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Biomedical subjects

U Tolonen

Publications and source records attributed to U Tolonen.

At least 37 records · Page 2Linked to original sources
PubMed2000

Interictal cardiovascular autonomic responses in patients with temporal lobe epilepsy.

PURPOSE: To measure interictal cardiovascular autonomic functions in patients with either refractory or well-controlled temporal lobe epilepsy (TLE). METHODS: For autonomic assessment, heart rate variation during normal and deep breathing, Valsalva maneuver, and tilting were measured in 19 patients with chronic refractory TLE, 19 patients with well-controlled TLE, and 38 age- and sex-matched healthy control subjects. Blood pressure responses to tilting and isometric work also were evaluated. RESULTS: Heart-rate (HR) variation during normal breathing (p = 0.006) and tilting (p = 0.043) was lower in patients with refractory TLE than in control subjects. Heart-rate response to tilting (p = 0.036) was also lower in patients with well-controlled TLE than in control subjects. Blood-pressure responses showed no differences between the patients and the control subjects. Patients taking carbamazepine (CBZ) medication had decreased HR responses to deep breathing (p = 0.046) and to tilting (p = 0.014) compared with the control subjects. CONCLUSIONS: Refractory TLE seems to be associated with dysfunction of the cardiovascular autonomic regulation, manifesting as impaired HR responses to certain stimuli. Interictal autonomic dysfunction is seen in patients with well-controlled TLE as well, but it may be more evident in patients with refractory epilepsy. CBZ medication may also be associated with altered autonomic cardiac control.

Adult↗
PubMed2000

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.

Adult↗
PubMed2000

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.

Adult↗
PubMed1998

Interictal cardiovascular autonomic responses in patients with epilepsy.

PURPOSE: To evaluate the interictal autonomic nervous system function in 84 patients with epilepsy: 37 with newly diagnosed, previously untreated epilepsy, and 47 patients receiving long-term carbamazepine (CBZ), phenytoin (PHT), or valproate (VPA) monotherapy, or CBZ plus PHT, or CBZ plus VPA for their seizure disorder. METHODS: We assessed autonomic control of the cardiovascular regulatory system by standardized cardiovascular reflex tests measuring changes in heart rate (HR) and blood pressure (BP) at rest and after certain stimuli. RESULTS: The HR and BP responses were similar to those of control subjects in patients with newly diagnosed epilepsy. However, HR variation during normal breathing and maximum systolic BP increase in isometric work were diminished in patients, who had been treated with antiepileptic drugs (AEDs) for epilepsy for a long time. Diminished HR responses to the Valsalva maneuver were noted in patients receiving CBZ as monotherapy and during deep breathing in patients receiving CBZ combined with PHT or VPA. Furthermore, patients receiving CBZ had diminished BP responses in isometric work. When analyzed in relation to epilepsy type, suppressed HR responses in normal breathing were associated with primary generalized epilepsy (PGE), whereas diminished BP responses in isometric work were associated with partial epilepsy. Two patients with recently diagnosed partial epilepsy and 1 patient receiving long-term CBZ monotherapy for partial epilepsy had two abnormal cardiovascular response test results. CONCLUSIONS: Our results show that cardiovascular responses mediated by both the parasympathetic and sympathetic nervous system are diminished in patients with epilepsy. However, the changes appear to be clinically significant in only a few of them and appear to be associated with CBZ medication. Further studies are needed to detect the underlying complex interactions and clinical significance of autonomic nervous system dysfunction in patients with epilepsy.

Adolescent↗
PubMed1997

Chemotherapy for acute lymphoblastic leukemia may cause subtle changes of the spinal cord detectable by somatosensory evoked potentials.

