Biomedical subjects

S Avikainen

Publications and source records attributed to S Avikainen.

7 recordsLinked to original sources

PubMed2005

Admission blood glucose and short term survival in primary intracerebral haemorrhage: a population based study.

BACKGROUND: The role of admission blood glucose level on the prognosis of patients with intracerebral haemorrhage has not been elucidated. OBJECTIVE: To examine this association on the basis of an epidemiologically representative patient material. METHODS: 249 500 people living in the catchment area of the Central Hospital of Central Finland. The diagnosis of ICH was established if verified by cranial computed tomography (CT) or autopsy. RESULTS: Of the 416 patients who fulfilled the diagnostic criteria, 30 died before admission and 386 were admitted to the Central Hospital. All 329 patients (290 nondiabetics and 39 diabetics) with both admission blood glucose and cranial CT data were included in the study. The mean blood glucose level was 10.6 mmol/l for nondiabetics who died on the day of onset, 8.6 mmol/l for those dying during days 1 to 28, and 6.8 mmol/l for the 28 day survivors. The corresponding figures for diabetics were 13.9 mmol/l, 12.5 mmol/l, and 9.3 mmol/l. In both nondiabetics and diabetics, patients who died had significantly higher mean glucose than the 28 day survivors (p<0.0001 versus p = 0.029). However, blood glucose of the surviving diabetics was as high as that of the deceased nondiabetics (9.3 mmol/l versus 9.1 mmol/l). In nondiabetics, admission blood glucose was associated with parameters signifying severe stroke; disturbed consciousness, large haematoma volume and shift of cerebral midline structures, and high admission mean arterial pressure. In logistic regression analysis, high admission blood glucose in nondiabetics was a significant predictor of death during the first 28 days of onset (odds ratio 1.22, 95% CI 1.07 to 1.40). CONCLUSIONS: High admission blood glucose predicts increased 28 day case fatality rate in both nondiabetic and diabetic patients with ICH. Because high admission blood glucose was associated with markers of severe stroke, we are inclined to support the stress theory; high admission blood glucose is the result of a serious ICH.

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PubMed2005

Long term survival after primary intracerebral haemorrhage: a retrospective population based study.

OBJECTIVES: To determine the long term survival and predictors of death in patients with primary intracerebral haemorrhage (ICH) in Central Finland. METHODS: Data were collected retrospectively on all adult patients with first ever ICH in Central Finland county between September 1985 and December 1991. The survival of all patients at the end of December 2002 was investigated. Kaplan-Meier survival curves were constructed and factors associated with both early (< or =28 days) and late deaths determined. Long term survival was compared with the general Finnish population of the same age and sex distribution. The causes of death were compared with those of the population of Central Finland. RESULTS: 411 patients with first ever ICH were identified, 199 men (mean age 64.9 years) and 212 women (mean age 69.5); 30 died before hospital admission, and 208 (50.6%) within the first 28 days. In Kaplan-Meier analysis, at 16 years the cumulative survival was 3.2% for men and 9.8% for women. The 28 day survivors had a 4.5-fold increased annual risk of dying during the first year after ICH, and 2.2-fold during years 2 to 6. On admission, significant independent predictors of death within the first four weeks were unconsciousness, lateral shift of cerebral midline structures, mean arterial pressure > or =134 mm Hg, hyperglycaemia, anticoagulant treatment, and ventricular extrasystoles. Predictors of late death for the 28 day survivors were old age, male sex, and heart failure. CONCLUSIONS: Primary intracerebral haemorrhage has a poor short and long term outcome. The results emphasise the importance of primary and secondary prevention for ICH.

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PubMed2001

Stronger reactivity of the human primary motor cortex during observation of live rather than video motor acts.

The monkey premotor cortex contains neurons that are activated both when the monkey performs motor acts and when he observes actions made by others. A similar mirror neuron system, involving several brain areas, has been found in humans. We recorded neuromagnetic oscillatory activity from the primary motor cortex of 10 healthy subjects when they observed live and videotaped finger movements. The left and right median nerves were stimulated alternatingly and the poststimulus level of the approximately 20 Hz rhythm was quantified. Compared with the rest condition, the approximately 20 Hz rhythm was dampened 15-19% more when the subjects observed live rather than videotaped hand movements, indicating stronger activation of the primary motor cortex. These results suggest that the human mirror neuron system differentiates natural and artificially presented movements.

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PubMed2001

Three-dimensional integration of brain anatomy and function to facilitate intraoperative navigation around the sensorimotor strip.

