Myelin protein zero mutation His39Pro: hereditary motor and sensory neuropathy with variable onset, hearing loss, restless legs and multiple sclerosis

BACKGROUND

Mutations of myelin protein zero (MPZ) may cause inherited neuropathy with variable expression.

OBJECTIVE

To report phenotypic variability in a large American kindred with MPZ mutation His39Pro.

PATIENTS

Genetic testing was performed on 77 family members and 200 controls. Clinical and electrophysiological field study assessments were available for review in 47 family members.

RESULTS

His39Pro was found in all 10 individuals prospectively identified with neuropathy. 200 normal controls were without mutation. Symptoms of neuropathy began in adulthood and were slowly progressive except for one acute-onset painful sensory neuropathy. Associated features included premature hearing loss (n = 7), nocturnal restless leg symptoms (n = 8) and multiple sclerosis in one.

CONCLUSIONS

MPZ mutation His39Pro may be associated with acute-onset neuropathy, early-onset hearing loss and restless legs. The relationship with multiple sclerosis in the proband remains uncertain.

The gene for HMSN2C maps to 12q23-24: a region of neuromuscular disorders

BACKGROUND

Hereditary motor and sensory neuropathy type 2C (HMSN2C, Charcot-Marie-Tooth 2C [CMT2C]) is an autosomal dominant motor and sensory neuropathy involving limb, diaphragm, vocal cord, and intercostal muscles.

OBJECTIVE

To identify the chromosome localization for this disorder in one large American family of English and Scottish ethnicity.

METHODS

Variable clinical severity led the authors to combine several approaches to accurately identify affected patients. Genome-wide two-point linkage analysis, high-definition mapping, and multipoint and recombinant haplotype analyses were performed. Mutation analysis of the triplet repeat region of ataxin-2 was also carried out.

RESULTS

The initial genome-wide scan identified a region at 12q24, and fine mapping provided a maximal lod score of 4.73 (D12S1645 and D12S1583 at theta = 0.01 and 0, respectively). With multipoint analysis, a higher lod score of 5.17 was obtained and localized to the same region at 119.0 cM. Haplotype analysis narrowed the region to approximately 5.0 cM between D12S1646,D12S1330 and D12S105,D12S1339 (12q23.3-24.21). Ataxin-2, the gene responsible for spinocerebellar ataxia type 2 (SCA2), localizes to this region, but no triplet repeat expansion or point mutations within the repeat were found.

CONCLUSIONS

The gene for HMSN2C maps to 12q23-24. This region is associated with SCA2, scapuloperoneal spinal muscular atrophy, and congenital distal spinal muscular atrophy. Further studies are needed to demonstrate the specific gene alteration and its relationship with nearby genes.

Guamanian neurodegenerative disease: electrophysiologic findings

Amyotrophic lateral sclerosis (ALS), parkinsonism and/or dementia are highly prevalent among the Chamorro population of Guam. The incidence of Guamanian ALS has markedly declined in recent years, but these incidence figures may reflect underascertainment of subclinical disease. Guamanian Chamorro patients have not been systematically studied using modern clinical neurophysiological techniques. Electromyography (EMG: needle exam and nerve conduction studies) was used to study 29 patients with the major subtypes of Guamanian neurodegenerative disease, as well as 11 neurologically normal Guamanian Chamorro subjects. Central conduction was assessed by somatosensory evoked potentials (SEP's) in 16 patients. EMG evidence of peripheral neuropathy, (often subclinical) was found in 45% of Guamanian patients but no Chamorro control subjects. Diabetes mellitus, which is highly prevalent in this population, was present in some, but not all of these cases. Clinically unsuspected motor neuron disease was identified by EMG in only one of the 23 Guamanian patients with parkinsonism and/or dementia and in none of the 11 Chamorro control subjects. Two of seven patients with the clinical phenotype of Guamanian ALS had a more benign EMG pattern on the needle electrode exam with absence of fibrillation and fasciculation potentials. Three of 16 patients (all with parkinsonism and dementia) had mildly abnormal tibial SEP's. No patient had EMG evidence of myopathy or a defect of neuromuscular transmission. We conclude: (1) peripheral neuropathy may be a manifestation of Guamanian neurodegenerative disease; (2) the declining prevalence of ALS on Guam is not associated with the development of a subclinical form of motor neuron disease; (3) the substantial overlap of Guamanian ALS with parkinsonism-dementia reported in prior decades is no longer apparent; (4) abnormal central conduction, as assessed by tibial SEP's, is present in some patients with Guamanian parkinsonism-dementia.

In-vivo function of the thumb muscles

OBJECTIVE

The purpose of this study is to quantify the electrical activity of the thumb muscles responsible for the production of force in different directions of thumb movement.

DESIGN

The isometric forces and electromyographic activity generated by seven thumb muscles were measured on five normal healthy test subjects.

BACKGROUND

The thumb is very important for proper hand function. Presently available electromyographic studies of the thumb muscles provide only limited information. Most thumb muscles have more than one function. Additional studies are required to carefully examine and confirm the in-vivo relationship between the thumb muscle electromyogram and mechanical output.