Intrathecal chemotherapy has been determined to cause transient or permanent paraparesis due to myelopathy in patients with leukemia or other malignancies. To systematically evaluate the effect of methotrexate on spinal cord function, somatosensory evoked potentials (SEP) were measured in children with acute lymphoblastic leukemia (ALL). A prospective evaluation was performed in 38 consecutive children aged 1.4-15.3 years with newly diagnosed ALL during treatment. Intrathecal methotrexate therapy was included in the therapy schedule of all patients as central nervous system (CNS) therapy in addition to intravenous chemotherapy in 19 standard risk patients and intravenous chemotherapy with cranial irradiation in 19 intermediate or high-risk patients. The measured conduction times were compared with those of 38 control children matched for age, height, and sex. A significant increase in the conduction time of the tibial nerve SEP was found between the Th12 level and the cortex in children with ALL after receiving intrathecal methotrexate therapy during the induction and CNS therapy phases when compared with their controls. The difference of the mean latencies was 1.45 ms (95% CI 0.39-2.51; P < 0.01). There was no significant delay in the median nerve SEP from the brain stem to the cortex, indicating that the conduction delay was in the area of the spinal cord exposed to intrathecal methotrexate. Moreover, the cortical amplitudes of the median nerve SEPs were significantly reduced when measured immediately after intravenous and intrathecal methotrexate and compared to the amplitudes measured after induction therapy in standard risk patients (P = 0.001). Intrathecal methotrexate with systemic chemotherapy causes a deterioration in the somatosensory pathways within the CNS, suggesting also spinal cord dysfunction in children with ALL in addition to the cerebral dysfunction described earlier.

Adolescent↗
PubMed1997

Selegiline diminishes cardiovascular autonomic responses in Parkinson's disease.

Selegiline (L-deprenyl), a selective inhibitor of monoamine oxidase type B, is an established adjuvant to levodopa therapy in Parkinson's disease (PD). To evaluate whether selegiline also effects the severity and progression of autonomic nervous system dysfunction in PD, we studied autonomic functions by measuring cardiovascular responses to normal breathing, deep breathing, the Valsalva maneuver, the tilting test, and the isometric contraction test prospectively in 52 PD patients receiving either selegiline (n = 27) or placebo (n = 25) in randomized order in a double-blind parallel trial. The study also continued double-blind after the introduction of levodopa. Recordings of cardiovascular responses were carried out annually, with the median follow-up period being 6 years. Cardiovascular autonomic reflexes were diminished in the patient groups compared with those of healthy control subjects (n = 45). There was no progression (except age-related) in dysautonomia in patients on placebo, but there was a decrease in cardiovascular responses in the selegiline group. The heart rate variability in normal breathing, in the Valsalva maneuver, and in the tilting test was clearly diminished during the selegiline treatment. In addition, in the tilting test, the fall in diastolic blood pressure immediately after tilting and in systolic blood pressure 2 minutes after standing up was more pronounced in the selegiline group than in the placebo group. Levodopa treatment had no effect on the measured autonomic responses. In the isometric contraction test, the two treatment groups showed no difference. We conclude that selegiline treatment diminishes autonomic responses, especially those of the sympathetic division. This sympatholytic effect may signal an increased risk of orthostatic hypotension.

Analysis of Variance↗
PubMed1997

Snoring children: factors predicting sleep apnea.

Many snoring children present obstructive symptoms according to their parents. The seriousness of the symptoms and the possibility of the obstructive sleep apnea syndrome (OSAS) in these children may be difficult to judge on the basis of the clinical findings and the patient's history only. In order to evaluate snoring children's relative risk (RR) to have OSAS, their symptoms and signs, as reported by the parents, and clinical findings were compared with the results of overnight polysomnography (PSG). An obstructive apnea index (AI) > or = 1 in PSG was regarded as the criterion for OSAS. The mean AI was 1.55 (range 0-15), and 29 children had a pathological AI, while 49 had a normal PSG recording. Apneic episodes every night detected by the parents was the most important single risk factor for OSAS (RR 3.6, 95% confidence interval (CI) 1.7-7.7). The RR ratio decreased when apneas appeared less frequently, but any detected apnea was still a single risk factor (RR 1.4, CI 1.2-1.8). The other risk factors of night-time symptoms were constant snoring (RR 1.5, CI 1.0-2.1) and restless sleep (RR 2.1, CI 1.1-4.0). Of the daytime symptoms, absence of excessive sleepiness was a protective factor against OSAS (RR 0.3, CI 0.1-1.0). Previous adenoidectomy was found to be a risk factor (RR 1.7, CI 1.1-2.7), as was tonsillar enlargement (RR 1.4, CI 1.1-1.8). These two findings suggest that the epipharyngeal space does not play a central role in the development of OSAS in children. OSAS cannot be reliably diagnosed without PSG, which is the most important examination for snoring children with obstructive symptoms. For clinical decisions, the consideration of risk factors is essential.

