Frank Spaans

Strength training in patients with myotonic dystrophy and hereditary motor and sensory neuropathy: A randomized clinical trial

A randomized clinical trial on the effects of strength training was performed in myotonic dystrophy (MyD) patients and patients with hereditary motor and sensory neuropathy (HMSN). Training and most measurement tools involved the proximal lower extremity muscles. The participants trained 3 times a week for 24 weeks with weights adapted to their force. Strength was evaluated by isokinetically measured knee torque. Fatiguability was assessed by the time an isometric contraction could be sustained. Functional performance was measured by timed motor performance and by questionnaires on functional performance. Serum myoglobin (Mb) levels were determined to detect changes in muscle fiber membrane permeability. The MyD group included 33 participants, and the HMSN group included 29 participants. Within each diagnostic group, patients were individually matched and subsequently randomized for treatment allocation. In the MyD patients, none of the measurement techniques showed any training effect. Neither were there signs of deterioration caused by the training. In the HMSN group, knee torques increased. Timed motor performance did not change, although the questionnaires showed an improvement on items related to upper-leg function. Mb levels did not change significantly as a result of the training. In conclusion, the MyD group showed neither positive nor negative effects of the training protocol, whereas the training produced a moderate increase in strength and leg-related functional performance in the HMSN group.

Small fiber neuropathy: a common and important clinical disorder

Small fiber neuropathy (SFN) is a neuropathy selectively involving small diameter myelinated and unmyelinated nerve fibers. Interest in this disorder has considerably increased during the past few years. It is often idiopathic and typically presents with peripheral pain and/or symptoms of autonomic dysfunction. Diagnosis is made on the basis of the clinical features, normal nerve conduction studies (NCS) and abnormal specialized tests of small nerve fibers. Among others, these tests include assessment of epidermal nerve fiber density, temperature sensation tests for sensory fibers and sudomotor and cardiovagal testing (QSART) for autonomic fibers. Unless an underlying disease is identified, treatment is usually symptomatic and directed towards alleviation of neuropathic pain.

Effects and side effects of a percutaneous thermal lesion of the dorsal root ganglion in patients with cervical pain syndrome

&NA; Twenty consecutive patients with intractable chronic pain in the cervical region were treated with a radiofrequency lesion of the dorsal root ganglion on level C4, C5 or C6. Electromyography (EMG) and sensory evoked potentials (SEP) were recorded before and 3 weeks after the radiofrequency lesion. Side effects were studied 3 weeks, 6 weeks and 3 months after the procedure. Pain scores were evaluated on Numeric Rating Scales (NRS) before and 6 weeks after treatment. The patient was interviewed 3, 6 and 9 months after the radiofrequency lesion. The most common side effect was burning pain in the dermatome of the treated nerve root. Hyposensibility in the dermatome was noticed in 35% of patients. Except in 1 patient, these side effects had disappeared 6 weeks after treatment. The EMG showed no signs of denervation. One SEP recording remained abnormal after treatment. There was initial pain relief in 75% of patients after 3 months and in 50% of the patients after 6 months. In conclusion, this study did not reveal any signs of motor denervation after a percutaneous partial rhizotomy. There were no long‐term signs of deafferentation. Initial pain relief was found in 75% of patients, but there was a marked tendency for pain to recur in a period from 3 to 9 months after treatment.

Progressive resistance training in neuromuscular patients. Effects on force and surface EMG

In a randomized clinical trial the efficacy of strength training was studied in patients with myotonic dystrophy (n = 33) and in patients with Charcot-Marie-Tooth disease (n = 29). Measurements were performed at the start and after 8, 16 and 24 weeks of progressive resistance training. Surface electromyography (SEMG) of proximal leg muscles was recorded during isometric knee extension at maximum voluntary contraction (MVC) and at 20, 40, 60 and 80% of MVC. Changes in MVC, maximum electrical activity and torque-EMG ratios (TER) were calculated. Fatigue was studied by determining the changes in endurance and in the decline of the median frequency (Fmed) of the SEMG during a sustained contraction at 80% MVC. These parameters showed no significant changes after the training in either of the diagnostic groups. Only the Charcot-Marie-Tooth training group showed a gradual significant increase in mean MVC over the whole training period (21%). After 24 weeks, the increase in mean RMS was similar (25%), but this was mainly due to a sharp rise during the first 8 weeks of training (20%). The findings indicate that the initial strength increase was due to a neural factor, while the subsequent increase was mainly due to muscle hypertrophy.