METHODS

The direction and magnitude of the force vector generated at the interphalangeal joint and the relative electrical activity were obtained for eight directions of thumb action. The regions of function were defined for the abductor pollicis brevis, opponens pollicis, flexor pollicis brevis, adductor pollicis, flexor pollicis longus, extensor pollicis longus, and the abductor pollicis longus. Data was collected during voluntary isometric contraction, both before and after blocking the median nerve at the wrist.

RESULTS

The highest force production was obtained during flexion. The region of maximal muscle electrical activity varied for each muscle studied. The areas of maximal in-vivo muscle activity agreed with the moment arm data reported in the literature. The median nerve block eliminated the ability to produce force in abduction.

CONCLUSIONS

This study has demonstrated that by combining electromyographic measurement and biomechanical analysis it is possible to confirm the relationship between in-vivo thumb muscle function and muscle mechanics in a novel manner. The findings of this study indicate the importance of the local anatomy in controlling the direction of force production.

Recombinant human nerve growth factor in the treatment of diabetic polyneuropathy. NGF Study Group

BACKGROUND

Preclinical studies have demonstrated that nerve growth factor may prevent or reverse peripheral neuropathy. We have therefore tested the effects of recombinant human nerve growth factor in patients with diabetic polyneuropathy.

METHODS

A total of 250 patients with symptomatic diabetic polyneuropathy randomly received either placebo or one of two doses of recombinant human nerve growth factor for 6 months. Patients were assessed for symptoms and signs of polyneuropathy before and after treatment.

RESULTS

Compared with placebo, recombinant human nerve growth factor led to significant improvement after 6 months of treatment, as measured by the sensory component of the neurologic examination, two quantitative sensory tests, and the impression of most subjects that their neuropathy had improved. Three prospectively identified multiple endpoint analyses indicated improvements in the nerve growth factor treatment groups over the placebo group in all three analyses (p = 0.032; p = 0.008; p = 0.005). Recombinant human nerve growth factor was well tolerated, with injection site discomfort reported as the most frequent adverse event.

CONCLUSIONS

Recombinant human nerve growth factor appears to be safe and shows preliminary evidence of efficacy in patients with symptomatic diabetic polyneuropathy.

Subacute diabetic proximal neuropathy

OBJECTIVE

To evaluate the clinical, electrophysiologic, autonomic, and neuropathologic characteristics and the natural history of subacute diabetic proximal neuropathy and its response to immunotherapy.

MATERIAL AND METHODS

For the 12-year period from 1983 to 1995, we conducted a retrospective review of medical records of Mayo Clinic patients with diabetes who had subacute onset and progression of proximal weakness. The responses of treated versus untreated patients were compared statistically.

RESULTS

During the designated study period, 44 patients with subacute diabetic proximal neuropathy were encountered. Most patients were middle-aged or elderly, and no sex preponderance was noted. The proximal muscle weakness often was associated with reduced or absent lower extremity reflexes. Associated weight loss was a common finding. Frequently, patients had some evidence of demyelination on nerve conduction studies, but it invariably was accompanied by concomitant axonal degeneration. The cerebrospinal fluid protein concentration was usually increased. Diffuse and substantial autonomic failure was generally present. In most cases, a sural nerve biopsy specimen suggested demyelination, although evidence of an inflammatory infiltrate was less common. Of 12 patients who received treatment (with prednisone, intravenous immune globulin, or plasma exchange), 9 had improvement of their conditions, but 17 of 29 untreated patients (59%) with follow-up also eventually had improvement, albeit at a much slower rate. Improvement was usually incomplete.

CONCLUSION

We suggest that the entity of subacute diabetic proximal neuropathy is an extensive and severe variant of bilateral lumbosacral radiculoplexopathy, with some features suggestive of an immune-mediated cause. It differs from chronic inflammatory demyelinating polyradiculoneuropathy in that most cases have a more restricted distribution and seem to be monophasic and self-limiting. The efficacy of immunotherapy is unproved, but such intervention may be considered in the severe and progressive cases or ones associated with severe neuropathic pain.

Longitudinal assessment of diabetic polyneuropathy using a composite score in the Rochester Diabetic Neuropathy Study cohort

Because there are little satisfactory data on change in severity of diabetic polyneuropathy (DP) over time from study of population-based cohorts of diabetic patients in epidemiologic surveys of DP, it is difficult to predict outcome or morbidity or to identify risk factors; it is also difficult to estimate statistical power for use in controlled clinical trials. In this longitudinal study of almost 200 patients from the Rochester Diabetic Neuropathy Study (RDNS) cohort, we assess which symptoms, clinical examinations, tests, or combinations of examinations and tests (composite scores) are best used as minimal criteria for the diagnosis of DP and as a quantitative measure of severity of DP. An abnormality (> or = 97.5th percentile) of a composite score that included the Neuropathy Impairment Score of the lower limbs plus seven tests (NIS(LL)+7 tests), was a better minimal criteria for DP than clinical judgment alone or previously published minimal criteria. First, it provided a more comprehensive assessment of neuropathic impairment. Second, it avoided the overestimated frequency of DP when the minimal criteria for DP was any one or two abnormalities from multiple measurements. Minimal criteria using nerve conduction and reduced heart beat response to deep breathing identified approximately twice as many patients with DP than did clinical examination and vibration detection threshold using CASE IV. This difference could be used to subclassify state 1 DP. Although various individual measures of DP, for example, vibration detection threshold (as evaluated by CASE IV and the 4, 2, and 1 stepping algorithm [see text]), were good measures of worsening, the composite score NIS(LL)+7 tests (assessing neuropathic impairment) was much better at showing monotone worsening. Using this composite score, the average diabetic patient in the RDNS worsened by 0.34 points per year, whereas patients with diabetic polyneuropathy worsened by 0.85 points per year. On the assumption that a therapeutic agent may prevent worsening of DP but not cause improvement, controlled clinical trials of patients with DP would need to be conducted for a period of 3 years to achieve a meaningful change of 2 NIS points (the level of abnormality considered by a Peripheral Nerve Society consensus group to be clinically meaningful).