We studied 12 patients with brain tumors in the vicinity of the sensorimotor region to provide a preoperative three-dimensional visualization of the functional anatomy of the rolandic cortex. We also evaluated the role of cortex-muscle coherence analysis and anatomical landmarks in identifying the sensorimotor cortex. The functional landmarks were based on neuromagnetic recordings with a whole-scalp magnetometer, coregistred with magnetic resonance images. Evoked fields to median and tibial nerve and lip stimuli were recorded to identify hand, foot and face representations in the somatosensory cortex. Oscillatory cortical activity, coherent with surface electromyogram during isometric muscle contraction, was analyzed to reveal the hand and foot representations in the precentral motor cortex. The central sulcus was identified also by available anatomical landmarks. The source locations, calculated from the neuromagnetic data, were displayed on 3-D surface reconstructions of the individual brains, including the veins. The preoperative data were verified during awake craniotomy by cortical stimulation in 7 patients and by cortical somatosensory evoked potentials in 5 patients. Sources of somatosensory evoked fields identified correctly the postcentral gyrus in all patients. Useful corroborative information was obtained from anatomical landmarks in 11 patients and from cortex-muscle correlograms in 8 patients. The preoperative visualization of the functional anatomy of the sensorimotor strip assisted in designing the operational strategy, facilitated orientation of the neurosurgeon during the operation, and speeded up the selection of sites for intraoperative stimulation or mapping, thereby helping to prevent damage of eloquent brain areas during surgery.

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PubMed1999

Normal movement reading in Asperger subjects.

Patients with autism and Asperger syndrome (AS) are impaired in mindreading and imitation skills. One possibility would be that their 'mirror neuron' system, which matches action execution and observation, does not function properly. To test this hypothesis we compared action-viewing related motor cortex functions in an AS group (one autistic and four AS subjects) and eight control subjects. In both groups viewing hand actions modified the neuromagnetic approximately 20 Hz oscillatory activity in the primary motor cortex to the same extent. Thus impaired mindreading and imitation skills found in AS and autism do not seem to result from dysfunction of the motor cortex part of the action execution/observation system.

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PubMed1998

Activation of human primary motor cortex during action observation: a neuromagnetic study.

The monkey premotor cortex contains neurons that discharge during action execution and during observation of actions made by others. Transcranial magnetic stimulation experiments suggest that a similar observation/execution matching system also is present in humans. We recorded neuromagnetic oscillatory activity of the human precentral cortex from 10 healthy volunteers while (i) they had no task to perform, (ii) they were manipulating a small object, and (iii) they were observing another individual performing the same task. The left and right median nerves were stimulated alternately (interstimulus interval, 1.5 s) at intensities exceeding motor threshold, and the poststimulus rebound of the rolandic 15- to 25-Hz activity was quantified. In agreement with previous studies, the rebound was strongly suppressed bilaterally during object manipulation. Most interestingly, the rebound also was significantly diminished during action observation (31-46% of the suppression during object manipulation). Control experiments, in which subjects were instructed to observe stationary or moving stimuli, confirmed the specificity of the suppression effect. Because the recorded 15- to 25-Hz activity is known to originate mainly in the precentral motor cortex, we concluded that the human primary motor cortex is activated during observation as well as execution of motor tasks. These findings have implications for a better understanding of the machinery underlying action recognition in humans.

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PubMed1997

Prognostic value and determinants of first-day mean arterial pressure in spontaneous supratentorial intracerebral hemorrhage.

BACKGROUND AND PURPOSE: The onset of spontaneous intracerebral hemorrhage (ICH) is often accompanied by transient blood pressure (BP) elevation. The prognostic value and the determinants of this BP reaction have not entirely been solved, and the present study was focused on these questions. METHODS: From 1985 to 1991 in Central Finland (population, 246,000), a total of 425 patients had first-ever ICH verified by CT or necropsy. The hematoma was supratentorial in 337 patients. Of the 306 patients with supratentorial ICH who had CT, 282 had the BP measured at least once within 24 hours of onset, and they formed the study population. The case notes and CT films were reviewed, and mean arterial pressure (MAP) was calculated from the highest BP reading. RESULTS: The fatality rate was high; 43% of the patients were dead within 28 days of onset. Six independent predictors of the 28-day survival were identified by multiple logistic regression; these predictors were consciousness on admission, first-day MAP, subarachnoid spread of the bleed, lateral shift of hemispheral midline structures, admission blood glucose, and vomiting. The MAPs varied between 66.7 and 203.3 mm Hg, and the cutoff points of the MAP quartiles were 118, 132, and 145 mm Hg. Patients in the first three MAP quartiles had relatively fair outcome, with 71%, 65%, and 60%, respectively, alive 28 days after onset. This was in sharp contrast to the fourth quartile, with only 33% surviving the first 28 days (log-rank, P < .0001 to P = .0010). Patients unconscious/ comatose on admission had significantly higher MAPs than did those who were alert or somnolent/disoriented (ANOVA, P = .0079). However, at all levels of consciousness, the 28-day fatality rate increased from the first to the fourth MAP quartile: 69% in the alert, 186% in the somnolent/disoriented, and 45% in the unconscious/comatose patients. Stepwise multiple regression analysis gave four independent predictors of the first-day MAP: hypertension, age (in an inverse fashion), admission blood glucose, and hematoma volume. CONCLUSIONS: The most important predictor of the 28-day survival was the level of consciousness on admission, followed by first-day MAP. Hypertension was the most important predictor of the first-day MAP, followed by age, which had an inverse effect on the MAP level. At all levels of consciousness, high first-day MAP (especially if > 145 mm Hg) worsened the 28-day survival rate.

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