Sweating impairment in patients with multiple sclerosis.

OBJECTIVES: To measure sweating in patients with multiple sclerosis (MS). MATERIALS AND METHODS: Sweating was measured by an evaporimeter after a heating stimulus in 29 MS patients and in 15 healthy control subjects. RESULTS: The MS patients sweated markedly less than the controls. After 10 min of heating the sweating was significantly lower in the forehead (P = 0.034), feet (right, P = 0.033; left, P = 0.037) and legs (right, P = 0.043; left, P = 0.029) of the MS patients than in those of the controls. After 15 min of heating the difference was statistically significant only in the feet (right, P = 0.043; left, P = 0.029). The Expanded Disability Status Scale score correlated inversely with sweating at 15 min of heating in the left hand (r = 0.42, P < 0.05), and in the left (r = 0.36, P < 0.05) and right foot (r = 0.37, P < 0.05). CONCLUSIONS: MS is associated with an impairment in thermoregulatory sweating which seems to be related to the disease severity.

Sympathetic skin responses in multiple sclerosis.

OBJECTIVES: This study assessed the sympathetic skin responses (SSRs) and their correlation with brain lesion volumes in patients with multiple sclerosis (MS). MATERIALS AND METHODS: The SSRs were measured in 27 patients with MS and 27 healthy controls. The volumes of the proton density-weighted MS lesions in the brain were measured using MRI. RESULTS: The SSRs were abnormal in 52% of the patients with MS, but absent only in clinically severe MS. The total lesion volume in the whole brain correlated significantly with both the severity of MS expressed by the EDSS score (P < 0.001) and the decreased SSR amplitudes in the feet (P < 0.01). Focal lesion volumes in the temporal lobe (P < 0.01), in the pons (P < 0.01) and in the cerebellum (P < 0.01) were also separately associated with abnormal SSR reflexes. CONCLUSIONS: Sudomotor regulation failure in MS is associated with certain focal MS lesions.

A handheld nerve conduction measuring device in carpal tunnel syndrome.

OBJECTIVES: The diagnostic utility and reliability of an easy-to-operate novel handheld nerve conduction tester in carpal tunnel syndrome (CTS) were evaluated. MATERIALS AND METHODS: Using the test device, the sensory nerve conductions (SNC) in the median and ulnar nerves were compared with each other in 194 patients with suspected CTS and 95 healthy controls. The test device results were compared with the results of nerve conduction studies (NCS) with traditional instrumentation. RESULTS: The new device correctly classified 145 of the 149 hands (97.3%) without median nerve lesion and 171 of the 200 hands (85.5%) with median nerve lesions in traditional NCS. The specificity of the new tester compared with traditional instrumentation was 98%. The correlation coefficient for different technicians in different studies was 0.87. CONCLUSIONS: The findings obtained with the new tester in CTS were reliable and reproducible. This tester may increase availability of NCS in CTS.

A 3-year clinical follow-up of adult patients with 3243A>G in mitochondrial DNA.

OBJECTIVE: To follow the clinical course of patients with the mitochondrial DNA mutation 3243A>G for 3 years. METHODS: Thirty-three adult patients with the 3243A>G mutation entered a 3-year follow-up study. They were clinically evaluated annually, audiometry was performed, and samples were drawn for the analysis of blood chemistry and mutation heteroplasmy in leukocytes. Holter recording was performed three times during the follow-up and echocardiography, neuropsychological assessment, and quantitative EEG and brain imaging conducted at entry and after 3 years. RESULTS: The incidence of new neurologic events was low during the 3-year follow-up. Sensorineural hearing impairment (SNHI) progressed, left ventricular wall thickness increased, mean alpha frequency in the occipital and parietal regions decreased, and the severity of disease index (modified Rankin score) progressed significantly. The rate of SNHI progression correlated with mutation heteroplasmy in muscle. The increase in left ventricular wall thickness was seen almost exclusively in diabetic patients. Seven patients died during the follow-up, and they were generally more severely affected than those who survived. CONCLUSIONS: Significant changes in the severity of disease, sensorineural hearing impairment, left ventricular hypertrophy, and quantitative EEG were seen in adult patients with 3243A>G during the 3-year follow-up.