Adenoidectomy↗
PubMed1995

Responses of workers exposed to vibration in autonomic nervous function tests.

Heart rate variation in quiet breathing and deep breathing tests and the response of blood pressure in a cold pressor test were measured in 34 railway workers and 13 lumberjacks. The age-adjusted results showed a significant relationship between exposure to hand-arm vibration and the coefficient of beat-to-beat variation in the quiet breathing test (CVS) in the railway workers. The vibration-induced white finger (VWF) and non-VWF subjects showed non-significant differences in respect of all the indices used. This investigation, in common with previous results, suggests that vibration might cause changes in cardiovascular reflexes, but the indices used here seem to be of low sensitivity, at least partially due to wide physiological variation; other more suitable indicators and studies of the pathophysiological background of the suspected effect are needed to confirm the results.

Adult↗
PubMed1995

Vincristine therapy for children with acute lymphoblastic leukemia impairs conduction in the entire peripheral nerve.

Somatosensory evoked potentials were measured prospectively in 38 children with acute lymphoblastic leukemia to evaluate the side effects of vincristine therapy on conduction of the peripheral nerves. Nineteen patients at standard risk received vincristine 12 mg/m2 during induction therapy and 19 patients at intermediate or high risk received 6 mg/m2 during induction therapy and an additional 6 mg/m2 during delayed intensification therapy. These latencies were compared with those of 38 age-, height-, and sex-matched controls. A prolongation in the peripheral conduction time of the posterior tibial nerve was found in the standard risk patients after induction compared with that of the controls, and a delay was found not only from the ankle to the popliteal fossa, but also from the popliteal fossa to the spinal cord (P < .01). The conduction times of the median nerve from the wrist to the plexus (P < .01) and from the wrist to the spinal cord (P < .01) were prolonged after delayed intensification therapy. There was a significant delay in the median and tibial nerve conduction between the intermediate and high risk patients and their controls after a total vincristine dose of 12 mg/m2. These delays were found along the entire length of the nerves, especially in the proximal part of the tibial nerve (P < .001).

Adolescent↗
PubMed1995

Demyelinating polyneuropathy in a patient with the tRNA(Leu)(UUR) mutation at base pair 3243 of the mitochondrial DNA.

A novel feature of demyelinating polyneuropathy was observed in a patient with the tRNA(Leu(UUR)) mutation at base pair 3243 of the mitochondrial DNA. Based on electrodiagnostic examination, the polyneuropathy was defined as being of the demyelinating, mixed (motor more than sensory) type. In a 1-year follow-up we observed approximately 7% reduction in both the motor and sensory conduction velocities. The other clinical features of the proband included a mild to moderate cognitive impairment and a combined hearing loss with a moderate sensorineural component. The proportion of the mutant genome found in the muscle of the proband was 29%, but the mutation was not found in his blood. A wide variability of the clinical phenotype was observed in the family of the proband. Heteroplasmic mutation was detected in the blood of most family members. The proportion of abnormal mitochondrial DNA was highest in the proband's brother, who had clinically definite mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome, while the mutant genome was less frequent or absent in the subjects with less severe phenotypes and in healthy individuals. The findings on this pedigree emphasize the need for studies of complete families in the search for new clinical phenotypes of mutations in mitochondrial DNA.

Adult↗
PubMed1994

Cardiovascular autonomic reflexes in brain infarction.

