Quantification of Uhthoff's phenomenon in multiple sclerosis: a magnetic stimulation study

OBJECTIVE

To quantify temperature induced changes (=Uhthoff phenomenon) in central motor conduction and their relation to clinical motor deficits in 20 multiple sclerosis (MS) patients.

METHODS

Self-assessment of vulnerability to temperature and clinical examination were performed. We used motor evoked potentials to measure central motor conduction time (CMCT) and applied the triple stimulation technique (TST) to assess conduction failure. The TST allows an accurate quantification of the proportion of conducting central motor neurons, expressed by the TST amplitude ratio (TST-AR).

RESULTS

Temperature induced changes of TST-AR were significantly more marked in patients with prolonged CMCT (P=0.037). There was a significant linear correlation between changes of TST-AR and walking velocity (P=0.0002). Relationships were found between pronounced subjective vulnerability to temperature and (i) abnormal CMCT (P=0.02), (ii) temperature induced changes in TST-AR (P=0.04) and (iii) temperature induced changes in walking velocity (P=0.04). CMCT remained virtually unchanged by temperature modification.

CONCLUSIONS

Uhthoff phenomena in the motor system are due to varying degrees of conduction block and associated with prolonged CMCT. In contrast to conduction block, CMCT is not importantly affected by temperature.

SIGNIFICANCE

This is the first study quantifying the Uhthoff phenomenon in the pyramidal tract of MS patients. The results suggest that patients with central conduction slowing are particularly vulnerable to develop temperature-dependent central motor conduction blocks.

Fatigue in MS is related to sympathetic vasomotor dysfunction

The authors studied standard autonomic function tests and measures of heart rate variability in 60 patients with multiple sclerosis (MS) and correlated results with the Fatigue Severity Scale and the Modified Fatigue Impact Scale. The authors found that autonomic responses correlated with fatigue resembling a hypoadrenergic orthostatic response, possibly due to a sympathetic vasomotor lesion with intact vagal heart control. Treatments to control sympathetic dysfunction for MS-associated fatigue deserve further study.

Effects of a short-term exercise training program on aerobic fitness, fatigue, health perception and activity level of subjects with multiple sclerosis

Multiple sclerosis (MS) patients of an inpatient rehabilitation program have been randomly assigned to an exercise training (MS-ET) or nontraining group (MS-NI). Before and after 4 weeks of aerobic exercise training, a graded maximal exercise test with measurement of gas exchange and a lung function test was administered to all 26 patients fulfilling the inclusion criteria. Activity level, fatigue and health perception were measured by means of questionnaires. Twenty-six healthy persons served as control group and were matched in respect of age, gender and activity level. Training intervention consisted of 5x30 min sessions per week of bicycle exercise with individualised intensity. Compared with baseline, the MS training group demonstrated a significant rightward placement of the aerobic threshold (AT) (VO2+13%; work rate [WR])+11%), an improvement of health perception (vitality+46%; social interaction+36%), an increase of activity level (+17%) and a tendency to less fatigue. No changes were observed for the MS-NI group and the control groups. Maximal aerobic capacity and lung function were not changed by either training or nontraining in all four groups. Overall compliance to the training program was quite low (65%), whereas incidence of symptom exacerbation by physical activity has been lower than expected (6%).

Impact of neurorehabilitation on disability in patients with acutely and chronically disabling diseases of the nervous system measured by the Extended Barthel Index