Cardiovascular autonomic dysfunction correlates with brain MRI lesion load in MS.

OBJECTIVE: The aim of the present study was to investigate the cardiovascular autonomic control in clinically definite multiple sclerosis (MS) patients with a standardised battery of cardiovascular tests and to correlate these findings with the brain magnetic resonance imaging (MRI) lesion load. METHODS: Fifty-one patients with MS and 50 healthy controls were studied. Brain MRI was performed in all patients showing typical MS lesions. The cardiovascular tests were carried out using a standardised battery. RESULTS: Heart rate (HR) responses to deep breathing (P < 0.05) and tilt table testing (P < 0.001) were significantly decreased in MS patients when compared to those of the controls. Blood pressure (BP) responses in the tilt table test were also impaired in MS patients (diastolic P < 0.001, systolic P < 0.05). Of the different brain areas investigated the total volume of the midbrain MRI lesions (P < 0.05) was the one most clearly associated with the impaired BP responses. CONCLUSIONS: MS results in both reduced HR variation and decreased BP reactions indicating disturbed cardiovascular regulation. In particular, the midbrain lesions found in MS are associated with cardiovascular dysfunction.

Cardiovascular autonomic reactivity is decreased in adolescents with Type 1 diabetes.

AIMS: To characterize autonomic nervous system function by means of the heart rate and blood pressure responses to various stimuli in relation to pubertal maturation in patients with Type 1 diabetes mellitus (DM). METHODS: One hundred out of 138 eligible patients at the Out-patient Diabetes Clinic and 100 healthy control subjects were examined in terms of cardiovascular parameters at rest, during deep breathing and when standing. Heart rate variability was analysed with time domain,frequency domain and fractal dimension parameters. Tanner pubertal staging was performed before the examinations. RESULTS: The time domain parameters of heart rate variability at rest or during standing did not significantly differ between the patients and controls in total or at pubertal stages. In the spectral analysis of heart rate variability the very low frequency band was decreased in the patients during standing (P = 0.023).The increase in the very low frequency (P = 0.013)and low frequency (P = 0.031) spectral powers upon changing from a supine position to standing was attenuated in the patients in total, while no significant differences were observed within the Tanner pubertal stages between patients and controls. Heart rate variability during deep breathing was decreased in the patients with distal polyneuropathy (P = 0.006). CONCLUSIONS: Although cardiovascular integrity is in the main well preserved in adolescent patients with Type 1 DM, these patients are prone to attenuated autonomic nervous system reactivity.

Ubiquinone and nicotinamide treatment of patients with the 3243A-->G mtDNA mutation.

The efficacy and safety of ubiquinone (Q10) and nicotinamide were evaluated in a 6-month open-label trial in patients with the 3243A-->G mitochondrial DNA mutation. Blood lactate and pyruvate concentrations decreased, but there was little clinical improvement. Q10 and nicotinamide were well tolerated, but two patients died suddenly and unexpectedly during the trial. These deaths may have been unrelated to treatment. The unpredictable course of the disease makes evaluation of the clinical response difficult.

Comparison of heart rate variability analysis methods in patients with Parkinson's disease.