Randomized prospective trial comparing ileal pouch-anal anastomosis performed by excising the anal mucosa to ileal pouch-anal anastomosis performed by preserving the anal mucosa

OBJECTIVE

The purpose of the study is to compare the results of ileal pouch-anal anastomosis (IPAA) in patients in whom the anal mucosa is excised by handsewn techniques to those in whom the mucosa is preserved using stapling techniques.

SUMMARY BACKGROUND DATA

Ileal pouch-anal anastomosis is the operation of choice for patients with chronic ulcerative colitis requiring proctocolectomy. Controversy exists over whether preserving the transitional mucosa of the anal canal improves outcomes.

METHODS

Forty-one patients (23 men, 18 women) were randomized to either endorectal mucosectomy and handsewn IPAA or to double-stapled IPAA, which spared the anal transition zone. All patients were diverted for 2 to 3 months. Nine patients were excluded. Preoperative functional status was assessed by questionnaire and anal manometry. Twenty-four patients underwent more extensive physiologic evaluation, including scintigraphic anopouch angle studies and pudendel never terminal motor latency a mean of 6 months after surgery. Quality of life similarly was estimated before surgery and after surgery. Univariate analysis using Wilcoxon test was used to assess differences between groups.

RESULTS

The two groups were identical demographically. Overall outcomes in both groups were good. Thirty-three percent of patients who underwent the handsewn technique and 35% of patients who underwent the double-stapled technique experienced a postoperative complication. Resting anal canal pressures were higher in the patients who underwent the stapled technique, but other physiologic parameters were similar between groups. Night-time fecal incontinence occurred less frequently in the stapled group but not significantly. The number of stools per 24 hours decreased from preoperative values in both groups. After IPAA, quality of life improved promptly in both groups.

CONCLUSIONS

Stapled IPAA, which preserves the mucosa of the anal transition zone, confers no apparent early advantage in terms of decreased stool frequency or fewer episodes of fecal incontinence compared to handsewn IPAA, which excises the mucosa. Higher resting pressures in the stapled group coupled with a trend toward less night-time incontinence, however, may portend better function in the stapled group over time. Both operations are safe and result in rapid and profound improvement in quality of life.

Neuromuscular complications associated with liver transplantation

We studied neuromuscular complications in a cohort of 520 patients with liver transplantation. Perioperative mononeuropathy developed in 9 patients. The peroneal nerve, radial nerve, and cutaneous branch of the femoral nerve were affected in 2 patients each. Two patients had herpes zoster-associated radiculopathy, and 1 patient had Horner's syndrome. Recovery was good in most patients. In 7 patients, severe quadriplegia complicated the perioperative course. In 5 patients, electrophysiologic studies suggested acute necrotic myopathy, and muscle biopsy specimens showed evidence of rhabdomyolysis in 1 patient. Outcome in survivors was good, all recovering completely. We conclude that neuromuscular complications in liver transplantation are uncommon (less than 1%) and do not significantly contribute to morbidity. Mononeuropathies may have iatrogenic perioperative causes, and rhabdomyolysis may be an important cause of generalized muscle weakness after liver transplantation.

Lack of progression of neurologic deficit in survivors of paralytic polio: a 5-year prospective population-based study

We completed a prospective, population-based cohort study of polio survivors in Olmsted County, Minnesota, between 1986 and 1993. We identified 50 individuals who had had paralytic polio between 1935 and 1960, as representative of all 300 cases of paralytic polio in the county. We completed detailed quantitative clinical and electrophysiologic studies at entry and after 5 years. These studies demonstrated stable neuromuscular function within the cohort, although 60% of the individuals were symptomatic. In two-thirds of the symptomatic patients, the causes of their symptoms were unrelated to earlier polio. For the 20% of patients who had unexplained muscle pain, perception of weakness, and fatigue, a mechanical disorder most likely underlies their symptoms.

Far-field auditory brainstem response in neurotologic surgery

This is a review of our experience using far-field auditory brainstem monitoring during acoustic neuroma removal. The observations are based on 144 consecutive cases beginning in 1986. The factors of importance are tumor size, preoperative auditory function, and the preoperative presence of a wave V on the auditory brainstem response. Our experience suggests that preservation of hearing in tumors > 2.5 cm is rare. It was observed that preserving wave V does not guarantee preservation of hearing. Conversely, loss of wave V does not preclude preservation of hearing. It has also been noted that the presence of only wave I preoperatively does offer some hope that hearing can be preserved postoperatively. Finally, postoperative hearing function is usually equal to or worse than the preoperative function. Only rarely does the postoperative function improve.

