Jack H. Petajan

The natural history of amyotrophic lateral sclerosis

Using 42 strength and functional assessments recorded monthly, the natural history of amyotrophic lateral sclerosis (ALS) is described in 167 patients (98 men, 67 women) followed in five medical centers in the western United States. The mean age at onset was 57.4 years, and symptoms were present for 2.64 years before study entry. Although there was a highly variable rate of decline within the group of patients, there were no differences in rate of decline by age or gender. Older patients and women were weaker on entry. Forty-eight patients died during the study. The median survival was 4.0 years for the study cohort but 2.1 years for newly diagnosed cases. Decline in pulmonary function most closely correlated with death. Our results emphasize the importance of considering clinical variability in planning clinical trials. One possible strategy is to identify and stratify patients by rate of decline in pulmonary function since prospectively identifying homogeneous subgroups allows investigators to substantially reduce sample size in therapeutic trials.

Recommendations for Physical Activity in Patients with Multiple Sclerosis

For many years, patients with multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system, have been advised to avoid exercise. MS is believed to be autoimmune in origin, mediated by activated T cells which penetrate the blood-brain barrier and attack myelin. The pathophysiology, with respect to function is an impairment of saltatory conduction, specifically, slowing of conduction speed and/or conduction block. Symptoms can temporarily worsen on exposure to heat or during physical exercise.Exercise programmes must be designed to activate working muscles but avoid overload that results in conduction block. Fatigue, often severe, affects about 85% of MS patients and, along with motor and sensory symptoms, results in decreased mobility and reduced quality of life. Physical activity and recreation are reduced in patients with MS. Before developing recommendations, physical activity patterns and the physical effects of MS should be assessed in individual patients. Patients may then be functionally classified. Physical activity can also be classified in a pyramid structure, with the most basic functions forming the base and the most integrated functions on top. The muscular fitness pyramid progresses through passive range of motion, active resistive, specific strengthening and integrated strength exercises. Overall physical activity may be increased according to functional level by performing activities of daily living, incorporating inefficiencies into daily living, pursuing more active recreation and eventually developing a structured exercise programme.The importance of the proper exercise environment, balance and coordination issues and factors related to adherence are discussed.

Phase III randomized trial of gabapentin in patients with amyotrophic lateral sclerosis

Background: Preclinical and clinical studies of gabapentin in patients with ALS led the authors to undertake a phase III randomized clinical trial. Methods: Patients were randomly assigned, in a double-blinded fashion, to receive oral gabapentin 3,600 mg or placebo daily for 9 months. The primary outcome measure was the average rate of decline in isometric arm muscle strength for those with two or more evaluations. Results: Two hundred four patients enrolled, 196 had two or more evaluations, and 128 patients completed the study. The mean rate of decline of the arm muscle strength was not significantly different between the groups. Moreover, there was no beneficial effect upon the rate of decline of other secondary measures (vital capacity, survival, ALS functional rating scale, timed walking) nor was there any symptomatic benefit. In fact, analysis of the combined data from the phase II and III trials revealed a significantly more rapid decline of forced vital capacity in patients treated with gabapentin. Conclusion: These data provide no evidence of a beneficial effect of gabapentin on disease progression or symptoms in patients with ALS.

Prolonged paralysis after treatment with neuromuscular junction blocking agents

ObjectivesPrevious reports have described prolonged paralysis after treatment with neuromuscular junction blocking agents in critically ill patients. The purpose of this study was to further describe a group of patients who developed prolonged weakness after treatment with these agents. DesignClinical information, electrodiagnostic and muscle pathology results are described in this group of patients. Clinical information includes diagnoses, dosage of neuromuscular junction blocker, other medications affecting the neuromuscular system, and neuromuscular examination and clinical course. SettingAll patients were seen in the ICUs of three local hospitals. PatientsIncluded were critically ill patients with a variety of diagnoses, all of whom developed severe weakness after discontinuation of neuromuscular junction blocking agents. InterventionsElectrodiagnostic studies and muscle biopsies were performed on several of the patients. Measurements and Main ResultsAll patients had pronounced weakness without sensory loss. Electrodiagnostic and muscle pathology findings were consistent with failed neuromuscular transmission. Although many patients had disorders or were taking medications that can injure the neuromuscular system, no disorder or medication was common to all. Recovery of strength often took several months and most patients were slow to wean from mechanical ventilator support. ConclusionsAlthough alternative explanations cannot be excluded with certainty, the use of neuromuscular junction blocking agents may lead to neurogenic atrophy and care must be taken when using them.

Placebo-controlled trial of gabapentin in patients with amyotrophic lateral sclerosis

We designed a phase II trial to evaluate the efficacy of gabapentin in slowing the rate of decline in muscle strength of patients with amyotrophic lateral sclerosis (ALS) and to assess safety and tolerability.Gabapentin (800 mg) or placebo was administered t.i.d. in a randomized, double-blinded, placebo-controlled, trial for 6 months. We enrolled 152 patients at eight sites in the United States. The primary outcome measure was the slope of the arm megascore, the average maximum voluntary isometric strength from eight arm muscles standardized against a reference ALS population. A secondary outcome measure was forced vital capacity. Slopes of arm megascores for patients on gabapentin were compared with slopes of those taking placebo using a two-way ANOVA. We observed a nonstatistically significant trend (p = 0.057-0.08) toward slower decline of arm strength in patients taking gabapentin compared with those taking placebo (mean difference 24%, median 37%). We observed no treatment effect on forced vital capacity. Gabapentin was well tolerated by patients with ALS. These results suggest that further studies of gabapentin in ALS are warranted. NEUROLOGY 1996;47: 1383-1388

Correlating phenotype and genotype in the periodic paralyses.