The aim of the present study was to evaluate different analysis methods for revealing heart rate variability (HRV) differences between untreated patients with Parkinson's disease and healthy controls. HRV in standard cardiovascular reflex tests and during a 10 min rest period were measured by time- and frequency-domain and geometrical and non-linear analysis methods. Both frequency- and time-domain measures revealed abnormal HRV in the patients, whereas non-linear and geometrical measures did not. The absolute high-frequency spectral power of HRV was the strongest independent predictor to separate the patients from the controls (p = 0.001), when the main time-domain and absolute frequency-domain measures were compared with each other. When the corresponding normalised spectral units, instead of the absolute units, were used in the comparison, the two best single measures for separating the groups were the 30/15 ratio of the tilting test (p = 0.003) and the max/min ratio during deep breathing (p = 0.024). When the correlations between the different measures were estimated, the time-domain measures, fractal dimension and absolute spectral powers correlated with each other. The frequency- and time-domain analysis techniques of stationary short-term HRV recordings revealed significant differences in cardiovascular regulation between untreated patients with Parkinson's disease and the controls. This confirms cardiovascular regulation failure before treatment in the early stages of Parkinson's disease. The HRV spectral powers, in absolute units, were the most effective single parameters in segregating the two groups, emphasising the role of spectral analysis in the evaluation of HRV in Parkinson's disease.

Parasomnias decline during pregnancy.

OBJECTIVES: A survey of the effects of pregnancy on parasomnias. MATERIAL AND METHODS: In an area of a central hospital and the maternity care units in the nearby rural community, women were interviewed during and after their pregnancy with a series of five questionnaires to assess the frequency of their parasomnias. The first questionnaire covered the 3 months before becoming pregnant, the next three the trimesters of pregnancy and the last one the 3 months after delivery. Altogether 325 mothers filled all the five questionnaires and constitute the study group. RESULTS: The total number of parasomnias declined (P < 0.001) during pregnancy and even more among the primiparas than among the multiparas (difference until third trimester, P=0.02). Among various parasomnias reported, sleep talking and sleepwalking decreased from the prepregnant period to the second trimester (22.8 vs 12.6%, change P=0.003), and the reported sleep starts also diminished from the prepregnant time to the first trimester (78.5 vs 63.1%, P < 0.001), but these phenomena did not change further during the follow-up. Altogether 55.7% of the women reported having nightmares 3 months before the pregnancy, and 47.7, 49.5, 41.2 and 40.3% (change from the prepregnant period, P < 0.001), respectively, at first, second and third trimester and after the delivery. Reported hypnagogic hallucinations decreased from the prepregnant time to the first trimester (9.8 vs 6.5%, P=0.027), but returned thereafter to the previous level. During the prepregnant period, 25.8% of the women reported bruxism and only 19.9% during the first trimester (P=0.009). Though the prevalence of sleep paralysis decreased during the first trimester of pregnancy, it was the only parasomnia that increased during later pregnancy (from 5.7 to 13.3% in the second trimester, P < 0.013). CONCLUSIONS: The reported frequency of most parasomnias decreases during pregnancy and even more in primiparas than multiparas.

Heart rate dynamics in refractory and well controlled temporal lobe epilepsy.

OBJECTIVES: Disorders of cardiovascular and other autonomic nervous system functions are often found in patients with temporal lobe epilepsy (TLE). Cardiovascular dysregulation in TLE has previously been quantified assessing traditional time and frequency domain measures of heart rate (HR) variability from short term ECG recordings. However, new complexity and fractal measures of HR variability based on non-linear dynamics and fractals ("chaos theory") may disclose certain patterns of HR dynamics that cannot be detected using only conventional measures. METHODS: In addition to the traditional spectral and non-spectral components of HR variability, fractal correlation properties, approximate entropy (ApEn) of RR interval dynamics, and the slope of the power law relation were measured from 24 hour ambulatory ECG recordings to evaluate interictal autonomic cardiovascular regulatory function in 19 patients with refractory TLE, 25 patients with well controlled TLE, and in 34 healthy age and sex matched control subjects. RESULTS: The traditional time and frequency domain measures were lower in patients with TLE than in controls (p<0.05). In addition, the power law slope (p<0.005) and ApEn (p<0.05) were also reduced in TLE patients. Furthermore, ApEn was smaller in patients with refractory TLE than in patients with well-controlled TLE ( p<0.01), whereas the long term fractal correlation value alpha2 was lower in patients with well controlled TLE (p<0.05). An altered HR variation was not associated with any particular AED regimen. CONCLUSIONS: In addition to reduced overall HR variability, the long term fractal organisation and complexity of HR dynamics seem to be altered in TLE. These abnormalities in HR behaviour may partly contribute to the occurrence of adverse cardiovascular events, such as life threatening arrhythmias in patients with TLE.

