervous system dysfunction (Level B). Such testing should be considered especially for the evaluation of suspected autonomic neuropathy (Level B) and distal small fiber sensory polyneuropathy (SFSN) (Level C). A battery of validated tests is recommended to achieve the highest diagnostic accuracy (Level B). 2) Nerve biopsy is generally accepted as useful in the evaluation of certain neuropathies as in patients with suspected amyloid neuropathy, mononeuropathy multiplex due to vasculitis, or with atypical forms of chronic inflammatory demyelinating polyneuropathy (CIDP). However, the literature is insufficient to provide a recommendation regarding when a nerve biopsy may be useful in the evaluation of DSP (Level U). 3) Skin biopsy is a validated technique for determining intraepidermal nerve fiber density and may be considered for the diagnosis of DSP, particularly SFSN (Level C). There is a need for additional prospective studies to define more exact guidelines for the evaluation of polyneuropathy.