Abnormal warm and cold sensation thresholds suggestive of small-fibre neuropathy in sarcoidosis.

OBJECTIVE A substantial number of sarcoidosis patients report apparently non-specific symptoms such as pain, for which no organic substrate has yet been found. Recently we observed symptoms suggestive of small-fibre neuropathy in a group of sarcoidosis patients. The aim of the present study was to verify this observation using various electrophysiological tests. METHODS In 74 sarcoidosis patients complaining of symptoms suggestive of small-fibre neuropathy, thresholds for warm (WS) and cold sensation (CS) as well as for heat pain were determined at the thenar eminence and the foot dorsum. Furthermore, sympathetic skin responses (SSR), nerve conduction studies and concentric needle electromyography were performed. In 31 patients, cardiovascular autonomic testing was carried out. RESULTS Thermal threshold testing (TTT) revealed abnormalities in 51 of the 74 patients. Abnormalities showed an asymmetrical distribution. WS was affected more often than CS and feet more often than hands. Nerve conduction studies in the legs showed slightly abnormal results in 6 patients; all of these had abnormal TTT results. The SSR was absent at the foot in 7 patients. Cardiovascular autonomic testing was abnormal in only a single patient. CONCLUSIONS In a subgroup of sarcoidosis patients we found TTT abnormalities suggestive of small-fibre neuropathy. SSR and cardiovascular autonomic testing appeared to be of little diagnostic value. Small-fibre neuropathy may be the cause of a number of hitherto unexplained symptoms in sarcoidosis.

Impaired balance control in paraplegic subjects.

Postural muscle use during sitting balance control was studied in persons with a complete thoracic spinal cord injury (SCI). It was hypothesized that these subjects use non-postural muscles such as the latissimus dorsi (LD) and trapezius pars ascendens (TPA) to restore sitting balance, whereas non-SCI subjects primarily use their erector spinae (ES). This adaptive postural strategy in SCI subjects presupposes stabilizing effects of the scapular protractors, such as the pectoralis major (PM) and the serratus anterior (SA), on the shoulder girdle. Sitting balance was perturbed systematically in three groups of either low thoracic SCI, high thoracic SCI or non-SCI participants. Centre of pressure changes and activity of the LD, TPA, PM, SA, ES and oblique abdominal (OA) muscles were measured during task execution. Because non-SCI subjects differ from SCI subjects in their ability to tilt their pelvis during sitting, the correlation between pelvic movement and postural changes during task execution was also investigated. Results indicate that high thoracic SCI subjects use their LD, TPA, PM, SA and high thoracic part of the ES more in situations of similarly perturbed sitting balance than non-SCI subjects. Differences are smaller in the low thoracic SCI group. A kinematic concept combining alternative postural muscle activity and altered movement in thoracic SCI subjects is discussed.