Effects of pregnancy on mothers' sleep.

OBJECTIVES: To survey the effects of pregnancy on mothers' sleep. METHODS: Mothers were interviewed during and after pregnancy with a series of five questionnaires to assess alterations in their sleep. The first questionnaire covered the 3 months before becoming pregnant, the next three the trimesters of pregnancy and the last the 3 months after delivery. The study was carried out in a central hospital and the maternity care units in the nearby rural community. Altogether, 325 pregnant women completed all five questionnaires. RESULTS: The total amounts of reported sleep and of nocturnal sleep increased significantly during the first trimester of pregnancy, began to decrease thereafter and were shortest during the 3 months after pregnancy. During late pregnancy expectant mothers over 30 years of age reported less sleep than those under 30. During the whole pregnancy, but increasingly toward the end of pregnancy, sleep became more restless and fragmentary and its subjective quality worsened, due at least partly to increased restless legs and nightly awakenings increasing with advancing pregnancy. CONCLUSIONS: The subjective quality of sleep is disturbed as early as the first trimester of pregnancy, although total sleeping time increases. The amount of reported sleep begins to decrease in the second trimester. The frequency of reported sleep disturbances, such as restless legs syndrome and nocturnal awakenings, is maximum in the third trimester but is about normal within 3 months after delivery.

Peripheral nerve function is increasingly impaired during puberty in adolescents with type 1 diabetes.

OBJECTIVE: To evaluate the impact of puberty on peripheral nerve function in adolescents with type 1 diabetes. RESEARCH DESIGN AND METHODS: Of 138 eligible patients with type 1 diabetes, 100 patients (age >9 years and diabetes duration >2 years) attending an outpatient diabetes clinic and 100 age- and sex-matched healthy control subjects took part in this cross-sectional study. Peripheral motor and sensory nerve conduction tests, cardiovascular reflex tests on the autonomic nervous system, and measurements of vibration-perception threshold (VPT) were performed. RESULTS: Nerve conduction velocity (NCV) in the distal motor and sensory nerves, the motor nerve distal latency, and the sensory nerve action potential (SNAP) amplitude were impaired in the adolescent patients with type 1 diabetes. The deterioration in motor NCV, H-reflex latency, and SNAP amplitude became more conspicuous in late puberty and postpuberty and was related to poor metabolic control. A total of 10 patients had distal diabetic polyneuropathy (DP) neurophysiologically, and these patients had significantly lower heart-rate variation in the deep breathing test than the other patients. Three of the patients with DP had peripheral neurological signs or symptoms. A slight difference in the VPT between the patients and control subjects was observed after puberty. CONCLUSIONS: Increasing subclinical motor nerve impairment can be detected during late puberty and after puberty, and sensory NCV and SNAP amplitude are reduced in adolescents with type 1 diabetes. Poor metabolic control during puberty appears to induce deteriorating peripheral neural function in young patients with type 1 diabetes.

Motor nervous pathway function is impaired after treatment of childhood acute lymphoblastic leukemia: a study with motor evoked potentials.