To study the impact of rehabilitation on disability in an unselected patient group with acutely and chronically disabling neurologic diseases, the Extended Barthel Index (EBI) was determined at the beginning and at the end of the rehabilitation stay in all patients admitted to our Neurorehabilitation Centre in Valens, Switzerland. Patients who reached the highest possible EBI score at entry ("ceiling effect"), with a short stay (<1 week), or with a deterioration due to other medical complications were excluded. Finally EBI data of 743 patients could be analyzed. The mean EBI at entry was 45 and 51 at discharge. The mean increase of the EBI score per week was 1.1 (SD, 1.7). The change of the EBI score was analyzed independently in patients with acute neurologic diseases admitted in the postacute phase (acute group) and patients with chronically disabling neurologic diseases (chronic group). As expected, the increase of the EBI score was higher in the acute group than in the chronic group; 80.8% of the acute group patients and 42.5% of the chronic group patients showed an increase of the EBI score at discharge. Both groups showed a significant EBI gain with a marked shift to higher EBI scores at discharge. The mean gain per week was 1.6 in the acute group and 0.5 in the chronic group, respectively. Analysis of EBI changes considering the different underlying diseases showed the highest increase in patients with stroke and traumatic brain injury.

Cognitive and affective disturbances in multiple sclerosis

The emotional and relationship problems associated with MS have not always been fully appreciated by the medical profession, which has tended to concentrate on the physical aspects of this disease. Yet the psychological problems of MS often cause more suffering than physical effects.

Neuroscience and clinical practice: a personal postscript

For such complex endeavours as understanding functions of the nervous system and treating patients with impairments of such functions, a continuous exchange of ideas in mutually understandable language is needed between researchers and clinicians. Neither of them is capable in the long run of doing justice to the scientific aspects of neuroscience and neurology and to the expectation of the patients on his or her own. It should become possible to bridge the gap between caring for patients and a scientific understanding of the mechanisms by which certain therapies work and the measurement of performance and outcome which is important for the credibility of interventions. The scientific approach to neurology has led to remarkable improvements in understanding some of the disease processes and to some valuable new therapies. There is no fundamental contradiction, however, between this approach and the pastoral aspects of medical care.

Neurorehabilitation: a bridge between basic science and clinical practice

A true paradigm shift or revolution of thinking is taking place in the field of neurology. Earlier, it was regarded as the science of exact diagnosis of incurable illnesses, according to the resigned dogma that damage to the central nervous system could not be repaired: "Once development is complete, the sources of growth and regeneration of axons and dendrites are irretrievably lost. In the adult brain the nerve paths are fixed and immutable: everything can die, nothing can be regenerated" (Cajal, 1928). Even then one could have countered this with what holds today: "Rehabilitation does not take place in the test tube!", and one would have been supported only a short time later by a most authoritative source, if one had read and quoted what the professor of neurology and neurosurgery in Breslau, Otfried Foerster, wrote in a 100-page article about therapeutic exercises that appeared in the Handbuch der Neurologie. From his introduction, only three sentences are quoted, which illustrate his opinion of the importance of therapeutic exercises and are closer to our views of brain functions today (Foerster, 1936): There is no doubt that most motor disturbances caused by lesions of the nervous system are more or less completely compensated as a result of a tendency inherent to the organism to carry out as expediently as possible the tasks of which it is capable under normal circumstances, using all the forces still available to it with the remaining undamaged parts of the nervous system, even following injury to its substance. This happens spontaneously, when neither a reversal of the noxa nor a regeneration of the destroyed tissue is possible, simply by means of a reorganization of the remaining parts of the nervous system, which is not a machine composed of individual parts that stands still when one part fails; rather, it possesses an admirable plasticity and exhibits an astonishingly extensive adaptability, not only to changed external conditions but also to disruptions of its own substance. Therapeutic exercises influence the course of spontaneous restoration; they support it, strengthen it. Not infrequently, in fact, they actually set it in motion when the forces essential to restoration lie fallow and are not deployed by the organism.

Increased endothelin-1 plasma levels in patients with multiple sclerosis

OBJECTIVE

We tested the hypothesis that the plasma level of endothelin-1 (ET-1) is increased in patients with multiple sclerosis (MS). The peptide ET-1 is one of the most potent known vasoconstrictors. An increased level of endothelin could explain some of the vascular symptoms of these patients.