Variables influencing neuropathic endpoints: the Rochester Diabetic Neuropathy Study of Healthy Subjects

We determined the normal limits for various neuropathic tests in healthy subjects. The study, the Rochester Diabetic Neuropathy Study (RDNS), is noteworthy because of its size (more than 400 subjects), random selection of subjects, and selection of at least 15 men and 15 women without neuropathy, neurologic disease, or diseases predisposing to neuropathy from each hemidecade between 18 and 74 years of age from the population of a defined region (Rochester, MN). Subjects were classified into those with (nonhealthy subjects, RDNS-NS) and without (healthy subjects, RDNS-HS) neuropathy, neurologic or psychiatric disease, or diseases known to predispose to neuropathy. The study provides normal limits for tests used in the RDNS but it has broader uses as well. We found that (1) less than 10% of subjects in the third decade, approximately 20% in the fourth decade, and approximately 30% in the fifth or older decades were placed into the RDNS-NS category; (2) healthy subjects (RDNS-HS) retain their ability to walk on toes and heels regardless of age, excessive weight, or lack of physical fitness, but not their ability to arise from a kneeled position--lost in more than 5% of persons 60 years and older; (3) the frequency of decreased or absent ankle reflexes exceeds 5% in healthy subjects older than 50 years--limiting their value as a sign of diabetic polyneuropathy and necessitating a grading change with age in the neuropathy impairment score.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of botulinum toxin type A injection on compound muscle action potential in an in vivo rat model

Serial measurements were performed on the compound muscle action potential (CMAP) amplitude and the force generated by the rat lower hind limb flexors to investigate the time course of intramuscular injections of botulinum toxin type A (BOTOX). Thirty animals were used in this in vivo rat model. CMAP amplitude and muscle force were measured at predetermined intervals for 28 weeks. Compound muscle action potential amplitude and force declined markedly the first 5 to 7 days after injection of BOTOX but recovered in a near linear manner. The response magnitude and recovery rate were dose-dependent. Recovery of CMAP amplitude preceded recovery of muscle force. No clear evidence of a systemic effect on the untreated leg or a concentration effect was found. CMAP amplitude may be useful in determining optimal timing of repeat injections in treating neuromuscular disorders.

Electromyographic studies of the reconstructed lower eyelid after a modified Hughes procedure

PURPOSE

We evaluated quantitatively, with electromyography, the function of orbicularis oculi muscle flaps in modified Hughes reconstructions of the lower eyelids.

METHODS

A modified Hughes procedure with a bipedicle orbicularis oculi flap was used to reconstruct large left lower eyelid defects after tumor excision in six consecutive patients. Standard needle electromyography and facial nerve conduction studies were performed on each reconstructed lower eyelid, and results were compared with those of the unoperated-on right lower eyelid. Electromyographic studies were performed between 143 and 517 days after division of the tarsoconjunctival flap.

RESULTS

Blink reflexes and results of facial nerve studies were normal and similar on both sides. All operated-on eyelids demonstrated electromyographic activity during voluntary orbicularis contraction. The functional and cosmetic results were satisfactory in all patients. No complications of reconstruction, such as eyelid retraction, ectropion, tissue necrosis, or abnormal contour or thickness, occurred.

CONCLUSIONS

A modified Hughes procedure using a bipedicle orbicularis oculi flap provides viable, electrically active muscle to the reconstructed lower eyelid and may enhance the functional results.

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 clinical spectrum of critical illness polyneuropathy

OBJECTIVE

To describe the entity of critical illness polyneuropathy and review our experience with six cases.

DESIGN

We present case reports of six patients with polyneuropathy associated with critical illness, who received medical care at the Mayo Clinic between 1992 and 1994, and discuss similar cases from the literature.

RESULTS

Critical illness may damage peripheral nerves. In previous studies, sepsis and multiorgan failure have been found to trigger a peripheral neuropathy. Of our six patients with critical illness polyneuropathy, all had a preceding severe bacterial infection or septic shock. In one patient who had long-term administration of vecuronium bromide and had received massive intravenous doses of corticosteroids, sural nerve and quadriceps muscle biopsy specimens were available; they revealed axonal neuropathy and notable myopathic changes, respectively. The outcome was good in patients who survived the critical illness.

CONCLUSION

Polyneuropathy in critically ill patients may be a cause of severe generalized limb weakness and occurs in the setting of a sepsis syndrome. The long-term outcome is good in patients who recover from the underlying critical illness. Compression neuropathies may be a cause of permanent sequelae.

Hereditary motor and sensory neuropathy with diaphragm and vocal cord paresis

We describe two kindreds with an autosomal dominant inherited disorder characterized by a variable degree of muscle weakness of limbs, vocal cords, and intercostal muscles and by asymptomatic sensory loss, beginning in infancy or childhood in severely affected persons. Life expectancy in severely affected patients is shortened because of respiratory failure. Because nerve conduction velocities are normal and it is an inherited axonal neuropathy, we classify the disorder as a variety of hereditary motor and sensory neuropathy type II (HMSN II) (HMSN IIc). The present report provides further evidence for heterogeneity among the hereditary motor and sensory neuropathy type II disorders. In one large pedigree with the type IIc disorder, no linkage to DNA markers known to map near the HMSN IA locus on chromosome 17p or the HMSN IB locus on chromosome 1q was demonstrated.