BACKGROUND: The objective was to evaluate whether motor nervous pathways are affected when patients are treated for childhood acute lymphoblastic leukemia (ALL). PROCEDURE: Thirty-two children with ALL were studied at the end of treatment by means of motor evoked potentials (MEPs) elicited by magnetic stimulation (MS) transcranially and peripherally and underwent a detailed neurological examination. Thirty-two healthy children matched with them for age, sex, and height served as a control group. RESULTS: The latencies of the MEPs were significantly prolonged along the entire motor nervous pathway in the patients with ALL compared with the healthy controls, indicating demyelination in the thick motor fibres. The MEP amplitudes of the distal extremities elicited by stimulation at the brachial plexus and LV spinal level were significantly lowered in the patients treated for ALL, also indicating anatomical or functional loss of descending motor fibres and/or muscle fibres. The MEP amplitudes elicited by cortical MS showed wider variation and no clear abnormalities were found. Neurological signs and symptoms were common after treatment: 41% of the patients had depressed deep tendon reflexes, 31% had fine motor difficulties and 63% gross motor difficulties, and 34% had dysdiadochokinesia. The conduction delay within the peripheral nerve was related to the post-therapeutic interval after administration of vincristine and the lesions within the CNS to the number of injections of intrathecal methotrexate. CONCLUSIONS: The present results show adverse effects of the ALL treatment on the entire motor nervous pathways. In our experience, the measurement of MEPs by MS provides an objective, painless, and practical tool for assessing the treatment-related neurotoxicity in both the CNS and the peripheral nerves. These disturbances in the motor nervous pathways at the end of treatment raise the question of the long-term effects of ALL treatment on the motor nerve tracts, and have led us to employ MEPs to study these effects in long-term survivors of ALL.

Sequelae of moderate finger frostbite as assessed by subjective sensations, clinical signs, and thermophysiological responses.

The aim of the study was to investigate prevalence and qualities of sequelae following moderate finger frostbite. The study material comprised 30 subjects, who had suffered second-degree frostbite (73% contact frostbite) 4-11 years before this study. In clinical tests 66% of the subjects had an elevated tendency for vasospasm, yet only 20% suffered from white fingers. However, no marked traces of frostbite-related alterations were observed in systemic cardiovascular reflex tests or in X-ray examinations of the frostbite area. Subjective assessments revealed a high prevalence of sequelae (63%), although the primary frostbite was moderate and local. The sequelae in the frostbite area included hypersensitivity to cold (53%), numbness of fingers (40%), and declined sensitivity of touch (33%). Also working ability was lowered due to frostbite sequelae (13%). In cold air provocation tests, the skin temperature of the frostbitten areas decreased more quickly and reached lower values than in healthy control subjects. In conclusion the suffered frostbite was associated with an increased tendency for vasospasm. Subjective sensations of the frostbitten area were associated with thermophysiological changes. The sequelae were reported to worsen in the cold environment thus emphasizing the probable occupational limitations of even moderate cold injury.

Central and peripheral nervous system dysfunction in the clinical variation of Salla disease.

OBJECTIVE: To evaluate the degree of possible peripheral nervous system (PNS) involvement in addition to CNS manifestations in Salla disease, a free sialic acid storage disorder leading to severe mental retardation with a wide clinical variation. BACKGROUND: Salla disease is a lysosomal storage disorder that affects the white matter of the CNS. MRI findings and recent 1H MRS study results provide evidence for delayed central myelination, but there is no previous evidence for PNS involvement in this disease. The gene coding for a presumptive sialic acid transport protein has recently been identified, and the first disease-causing mutations have been characterized. METHODS: Nerve conduction studies; evoked potentials to visual (VEP), brainstem auditory (BAEP), and somatosensory stimuli (SEP); and EEG were carried out on 22 patients (age range 2 months to 57 years) with biochemically and genetically confirmed Salla disease. Brain MRI were available on 14 patients. RESULTS: Nerve conduction studies revealed abnormalities in nearly half of the patients (10/21). The four severely disabled patients and the oldest patient had greatly reduced nerve conduction velocities and prolonged distal latencies compatible with demyelinating polyneuropathy. In addition, SEP was abnormal in the majority of the patients, but VEP and BAEP in only a few cases. PNS involvement was clearly associated with both the phenotypic severity and MRI findings. CONCLUSIONS: The results indicate that dysmyelination in Salla disease occurs not only in the CNS but also in the peripheral nervous system, contributing to the phenotypic variation, which can now be correlated with the molecular basis of the disease.