MATERIALS AND METHODS

A specific radioimmunoassay was used to determine ET-1 plasma levels. Twenty patients with MS were compared to 20 age- and sex-pair-matched healthy subjects.

RESULTS

The plasma ET-1 levels were, on average, 224% higher in the patients with MS than in the controls (p < 0.005). The mean ET-1 levels (mean +/- standard deviation [SD]) were 3.5 +/- 0.83 pg/mL (min 2.13, max 5.37 pg/mL) in patients with MS and 1.56 +/- 0.3 pg/mL (min 0.9, max 2.13 pg/mL) in healthy volunteers. Neither the different forms nor stages of MS had an influence on the results. The ET-1 level was also not correlated with the duration of the disease.

CONCLUSIONS

The plasma ET-1 level is markedly and significantly increased in patients with MS. Neither the cause of such an increase nor the pathogenetic role is known.

Multiple sclerosis and infectious childhood diseases

To examine a possible relationship between infectious diseases and multiple sclerosis (MS) an enquiry was carried out among 606 MS patients in Switzerland. The data concerning their infectious childhood diseases were compared with epidemiological data for the normal Swiss population obtained from the Swiss Federal Health Office and from the Institute of Medical Statistics. The mean age of the MS patients was 50.7 years and the mean age at onset of multiple sclerosis was 33.8 years, significantly earlier in women (33.2 years) than in men (35.4 years, p < 0.05). In 18.8% multiple members of the family were affected. In comparison with persons of the control population, MS patients had measles infection at a later age (6.4 vs. 7.5 years). The curve of the age at which several infectious childhood diseases occurred was shifted to higher ages for MS patients (p < 0.005) compared to normal controls for mumps (80.2% for MS vs. 64.1% for controls in the age group 5-14 years), rubella (64.3% for MS vs. 48.4% for controls in the age group 5-14 years) and varicella (81.9% for MS vs. 39.0% for controls in the age group 5-19 years). For pertussis, however, there were more cases among those who later developed MS in the age group 1-9 years, which was earlier than in controls (86.0 vs. 56.7%). These results are compatible with the hypothesis that the risk of developing multiple sclerosis may be associated with acquiring certain infectious childhood diseases at a later stage in comparison to normal controls.

Reversible neuropsychological deficits after mild traumatic brain injury

OBJECTIVES

To determine the influence of motivation on performance in a divided attention test of patients after mild traumatic brain injury (MBI).

METHODS

Comparison of the performance of 12 patients with MBI with 10 patients with severe brain injury (SBI) and 11 healthy controls in a computer supported divided attention task before (T1) and after (T2) verbal motivation.

RESULTS

At T1, the MBI group performed the same as the SBI group but significantly worse than the controls in all variables. At T2, the MBI group performed worse than the controls at T2 but the results were equal to the results of the controls at T1 and significantly better than the SBI group at T1 or T2. At T2 the MBI group performed at the level of published norms for the rest.

CONCLUSION

Before verbal motivation the MBI group's results in the divided attention task were comparable with those from patients with severe brain injury. They failed to exploit their performance potential when it depended on self motivation but were able to perform at the level of the control group when external motivation was applied.

Constantin von Monakow's formative years in Pfäfers

Constantin von Monakow was the first professor of neurology in Switzerland and founder of the Swiss Neurological Society and of the Swiss Archives of Neurology and Psychiatry. He gained worldwide reputation as a neuroscientist mainly through his monumental work on neuropathology and cortical localization. His concept of diaschisis has been verified only in recent years by modern network concepts and imaging techniques. The basis of his work was developed with ingenious animal experiments and careful clinico-pathological comparisons during his early years, which he spent as assistant physician in the psychiatric clinic at St. Pirminsberg in Pfäfers, Canton St. Gallen, Switzerland from 1878 to 1885.