BACKGROUND AND PURPOSE: Increased sympathetic activity is associated with cardiovascular complications in stroke, but the role of the parasympathetic nervous system has not been carefully outlined. In the present study our purpose was to assess quantitatively autonomic cardiovascular disturbances in brain infarction by measuring cardiovascular autonomic reflexes. METHODS: We studied the autonomic regulation of cardiovascular functions prospectively in 40 patients with brain infarction (acute phase, 1 month, and 6 months) and in 55 healthy control subjects by recording heart rate and blood pressure responses to normal and deep breathing, the Valsalva maneuver, tilting, and isometric work. RESULTS: In the acute phase, heart rate responses to normal breathing, deep breathing, the Valsalva maneuver, and tilting were significantly (P < .05) impaired in both hemispheric and brain stem infarctions, thus indicating hypofunction of the parasympathetic nervous system. At 1 month heart rate responses to normal breathing (brain stem, P < .05), the Valsalva maneuver (brain stem, P < .01), and tilting (hemispheric, P < .05) were still significantly lower than those of the control subjects, but at 6 months significant suppression of the response was found only in tilting (hemispheric, P < .05). CONCLUSIONS: These findings suggest that in addition to the previously well-established sympathetic hyperfunction, brain infarction also seems to cause parasympathetic hypofunction, brain which may be involved in cardiovascular and other known manifestations of autonomic failure associated with stroke.

Adult↗
PubMed1993

Cerebral trauma and alcohol abuse.

We report results of clinical examinations, computed tomography, quantitative electroencephalography (QEEG), and cerebral blood flow measurements performed on a series of 56 consecutive brain injury patients including 15 alcohol abusers and 41 non-alcoholic subjects. Greater volumes of intracranial haemorrhage were noted in the alcoholics for a similar severity of injury and local brain atrophy became more pronounced in them during a follow-up of 1 year. After this time, the third ventricle width, distance between frontal horns, the sum of lateral ventricle dimensions and cortical sulci were all markedly larger in the alcoholics. The QEEG results also indicated a weaker improvement in the alcoholics. The cerebral blood flow at the site of the injury was initially slow in the alcoholics when compared to the contralateral region of the other hemisphere, although these differences disappeared during the follow-up. Permanent occupational disability was also found to be associated with pretraumatic alcohol abuse. The findings indicate that ethanol abuse is not only commonly associated with cerebral trauma but is also a risk factor for a more severe brain damage following the injury.

Adult↗
PubMed1993

Suppressed sympathetic skin response in brain infarction.

BACKGROUND AND PURPOSE: Autonomic failure is known to manifest commonly in stroke, but very little attention has been given to various features of sympathetic dysfunction such as sudomotor dysregulation in cerebrovascular diseases. In the present study, our purpose was to assess quantitatively sympathetic reflex activity in brain infarction by measuring the sympathetic skin response. METHODS: We recorded the sympathetic skin response to electric and auditory stimulations simultaneously on both hands in 58 patients with brain infarction and in 36 healthy control subjects. RESULTS: The response amplitudes were significantly decreased and the latencies prolonged in both hemispheral (n = 49) and brain stem (n = 9) infarctions compared with the control subjects. The amplitudes were diminished in both the acute and late phases of infarction, but the latencies were prolonged only in the acute phase. CONCLUSIONS: Sympathetic dysfunction in brain infarction seems to be much more extensive than has previously been thought. In the present study, we have demonstrated impaired sympathetic skin responses, reflecting definite suppression of the reflex activity of the sympathetic nervous system.

Acoustic Stimulation↗
PubMed1993

A prospective one-year follow-up study with somatosensory potentials evoked by stimulation of the median nerve in patients with cerebral infarct.