Interobserver variation in the interpretation of SSEPs in anoxic–ischaemic coma

OBJECTIVE To study interobserver variation in the interpretation of median nerve SSEPs in patients with anoxic-ischaemic coma. METHODS SSEPs of 56 consecutive patients with anoxic-ischaemic coma were interpreted independently by 5 experienced clinical neurophysiologists using guidelines derived from a pilot study. Interobserver agreement was expressed as kappa coefficients. RESULTS Kappa ranged from 0.20 to 0.65 (mean 0.52, SD 0.14). Disagreement was related with noise level and failure to adhere strictly to the guidelines in 15 cases. The presence or absence of N13 and cortical peaks caused disagreement in 5 cases each. For recordings with a noise level of 0.25 microV or more, mean kappa was 0.34; for recordings with a noise level below 0.25 microV mean kappa was 0.74. CONCLUSIONS Interobserver agreement for SSEPs in anoxic-ischaemic coma was only moderate. Since the noise level strongly influenced interobserver variation, utmost attention should be given to its reduction. If an artefact level over 0.25 microV remains, absence of N20 cannot be judged with sufficient certainty and the SSEP should be repeated at a later stage. SIGNIFICANCE Because of its moderate interobserver agreement, great care has to be given to accurate recording and interpretation of SSEPs before using the recordings for non-treatment decisions.

Surface EMG of proximal leg muscles in neuromuscular patients and in healthy controls. Relations to force and fatigue

In an effort to find parameters to evaluate patients with neuromuscular disorders, surface electromyography (SEMG) of proximal leg muscles was performed in 33 patients with myotonic dystrophy (MyD), 29 patients with Charcot-Marie-Tooth (CMT) disease and 20 healthy controls. The root mean square (RMS) of the SEMG amplitude (microV) was calculated at different torque levels. Endurance (seconds) and median frequency (Fmed) of the SEMG power spectrum, used as parameters of fatigue, were determined at 80% of MVC. Maximum voluntary contraction (MVC) was found to be decreased in patients; the ratio between RMS values of antagonists and agonists was increased and torque-EMG ratios (Nm/microV) were decreased. These differences with respect to controls were more pronounced in MyD than in CMT. The initial Fmed value was lowest in CMT. The greatest decrease in Fmed was found in MyD. SEMG data in relation to force have not been determined before in groups of MyD or CMT patients. In both disorders, parameters differed from controls, which means that adding SEMG to strength measurements could be useful in studying the progress of the disorder and the effects of interventions.

Limb-girdle muscular dystrophy in the Netherlands: Gene defect identified in half the families

Pheno- and genotype correlation is attempted in a Dutch cross-sectional study on limb- girdle muscular dystrophy. Sarcoglycans, caveolin-3, calpain-3, and dysferlin were analyzed on muscle tissue. Mutation analysis of the calpain-3, caveolin-3, and fukutin-related protein gene was executed in successive order for all samples. In 51% of all families a classifying diagnosis was made. Several new mutations in LGMD2A, B, and C patients have been found in this population.

Quadriceps strength and timed motor performances in myotonic dystrophy, Charcot–Marie–Tooth disease, and healthy subjects

Background and purpose: The leading hypothesis was that a relation exists between muscular strength and functional abilities. Therefore a study was undertaken to quantify such a relationship in a population of subjects with different muscular strengths. This population consisted of healthy subjects and subjects with slowly progressive neuromuscular disorders. Methods: The study included 33 patients with myotonic dystrophy, 29 patients with Charcot–Marie–Tooth disease and 20 healthy subjects. Isokinetic and isometric knee torques were measured on an isokinetic dynamometer at various velocities. The following activities were timed: descending and ascending stairs, rising from a chair, rising from supine, walking at natural speed and walking at maximum speed. Results: The population covered a wide range of the variables: whereas the healthy subjects performed best (i.e. had the highest knee torques and performed the activities most quickly), the myotonic dystrophy group included the subjects with the lowest knee torques. The natural logarithms (ln) of isokinetic extension torque at the highest velocity (120°/s) and those of the time taken to perform the described activities showed the highest levels of correlation. It was found that after correction for age and weight, 56% (walking at natural speed) to 73% (descending stairs) of the variance in the ln of the time taken could be attributed to the variance in the ln of the torques. Conclusion and discussion: A strong relation between quadriceps strength and timed motor performances were demonstrated. The impact of strength reduction on time taken was most obvious in subjects with considerably decreased strength. Therefore, it is feasible to try to influence muscle strength in patients with relevant strength reduction in order to achieve better functional ability.