Detection of anterior horn lesions by MRI in central European tick-borne encephalomyelitis

We report a case of central European tick-borne encephalitis with cervical myelitis presenting clinically as a lower motor neuron syndrome of the upper limbs with proximal asymmetrical pareses and atrophies. There were no sensory deficits nor signs of lesions of the spinal pathways or signs of encephalitis or meningitis. The affected motor fibers of the upper limbs were electrically inexcitable, but sensory findings were normal. Electromyography of the paralyzed muscles revealed pathological denervation activity without voluntary activation. The initial magnetic resonance imaging (MRI) showed a large hyperdense lesion in the anterior part of the cervical cord from C3 to T1. Despite the fact that MRI changes disappeared completely within 6 weeks the patient showed only little improvement in the paralyzed muscles after 6 months. To our knowledge, these MRI changes in patients with tick-borne encephalitis, consistent with an isolated anterior horn lesion, have never been reported previously. The course may have been aggravated by an initial antibiotic treatment with cephalosporins.

[How is the brain tuned?]

The brain is the organ which organizes the interaction between the organism and the environment. On the afferent side perceptive channels provide information from the outer and inner worlds. On the efferent side there is only the muscle system with its governing neural organisation. The brain as a tool or instrument can be put in tune like an instrument of music, in the best way by harmonizing inner intentions and desires with external demand.

[Leg pain--the contribution of the neurologist]

Pain syndromes in the lower limbs are a particular challenge for the clinical neurologist. Pain may be due to various disorders of the central and peripheral nervous system or muscles of different etiologies. There is a continuum from slightly unpleasant sensory disturbances to nociception. Differential diagnosis must be sought according to topological and pathophysiological interpretation of the clinical findings. This will determine the necessary diagnostic requirements and therapeutic procedures. Within the central nervous system lesions of the nociceptive projections of the spinal cord or brain may lead to pain in the lower limbs. Furthermore, different pathologies of the peripheral nervous system (root, plexus, peripheral nerve) or muscles can cause pain. Finally, pain syndromes are known in clinical syndromes with disturbances of the muscle tone (extrapyramidal syndromes, spasticity) and secondary to postural problems in patients with muscular dysbalance due to paralysis.

[National Research Program NFP 38: "Diseases of the nervous system"]

The aim of Programme 38 of the Swiss National Research Foundation is to enhance collaboration between basic science and clinical application, as related to diseases of the nervous system, over a 5-year period. The 15 ongoing projects are described. They are mainly concerned with mechanisms of pathogenesis and recovery of function, and ways of modifying them therapeutically after traumatic lesions or various diseases of the nervous system such as stroke, Parkinson's disease, Alzheimer's dementia, depression, meningitis, HMSN etc.

Spasticity, ataxia and fatigue in multiple sclerosis

Multiple sclerosis frequently results in a wide range of symptoms which often coexist, creating a complex pattern of disability. Chief among these symptoms, both in relation to their frequency and their impact on the patient, are spasticity, ataxia and fatigue. This chapter discusses the pathological basis and current treatment of these symptoms and stresses the importance of a multidisciplinary approach to their management, producing a comprehensive care plan which incorporates these and any other coexisting problems.

[Prognosis in multiple sclerosis]

Prognosis of the natural course of multiple sclerosis is most often measured on Kurtzke's "expanded disability status scale" (EDSS), a non-linear scale over 20 steps, heavily weighted on mobility. Optic neuritis and sensory disturbances as initial symptoms, lower age at onset of the disease, female sex and a longer interval between relapses are indicators of a more favorable prognosis. As a rule, disability as measured on this scale 5 years after onset corresponds to 3/4 of the disability status after 15 years. The number of relapses diminishes naturally over the course of the disease. Presence and extent of lesions on the initial MRI of the brain in clinically isolated syndromes are valuable predictors of dissemination of the disease process over the following 5-10 years. New therapies (e.g. interferon beta 1b and 1a, copolymer 1) reduce relapse frequency by 1/3 and diminish the extent of pathological lesions in brain MRI, but fail to show (as yet) significant influence on disability.