Epidemiology of cervical radiculopathy. A population-based study from Rochester, Minnesota, 1976 through 1990

An epidemiological survey of cervical radiculopathy in Rochester, Minnesota, 1976-90, through the records-linkage system of the Mayo Clinic ascertained 561 patients (332 males and 229 females). Ages ranged from 13 to 91 years; the mean age +/- SD was 47.6 +/- 13.1 years for males and 48.2 +/- 13.8 years for females. A history of physical exertion or trauma preceding the onset of symptoms occurred in only 14.8% of cases. A past history of lumbar radiculopathy was present in 41%. The median duration of symptoms prior to diagnosis was 15 days. A monoradiculopathy involving C7 nerve root was the most frequent, followed by C6. A confirmed disc protrusion was responsible for cervical radiculopathy in 21.9% of patients; 68.4% were related to spondylosis, disc or both. During the median duration of follow-up of 4.9 years, recurrence of the condition occurred in 31.7%, and 26% underwent surgery for cervical radiculopathy. A combination of radicular pain and sensory deficit, and objective muscle weakness were predictors of a decision to operate. At last follow-up 90% of our population-based patients were asymptomatic or only midly incapacitated due to cervical radiculopathy. The average annual age-adjusted incidence rates per 100,000 population for cervical radiculopathy in Rochester were 83.2 for the total, 107.3 for males and 63.5 for females. The age-specific annual incidence rate per 100,000 population reached a peak of 202.9 for the age group 50-54 years.

Botulinum toxin injection for adductor spastic dysphonia: patient self-ratings of voice and phonatory effort after three successive injections

Ten patients (aged 35 to 70 years) with neurologic adductor spastic dysphonia rated themselves on a 7-point scale of severity for degree of voice improvement and physical effort after a series of three injections of botulinum toxin. Symptoms were noticeably reduced 24 and 48 hours after injection; this improvement was followed by considerable fluctuations in voice quality and phonatory effort. With successive injections, patients differed in their post-injection experiences, the time required to reach optimal voice, and the total duration of benefit. The study shows that the course of voice change after botulinum toxin injection is not predictable, uniform, or equal among patients with spastic dysphonia.

Parameters of anorectal and colonic motility in health and in severe constipation

Anorectal function and colonic transit was assessed in 17 severely constipated patients and 15 age-matched controls. The constipated patients were divided into those who had "immobile perineum" (perineal descent < or = 1.0 cm during attempted defecation) and those who had a normal descent (> 1.0 cm) of the perineum. When constipation was accompanied by an immobile perineum, patients had impaired balloon expulsion, impaired and delayed artificial stool expulsion, decreased straightening of the anorectal angle, decreased descent of the pelvic floor with defecation, and prolonged rectosigmoid colon transit compared with the patients with constipation who had a mobile perineum and with normal controls. The mobile-perineum group differed from controls only in colon transit times, having prolonged total colon transit. Anal sphincter resting pressures, immediate artificial stool expulsion, resting anorectal angles, and electromyography of the external anal sphincter and puborectalis did not differentiate the constipated patients from the controls. We concluded that descent of the perineum of < 1 cm was associated with impaired expulsion, an adynamic anorectal angle, and slowed distal colon transit. This simple sign of pelvic floor function distinguished constipated patients with disordered expulsion from constipated patients with normal pelvic floor function. These patients may respond poorly to surgery and conventional management and would therefore be candidates instead for pelvic floor retraining. Accurate characterization and appreciation of pelvic floor dysfunction in patients with severe chronic constipation may improve the selection for and results of surgical and nonsurgical intervention.

The prevalence by staged severity of various types of diabetic neuropathy, retinopathy, and nephropathy in a population-based cohort: the Rochester Diabetic Neuropathy Study

The magnitude of the health problem from diabetic neuropathies remains inadequately estimated due to the lack of prospective population-based studies employing standardized and validated assessments of the type and stage of neuropathy as compared with background frequency. All Rochester, Minnesota, residents with diabetes mellitus on January 1, 1986, were invited to participate in a cross-sectional and longitudinal study of diabetic neuropathies (and also of other microvascular and macrovascular complications). Of 64,573 inhabitants on January 1, 1986 in Rochester, 870 (1.3%) had clinically recognized diabetes mellitus (National Diabetes Data Group criteria), of whom 380 were enrolled in the Rochester Diabetic Neuropathy Study. Of these, 102 (26.8%) had insulin-dependent diabetes mellitus (IDDM), and 278 (73.2%) had non-insulin-dependent diabetes mellitus (NIDDM). Approximately 10% of diabetic patients had neurologic deficits attributable to nondiabetic causes. Sixty-six percent of IDDM patients had some form of neuropathy; the frequencies of individual types were as follows: polyneuropathy, 54%; carpal tunnel syndrome, asymptomatic, 22%, and symptomatic, 11%; visceral autonomic neuropathy, 7%, and other varieties, 3%. Among NIDDM patients, 59% had various neuropathies; the individual percentages were 45%, 29%, 6%, 5%, and 3%. Symptomatic degrees of polyneuropathy occurred in only 15% of IDDM and 13% of NIDDM patients. The more severe stage of polyneuropathy, to the point that patients were unable to walk on their heels and also had distal sensory and autonomic deficits (stage 2b) occurred even less frequently--6% of IDDM and 1% of NIDDM patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemimasticatory spasm: clinical and electrophysiologic observations