Somatosensory potentials evoked by stimulation of the median nerve (median nerve SEPs) were studied in a prospective and sequential series of 40 patients with first supratentorial and nonhaemorrhagic cerebral infarct. In 35 patients the SEPs were recorded three times during the first year after the stroke. The location of the infarcted zone was reflected in the number of detected abnormalities: most patients with infarct changes extending to the gray matter of the Rolandic cortex showed abnormalities in the median nerve SEPs, and all patients with involvement of both precentral and postcentral cortical gray matter had abnormal median nerve SEPs. In the entire patient group when both latency and amplitude abnormalities were included about half (48%) of the patients had abnormal median nerve SEPs a week after the stroke, 39% 2-3 months after the stroke and 29% about one year after the stroke. These changes were not significant. When separately surveying the changes in the numbers of latency and amplitude abnormalities the difference between the first and the third examinations was nearly significant only in the number of latency abnormalities. Furthermore, in the absolute latency and amplitude values, no significant changes could be seen within the first two-three months after the infarct; within the whole one-year follow-up period a nearly significant change was noted between the second and the third examination in only one parameter (P22 peak latency). Thus, the abnormalities in the median nerve SEPs, especially the amplitude abnormalities, were relatively permanent during the one-year period after cerebral infarct.

Adult↗
PubMed1992

Effect of reinnervation on collagen synthesis in rat skeletal muscle.

The effect of reinnervation on the activities of prolyl 4-hydroxylase (PH) and galactosylhydroxylysyl glucosyltransferase (GGT), both enzymes of collagen biosynthesis, and on the concentration of hydroxyproline (Hyp) was studied in gastrocnemius, soleus, and tibialis anterior muscles of rat 19, 26, 40, and 61 days after crush denervation of the sciatic nerve. The GGT activity was elevated in denervated gastrocnemius and soleus muscles and the PH activity in gastrocnemius. Muscular Hyp concentration was increased in denervated tibialis anterior muscle. Both the PH and GGT activities and the Hyp concentration returned to the control level during the reinnervation period (19-61 days from the start of denervation). It seems that denervation atrophy of skeletal muscle is associated with an increased rate of muscular collagen biosynthesis and that during reinnervation collagen synthesis rate decreases despite accelerated muscular growth. The results thus suggest that innervation is a powerful suppressive regulator of muscular collagen biosynthesis.

Animals↗
PubMed1991

Median nerve and posterior tibial nerve somatosensory evoked potentials in the non-affected hemisphere: a prospective one-year follow-up study in patients with supratentorial cerebral infarction.

Somatosensory potentials in the non-affected hemisphere evoked by simulation of both the median nerve (median nerve SEPs) and the posterior tibial nerve (tibial nerve SEPs) were studied in 40 patients with supratentorial nonhaemorrhagic cerebral infarction three times during a one-year follow-up period. The EP-N20 interpeak latencies (IPLs) of the median nerve SEPs were on average longer in the patient group than in the control group (especially in patients with evidence of mass displacements in the cerebral computed tomography), whereas no significant differences were observed in the amplitudes of the median nerve SEPs. The P57-N75 amplitudes of the tibial nerve SEPs were on average lower in the patient group than in the control group. During the follow-up period the peak latencies and the P40-N75 IPLs of the tibial nerve SEPs increased and the amplitudes of the tibial nerve SEPs diminished.

Cerebral Infarction↗
PubMed1990

Does ephedrine influence newborn neurobehavioural responses and spectral EEG when used to prevent maternal hypotension during caesarean section?

The recovery of 16 infants born by elective caesarean section with spinal anaesthesia, in which either ephedrine or fluid load was used to prevent maternal hypotension, were studied using Scanlon's neurobehavioural tests and a computerized EEG. Neurobehavioural testing showed no differences between the ephedrine and the non-ephedrine groups of infants at ages of 3 h, 1 day, 2 days and 4-5 days, whereas the spectral EEG showed significant differences between the two groups during the first 2 h after delivery, which had disappeared 24 h later. It is suggested that small doses of ephedrine given to the mother i.v. to prevent hypotension during spinal anaesthesia have short-lived effects on the neonate's central nervous system, which will be detected in the spectral EEG, but not in neurobehavioural tests.

Adult↗