Background: Periodic paralyses and paramyotonia congenita are rare disorders causing disabling weakness and myotonia. Mutations in sodium, calcium, and potassium channels have been recognized as causing disease. Objective: To analyze the clinical phenotype of patients with and without discernible genotype and to identify other mutations in ion channel genes associated with disease. Methods: The authors have reviewed clinical data in patients with a diagnosis of hypokalemic periodic paralysis (56 kindreds, 71 patients), hyperkalemic periodic paralysis (47 kindreds, 99 patients), and paramyotonia congenita (24 kindreds, 56 patients). For those patients without one of the classically known mutations, the authors analyzed the entire coding region of the SCN4A, KCNE3, and KCNJ2 genes and portions of the coding region of the CACNA1S gene in order to identify new mutations. Results: Mutations were identified in approximately two thirds of kindreds with periodic paralysis or paramyotonia congenita. The authors found differences between the disorders and between those with and without identified mutations in terms of age at onset, frequency of attacks, duration of attacks, fixed proximal weakness, precipitants of attacks, myotonia, electrophysiologic studies, serum potassium levels, muscle biopsy, response to potassium administration, and response to treatment with acetazolamide. Conclusions: Hypokalemic periodic paralysis, hyperkalemic periodic paralysis, and paramyotonia congenita may be distinguished based on clinical data. This series of 226 patients (127 kindreds) confirms some clinical features of this disorder with notable exceptions: In this series, patients without mutations had a less typical clinical presentation including an older age at onset, no changes in diet as a precipitant, and absence of vacuolar myopathy on muscle biopsy.

Effect of precooling on physical performance in multiple sclerosis

Many individuals with MS experience heat sensitivity that may be associated with transient increases in the frequency of clinical signs and symptoms. Although physical activity may be beneficial for those with MS, induced thermal loads may preclude participation in exercise and other daily activities. This project was designed to evaluate the effects of precooling on physical function. Six thermosensitive MS patients were studied. Participants performed a graded exercise test to determine maximal oxygen uptake (VO2max) on a combined arm-leg ergometer. Thermal load was induced by 30 min of exercise under noncooled and precooled conditions at a workrate corresponding to 60% VO2max. Precooling consisted of 30 min lower body immersion in 16-178C water. Fatigue and 25-ft walk performance were assessed before, immediately after, and 30 min following exercise. No treatment differences in VO2 were observed. Rectal temperature, heart rate, and rating of perceived exertion (RPE) were significantly lower during the precooled exercise trial compared to the noncooled trial. Immediately following exercise, 25-ft walk performance and fatigue scores showed significantly greater deterioration in the noncooled condition. Precooling was effective in preventing gains in core temperature with physical work and may allow heat-sensitive individuals with MS to exercise with greater physical comfort.

Toxicity and tolerability of recombinant human ciliary neurotrophic factor in patients with amyotrophic lateral sclerosis.

We examined the toxicity of both single and multiple subcutaneous injections of recombinant human ciliary neurotrophic factor (rhCNTF) in 72 patients with ALS, in doses ranging from 2 to 100 micro gram/kg.Adverse events were generally dose related and ranged from mild to severe. The tolerability of daily subcutaneous rhCNTF was equivalent to placebo at doses <or=to 5 micro gram/kg/day. At higher doses, anorexia, weight loss, reactivation of herpes simplex virus (HSV1) labialis/stomatitis, cough, and increased oral secretions occurred. NEUROLOGY 1996;47: 1329-1331

Plasmapheresis in multiple sclerosis Preliminary findings

In seven of eight patients with progressive multiple sclerosis subjected to long-term plasmapheresis in combination with azathioprine and pulsed prednisone therapy, we found modest improvement of neurologic function. There was no change in auditory and visual evoked responses or serum demyelinating activity. In six of seven patients, cerebrospinal fluid IgG content decreased. Three additional patients in acute, severe exacerbation refractory to prednisone therapy made a substantial recovery, which commenced with plasmapheresis therapy. In two of them, the onset of clinical improvement after plasmapheresis was corroborated by decreased latency or increased amplitude of somatosensory evoked potentials. These results suggest that blood-borne factors, possibly autoantibodies, may play a role in the pathogenesis of the disease. The lesions may be at least partially reversible with plasmapheresis therapy, but a controlled trial is necessary to confirm these preliminary findings.

Changes in excitability of motor cortical circuitry in primary restless legs syndrome

Objective: To investigate the excitability of segmental and suprasegmental systems in patients with primary restless legs syndrome (pRLS) by measuring the cortical silent period (C-SP) and the peripheral silent period (P-SP). Background: There is some evidence that RLS may be the motor manifestation of normal CNS periodicity that becomes disinhibited under certain conditions. The mechanism of this disinhibition is unclear. Design/Methods: Ten patients with pRLS and 10 normal age-matched subjects were studied. The mixed nerve P-SP produced by electrical stimulation of the median and common peroneal nerves was recorded during maximal contraction of the abductor pollicis brevis (APB) and tibialis anterior (TA) muscles. The C-SP produced by a single magnetic shock to motor cortex at 150% of resting threshold was also measured during maximal contraction of the APB and TA muscles. The average of 5 to 10 trials at each site was obtained and compared using Student’s t-test. Results: Resting central motor threshold was not significantly different between pRLS patients and the control group. The average duration of the C-SP was shorter in the APB (74.5 ± 37.7 versus 129.56 ± 35.95 msec, p < 0.05) and TA (66.81 ± 25.63 versus 136.1 ± 40.35 msec, p < 0.05) in patients with pRLS. The P-SP duration, however, was not significantly different between two groups in either limb. Conclusion: The supraspinal inhibitory system is impaired in pRLS.