Hemimasticatory spasm is a rare disorder of the trigeminal nerve that produces involuntary jaw closure due to paroxysmal unilateral contraction of jaw-closing muscles. We report three patients with this disorder. Electrophysiologic studies demonstrated normal blink and masseter reflexes. The masseter inhibitory reflex was absent during periods of spasm. Needle electromyography demonstrated irregular bursts of motor unit potentials that were identical to the pattern observed in hemifacial spasm. The electrophysiologic findings suggest ectopic excitation of the trigeminal motor root or its nucleus, an abnormality that is analogous to ectopic excitation of the facial nerve in hemifacial spasm. One patient improved temporarily with surgery, one improved while on treatment with carbamazepine, and another responded favorably to botulinum toxin injection.

Effect of BAEP monitoring on hearing preservation during acoustic neuroma resection

We measured the effect of brainstem auditory evoked potential (BAEP) monitoring on hearing preservation in acoustic neuroma resection in 90 consecutive patients with monitoring compared with 90 historical controls matched for tumor size and preoperative hearing status. In small tumors (less than 2 cm), BAEP monitoring was associated with a higher rate of hearing preservation and a greater chance that the hearing preserved was clinically useful. Changes in the BAEP intraoperatively showed a good correlation with postoperative hearing status.

The Rochester Diabetic Neuropathy Study: reassessment of tests and criteria for diagnosis and staged severity

We evaluated the initial assessments of the 380 diabetic patients with and without polyneuropathy in the Rochester Diabetic Neuropathy Study for (1) associations among neuropathy test results, (2) usefulness of different tests for diagnosing and staging polyneuropathy, (3) appropriateness of different minimal criteria for the diagnosis of polyneuropathy, and (4) significant differences in test results with increasing stage of polyneuropathy. Nerve conduction ([NC]; abnormality in two or more nerves) and quantitative autonomic examination ([QAE]; decreased heart-beat response to deep breathing [DB] or the Valsalva maneuver [VAL]) were the most sensitive and objective and were especially suitable for detection of subclinical neuropathy. We propose the following minimal criteria for the diagnosis of diabetic polyneuropathy: greater than or equal to 2 abnormal evaluations (from among neuropathic symptoms, neuropathic deficits, NC, quantitative sensory examination [QSE], and QAE) with one of the two being abnormality of NC or QAE (DB or VAL). Neuropathy Symptom Score, Neuropathy Disability Score, QSE (vibratory or cooling detection threshold), and summated compound muscle action potential of ulnar, peroneal, and tibial nerves were best for judging severity. Inability to walk on heels provided a discrete separation of diabetic patients into those with mild and those with more severe neuropathy--a separation helpful in staging.

Effects of alterations in pulmonary function and sleep variables on survival in patients with amyotrophic lateral sclerosis

Breathing abnormalities and nocturnal hypoventilation occur in patients with amyotrophic lateral sclerosis (ALS). A prospective study was undertaken to determine the relationship of pulmonary function test abnormalities with quality of sleep and survival in 21 patients with ALS. Results of spirometry including determination of maximal respiratory pressures and arterial blood gases were compared with several formal polysomnographic variables and then also with 18-month survival. The patients had mild to moderate pulmonary function deficits, but the quality of sleep was best related to age (mean age, 58.5 years). The results of pulmonary function tests and arterial blood gas measurements did not correlate well with the presence of nocturnal breathing events or survival time, but the maximal inspiratory pressure was 86% sensitive for predicting the presence of a nocturnal oxygen saturation nadir of 80% or less and 100% sensitive for predicting 18-month survival. Although obstructive breathing events occurred, the primary explanation for the decline in nocturnal oxygen saturation was hypoventilation. We conclude that routine pulmonary function tests may be useful for screening for reductions in nocturnal oxygen saturation and also may have prognostic value. Further studies may determine whether treatment of nocturnal hypoventilation will have an effect on survival in patients with ALS who have breathing impairment.

Wohlfart-Kugelberg-Welander syndrome: serum creatine kinase and functional outcome

The medical records of 31 patients (19 male and 12 female) with clinical and electrophysiologic features of Wohlfart-Kugelberg-Welander syndrome were reviewed. The reported age at onset ranged from less than one year to 46 years, and the age at diagnosis ranged from three to 66 years. Proximal muscle weakness, especially of the lower extremities, and muscular atrophy were the predominant clinical features. Elevated serum creatine kinase levels were noted in four female and 12 male patients, and the degree of elevation was higher in the male patients (up to 32 times the upper limit of normal) than in the female patients. On initial evaluation, two patients were wheelchair-bound, whereas the others were ambulatory. On follow-up evaluation three to 32 years later (mean, 15.5 years), 11 patients used wheelchairs, although only three were wheelchair-bound. The disease followed a steady, slowly progressive course. The outcome of ambulatory status did not correlate with the initial creatine kinase determination.

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.