Snoring and obstructive sleep apnea in children: a 6-month follow-up study.

BACKGROUND: Snoring children may present symptoms suggestive of obstructive sleep apnea syndrome (OSAS). Different and controversial methods to establish the diagnosis and to choose the treatment modalities have been proposed. OBJECTIVES: To study children with symptoms raising the suspicion of OSAS with overnight polysomnography (PSG). To evaluate the efficacy of adenotonsillectomy as treatment of pediatric OSAS and to elucidate the natural history of OSAS and primary snoring. DESIGN: A controlled, prospective, nonrandomized clinical trial. SETTING: Academic medical center. SUBJECTS: Fifty-eight snoring but otherwise healthy children aged 3 to 10 years with symptoms suggestive of OSAS underwent PSG twice, 6 months apart. Thirty healthy children served as controls. RESULTS: Twenty-seven children had OSAS with an obstructive apnea/hypopnea index greater than 1, while 31 had primary snoring. There were statistical differences in the symptoms and signs among the 3 study groups. Adenotonsillectomy was curative in the 21 children with OSAS who were operated on. Obstructive apneas and hypopneas in the healthy, nonsnoring children were almost nonexistent in this study. CONCLUSIONS: Half of the children or fewer with symptoms suggestive of OSAS actually had the condition. Clinical symptoms may raise the suspicion, but it is not possible to establish the diagnosis without PSG. Because snoring and obstructive symptoms may resolve over time, a normal PSG finding may help the clinician decide on an observation period. Adenotonsillectomy is curative in most cases of pediatric OSAS. Obstructive symptoms may continue after adenoidectomy alone.

Nasalance scores in snoring children with obstructive symptoms.

OBJECTIVE: Snoring and the sleep apnea syndrome (OSAS) in children are usually caused by adenotonsillar hypertrophy, which may affect air escape into the nose and nasal resonance. A microcomputer-based system makes it possible to objectively determine whether the oral passage is adequately separated from the nasal passage during phonation. The score thus obtained is called nasalance. This study was conducted to verify whether there exists differences in nasalance between primary snorers and OSAS-children. DESIGN: Fifty-three habitually snoring children (31 boys), mean age 6.1 years (range 3.2-10.5 years), were subjected to overnight sleep polygraphy (PG) and nasalance measurements with the Nasometer 6200. The study was successfully repeated 6 months later on 36 children. RESULTS: Nineteen children had obstructive apnea-h ypopneaindex (OAHI)> 1 on overnight polygraphy (OSAS-children), while 32 were considered primary snorers (PS), (OAHI<1). No statistically significant difference in nasalance scores was found between the OSAS- and PS children. Both groups of children had somewhat higher mean nasalance values both for oral and nasal passage sentences than the normative values for Finnish speech. In general, the most habitual snorers had lower nasalance scores than the less frequently snoring children (P=0.05). Earlier adenoidectomy or palatine tonsillar size did not have a significant influence on the nasalance. Adenotonsillectomy did not affect the nasalance scores of the nine children operated on during the follow-up period. CONCLUSIONS: According to the present study, nasalance measurements cannot be used to predict the incidence of OSAS among snoring children.

Motor evoked potentials of subjects over 70 years of age with and without recurrent falls.