Dynamic joint forces during knee isokinetic exercise

This study analyzed forces in the tibiofemoral and patellofemoral joints during isokinetic exercise using an analytical biomechanical model. The results show that isokinetic exercise can produce large loads on these joints, especially during extension exercises. The tibiofemoral compressive force (4.0 body weight) is approximately equal to that obtained during walking but it occurs at 55 degrees of knee flexion. Anterior shear forces (resisting force to anterior drawer) exist during extension exercise at less than 40 degrees of knee flexion, with a maximum of 0.3 body weight. Posterior shear forces (resisting force to posterior drawer) exist during extension exercise at knee joint angles greater than 40 degrees and during the flexion portion of isokinetic exercise. The maximum posterior shear force is 1.7 body weight. The patellofemoral joint can encounter loads as high as 5.1 body weight which are 10 times higher than during straight leg raises. These results suggest that isokinetic exercise should be used cautiously in patients with knee lesions.

Selective peripheral denervation for torticollis: preliminary results

Herein we report the preliminary results in nine patients who have undergone selective peripheral denervation for spasmodic torticollis and have been followed up for at least 13 months. All patients had improvement immediately after surgical intervention, and the results have been maintained in five patients. In one patient who had recurrent torticollis, a second procedure in conjunction with injection of botulinum toxin has produced substantial improvement; however, follow-up was brief (6 months). No surgical complications occurred. We believe that selective peripheral denervation is safe and that it can benefit patients with torticollis who have not responded to other types of therapy. These favorable results confirm other published reports on the efficacy of selective peripheral denervation. Long-term follow-up, however, is necessary for determining the role of this procedure in the management of torticollis.

Late effects of paralytic poliomyelitis in Olmsted County, Minnesota

We identified a cohort of 300 individuals who had paralytic polio between 1935 and 1955. All lived in Olmsted County, Minnesota. From the 247 survivors, we selected 50 subjects for detailed historical, functional, psychological, clinical, and electrophysiologic evaluation. Sixty-four percent of these 50 survivors complained of new symptoms of muscle pain, fatigue, and weakness after a period of prolonged stability. This led to changes in lifestyle or activity in only 18%. The likelihood of expressing new complaints was not related to present age or interval since polio, and electrophysiologic testing did not distinguish between those with or without new problems. The development of new difficulties in a limb was most strongly predicted by significant paralysis of that limb at the time of the acute illness. Patients with leg weakness were twice as likely to complain of new problems compared to those with arm weakness. Elevated creatine kinase levels were present only in those with new complaints.

Physiological prediction of muscle forces--I. Theoretical formulation

A physiological model for predicting muscle forces is described. Rigid-body mechanics and musculoskeletal physiology are used to describe the dynamics of the segment model and muscle model. Unknown muscle and joint contact forces outnumber the equilibrium equations resulting in an indeterminate problem. Mathematical optimization is utilized to resolve the indeterminacy. The modeling procedure relies entirely on established physiological principles. Data describing the muscle anatomy and body structures are included. A model defining the force-length-velocity-activation relationship of a muscle is adopted. The force a muscle produces is assumed to be proportional to its maximum stress, physiological cross-sectional area, activation, and its functional configurations including the muscle architecture, muscle length, contracting velocity, and passive tension. These factors are incorporated into inequality equations which limit the force for each muscle. Minimal muscular activation is forwarded as the optimization criterion for muscle force determination.

Physiological prediction of muscle forces--II. Application to isokinetic exercise

The successful application of a physiological model of the musculoskeletal system capable of accounting for nonequilibrium dynamic loading and predicting individual muscle forces in the knee is presented. The model incorporates rigid-body mechanics and musculoskeletal physiology. Unknown muscle and joint contact forces outnumber the equilibrium equations resulting in an indeterminant problem. Mathematical optimization is utilized to resolve the indeterminacy. The model is used to estimate individual muscle forces during isokinetic exercise. Five subjects were tested at speeds of 60 degrees/s and 180 degrees/s. A newly proposed optimal criterion, minimizing muscular activation, results in muscle force predictions which have significantly higher correlations with myoelectric activity than other linear and nonlinear optimal criteria. The results demonstrate that properly constrained linear programming methods do not limit the number of active muscles and allow for uniform recruitment of the active muscles.

A comparison of magnetic and electrical stimulation of spinal nerves

The utility of the magnetic coil for stimulation of the cervical spinal nerves was compared to electrical stimulation by a monopolar needle cathode placed onto the spinal lamina in six volunteers. No statistical difference in average amplitudes or areas of evoked CMAPs was found although the size of the magnetic coil evoked potentials was less at C7-8 in several subjects. Electrical stimulation resulted in depolarization at a more proximal site. Electrical stimulation was associated with more discomfort, especially at C5-6. We conclude that electrical stimulation using a monopolar needle as the cathode is the superior technique for the clinical electrophysiologic study of the proximal brachial plexus and cervical spinal nerves.

Trochanteric sciatic neuropathy

A patient with severe weakness, atrophy, and sensory loss of the right leg had a focal right sciatic neuropathy. The sciatic nerve was enlarged at the level of the lesser trochanter, excessively firm, and multistranded; its stimulation threshold was focally increased. Biopsied fascicles had reduplicated perineurial leaflets, many Renaut bodies, and an abnormal unimodal spectrum of small-diameter fibers. We postulate that the lesion was induced by the combination of an underlying prominent lesser trochanter and sitting on hard benches.

Inclusion body myositis. Observations in 40 patients

Inclusion body myositis (IBM) was suspected on light microscopic grounds in 48 of 170 consecutive patients with inflammatory myopathies. One or more vacuoles containing membranous material, groups of atrophic fibres, and an autoaggressive endomysial inflammatory exudate occurred in 100, 96 and 92% of the muscle specimens. All three of these features were present in 88% of the specimens. Electron microscopy confirmed the presence of filamentous inclusions in 40 of 43 patients. The inclusions are typically near vacuoles and a minimum of three vacuolated fibres must be scrutinized to detect them with confidence. There is no electromyographic pattern that can reliably distinguish IBM from other inflammatory myopathies. The typical clinical features in the patients diagnosed by histological criteria as IBM were: insidious onset after age 50 yrs with painless, proximal lower extremity weakness; slow but relentless progression with selectively severe involvement of quadriceps, iliopsoas, tibialis anterior, biceps and triceps muscles; relatively early depression of the knee reflexes; and a normal or mildly elevated serum creatine kinase level. The male: female ratio was 3:1. Distal weakness occurred in about 50%, but only in 35% was it as great or greater than proximal weakness. Significant associated illnesses include other autoimmune disorders (15%), diabetes mellitus (20%), and diffuse peripheral neuropathy (18%). Prednisone treatment at dose levels frequently effective in polymyositis failed to prevent disease progression in those patients observed for 2 or more years. Our findings support the notion that IBM is a distinct entity in which a set of pathological features is associated with a constellation of clinical findings.

Distinction between neoplastic and radiation-induced brachial plexopathy, with emphasis on the role of EMG

The results of clinical, radiologic, and electrophysiologic studies are retrospectively reviewed for 55 patients with neoplastic and 35 patients with radiation-induced brachial plexopathy. The presence or absence of pain as the presenting symptom, temporal profile of the illness, presence of a discrete mass on CT of the plexus, and presence of myokymic discharges on EMG contributed significantly to the prediction of the underlying cause of the brachial plexopathy. The distribution of weakness and the results of nerve conduction studies were of no help in distinguishing neoplastic from radiation-induced brachial plexopathy.

Transdiaphragmatic twitch pressure. Effects of lung volume and chest wall shape

The effect of lung volume and thoracoabdominal shape on the transdiaphragmatic twitch pressure (Pdit) amplitude was evaluated in six volunteers during airway occlusion. Twitch stimulation was applied through fine wire electrodes implanted near both phrenic nerves. Stimulations were tolerated with little discomfort and constant phrenic nerve responses were maintained for hours. At FRC the group mean Pdit was 31.4 cm H2O (range, 19 to 36 cm H2O), and its coefficient of variation ranged between 2 and 5% in individual subjects. At 1 L above FRC, the Pdit decreased a mean of 7.8 cm H2O (range, 2.8 to 11.9 cm H2O). This change was caused primarily by a decrease in esophageal pressure amplitude. The shape of the relaxed chest wall was altered by loading the rib cage with a force of 5 to 9 kg. Load and shape had little effect on Pdit independently of lung volume. Our modified technique of phrenic nerve stimulation through small wire electrodes is ideally suited for longitudinal intervention studies in patients. We conclude that the variability of Pdit with shape is small compared with its expected decrease with lung volume.

Intraoperative electrophysiologic monitoring of laryngeal muscle during thyroid surgery

A technique is described for intraoperative electrophysiologic monitoring of laryngeal muscles. This technique has been used to identify the laryngeal nerves during surgery for recurrent tumors of the thyroid gland, when direct visualization of the nerves is difficult or impossible. Laryngeal muscle electrical activity is monitored with endoscopically placed wire-hook electrodes inserted into the vocal folds bilaterally. Neurotonic discharges are detected when the recurrent laryngeal nerves are manipulated during surgical dissection. Precise localization of the recurrent nerves is possible using a hand-held bipolar stimulator.

The utility of magnetic stimulation for routine peripheral nerve conduction studies

The magnetic stimulator was compared with percutaneous electrical stimulation for activation of the median nerve at the wrist in four volunteers. Magnetic stimulation was unable to achieve supramaximal stimulation without activation of the ulnar nerve. The point of nerve depolarization could not be reliably estimated from the relationship of the stimulator head to the nerve. We conclude that the magnetic stimulator coil is as yet not suitable for routine electrodiagnostic use in the peripheral nervous system.

Lumbar radiculopathy after spinal fusion for scoliosis

In 184 patients with no preoperative neurologic deficit who underwent operation for idiopathic scoliosis, somatosensory evoked potential monitoring was used. Four patients had neurologic deficits postoperatively. Two patients developed mild signs of intraspinal lesions involving upper motor neurons at high lumbar levels that resolved over 3-5 months. These patients and two others developed evidence of unilateral, moderate, lower motor neuron damage that was confirmed on electromyography. No changes in somatosensory evoked potentials occurred in these patients. Lumbar root damage may be difficult to recognize after operation and should be considered in patients with neurologic deficit after scoliosis surgery.