Motor evoked potentials (MEPs) of 83 elderly (79+/-4 years) subjects, 43 with recurrent falls and 40 without, and of 31 healthy young (42+/-9 years) subjects were measured from thenar (and hypothenar) and tibialis anterior muscles. Forty-four of the aged subjects without overt neurological diseases were used as controls. Absolute latencies from the cortex to the target muscles as well as the latency differences from the cortex to the level of the fifth lumbar vertebra (LV) were longer in the aged than in the young, but the latency difference from the cortex to the brachial plexus was shorter. The cortical, brachial plexus and lumbar (LV) latencies were all dependent on height as well as age. The latency differences from the cortex to the plexus or LV were not height-dependent but were age-dependent. The thenar MAXMEP/CMAP ratio was significantly higher in hands with thenar atrophy (in 30% of the aged subjects) than without; thenar atrophy thus excludes the use of this parameter in about one-third of the aged subjects. There were no significant differences in the MEP latencies or amplitudes of the recurrent fallers and the non-fallers. Subjects having more frequent falls, however, tended to have lower amplitudes of MEPs in the lower extremities.

Auditory P300 event related potential in minor ischemic stroke.

OBJECTIVE: Various degenerative cerebral diseases and even depression may cause abnormalities of the cognitive event related potentials (ERPs). We conducted the present study to elucidate the effects of ischemic stroke on the P300 ERP component. MATERIAL AND METHODS: We recorded the P300 wave using an auditory oddball paradigm in 38 consecutive brain infarct patients with mild neurological deficits at 3 and 12 months post-stroke, and in 29 healthy control subjects. RESULTS: Brain infarction slightly prolonged the P300 latency, and the observed delay was related to the presence and degree of post-stroke depression evaluated with the Zung Depression Scale and the DSM-III criteria. Infarction did not affect the P300 amplitude or its distribution on the scalp. The results of the patients with hemispheric brain infarction and those of the patients with brainstem infarction were similar, and also the values of the patients with the left- and right-sided lesions. The normal physiological correlation between subject age and the P300 latency was absent at 3 months post-stroke, but was present at 12 months post-stroke. CONCLUSION: Brain infarction delays the P300 ERP and temporarily distorts its age-related physiology. The increase of the P300 latency seems to be associated with the post-stroke depression.

Stretch- and H-reflexes of the lower leg during whole body cooling and local warming.

BACKGROUND: This study was undertaken to evaluate if possible changes in stretch- and H-reflexes could be related to the changes in the EMG activity of the cooled lower leg muscles observed during a stretch-shortening cycle exercise. METHODS: Eight subjects wearing shorts and jogging shoes were exposed once to 27 degrees C and twice to 10 degrees C for 60 min each. During the second exposure to 10 degrees C, the subject's lower legs were kept warm (10 degrees Clw) with electrical pillows. After the exposures Achilles tendon reflex (stretch reflex) was induced and the EMG activity of the triceps surae was measured. Immediately after reflex measurements the EMG activity of the triceps surae and tibialis anterior during a drop-jump (stretch-shortening cycle) was measured. After similar thermal exposures electrically induced H-reflex from the calf was measured. RESULTS: During the preactivity and stretch phases the EMG activity of the triceps surae increased after the exposure to 10 degrees C, whereas during the shortening phase it decreased. During the shortening phase cooling, on the contrary, increased the activity of tibialis surae anterior. These changes disappeared at 10 degrees Clw. At 10 degrees C the maximum EMG-amplitude of triceps surae during stretch reflex decreased (p<0.05), reflecting suppressed muscle spindle activity. Suppressed spindle activity causes the agonist to be unfacilitated and the antagonist muscle contraction to be uninhibited, which was seen in the present study as decreased agonist and increased antagonist EMG activity during the shortening phase at 10 degrees C. The Hmax/Mmax-ratio, H-reflex latency and amplitude increased at 10 degrees C (p<0.05), reflecting increased motoneuron pool excitability. This in part may explain the increased EMG activity during the preactivity and stretch phases. CONCLUSION: Cooling-induced increase in the excitability of the motoneuron pool and suppression of muscle spindle activity seem to be responsible of the EMG activity changes during the stretch-shortening cycle, consequently decreasing muscular performance.