A Servo

Helsinki University Central Hospital, Helsinki, Province of Southern Finland, Finland

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Publications (46)104.75 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: According to earlier findings, letter fluency, repetitive pattern drawing and figural fluency are more sensitive to anterior than to posterior brain lesions. The aim of this study was to demonstrate that the percentage impairments from the single-task results are more pronounced after anterior than after posterior lesions when letter fluency is performed simultaneously with pattern drawing or figural fluency. The single-task results showed no significant differences between the patients with anterior and posterior lesions. The patients with anterior lesions, especially those with left-anterior lesions, had more pronounced percentage dual-task impairment than the other patients in letter fluency but not in pattern drawing or figural fluency. The results did not confirm the prediction that the average of the percentage decrements of the concurrent performances (the combined dual-task cost) or the larger of the two decrements would be more pronounced after anterior than posterior lesions. However, the patients with left-hemisphere lesions were inferior to those with right-hemisphere lesions in the single letter-fluency task, and the combined dual-task cost was more pronounced after left-hemisphere lesions.
    Neuropsychologia 02/2002; 40(3):340-8. · 3.48 Impact Factor
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    ABSTRACT: To assess whether the capital investment required by advances in radiological technology is offset by savings in the direct costs of diagnostic services. Meningeoma was used as an indicator case. All meningeoma patients from three study periods were included: Twenty patients in 1976-77 before the introduction of CT, 22 patients in 1984-85 when CT was used and 16 patients in 1992 when MR imaging had replaced CT as the most informative imaging modality. Radiological and other diagnostic investigations, and the hospital stay were identified and cost analyzed. The costs of radiological examinations increased from 293 Euros in 1976-77 to 513 Euros in 1992. The average number of diagnostic examinations per patient decreased from 5.1 in 1976 77 to 2.4 in 1992. The length of hospital stay decreased from 11.5 to 2.7 days and the total costs of the diagnostic work-up decreased to one-third of the original, i.e. from 3423 Euros in 1976-77 to 1282 Euros in 1992. The costs of the radiological examinations rose, but the development of radiological technology simplified the diagnostic practice. The hospital stay drastically decreased. The total costs of diagnostic work-up per patient dropped to one-third of the baseline costs.
    Acta Radiologica 12/2000; 41(6):539-43. · 1.33 Impact Factor
  • J Vilkki, O Surma-aho, A Servo
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    ABSTRACT: This study partly supports the hypothesis that frontal lobe lesions cause impairment of metamemory. Fifty-nine patients with a focal brain lesion and 21 non-brain-damaged patients memorized a 4 X 4 matrix of 16 faces in 6 consecutive trials and predicted the number of locations of faces they would be able to remember before each retrieval. When age-related impairment of learning was adjusted, the patients with right posterior lesions were inferior to the controls and to the patients with right frontal lesions on the total number of correctly placed faces. The patients with right frontal lesions were less accurate than the patients with right posterior lesions or the controls in the prediction of retrieval. The inaccuracy of retrieval prediction in the face test was associated with that in a word-list learning task.
    Neuropsychology 05/1999; 13(2):298-305. · 3.58 Impact Factor
  • J Vilkki, A Servo, O Surma-aho
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    ABSTRACT: The effect of frontal lobe lesions on the accuracy of prediction of recall in a word list learning task was studied. Fifty-nine patients with a focal brain lesion and 21 non-brain-damaged control patients memorized a word list by selective reminding and predicted before each recall trial the number of words they would be able to recall. The patients with left frontal lesions, who were inferior to the patients with right frontal lesions and the control patients in word list recall, overpredicted their recall more than the other brain-damaged patients or the control patients, especially on the 1st trial. The patients with right frontal lesions were less accurate in the prediction of recall than the patients with right posterior lesions or the control patients.
    Neuropsychology 05/1998; 12(2):268-77. · 3.58 Impact Factor
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    ABSTRACT: The aim of this study was to demonstrate that focal frontal lobe lesions and closed head injuries cause a deficit in the deliberate minimizing of dual task decrements that follow when two separate tasks should be done concurrently. In single tasks, subjects counted backwards and cancelled visual targets as quickly and accurately as possible on separate 1 min trials. In the dual task, they were required to do both tasks simultaneously, taking care that performance on neither task would be notably more impaired than on the other, as only the performance showing a larger percentage decrement from the corresponding single task performance was taken into account as the result of the test. Patients with acute closed head injury displayed more pronounced dual task decrement than the controls. This deficit was not secondary to inefficiency on the single tasks but was related to the depth of coma at admission, the acuteness of injury and age. Contrary to expectation, patients with focal frontal lobe lesions or patients with subacute closed head injury did not demonstrate abnormal dual task decrement.
    Neuropsychologia 12/1996; 34(11):1051-6. · 3.48 Impact Factor
  • K Ahola, J Vilkki, A Servo
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    ABSTRACT: The series of 155 patients operated on for a ruptured intracranial arterial aneurysm was examined using typical frontal tests (the Stroop test, word fluency tasks, and a sorting task), as well as a learning and memory test. Patients with frontal infarction were not significantly inferior to patients with non-frontal infarction or to patients with no infarction. Frontal patients, however, were unable to return to work as often as non-frontal patients and more frequently than those with no infarction. These results indicate that the frontal tests used in this study are not selectively sensitive to mainly medial frontal infarctions that follow the rupture of an anterior cerebral artery aneurysm.
    Brain and Cognition 07/1996; 31(1):1-16. · 2.82 Impact Factor
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    ABSTRACT: A series of 53 patients was studied using a battery of tests and a neurobehavioral rating scale on average 4 months after closed-head injury (CHI). Social outcome was assessed 1 year after injury by interviewing a family member. The results supported the hypothesis that tests of flexibility and programming rather than tests of cognitive skills predict psychosocial recovery after CHI. Spatial Learning with Self-Set Goals and Sorting were measures of flexibility and programming. Contrary to expectation, word fluency performance was unrelated to these measures, but was associated with conventional intelligence tests, which did not predict psychosocial recovery. Cognition/Energy deficit on the Neurobehavioral Rating Scale and increased age were useful predictors of poor psychosocial outcome, whereas computed tomography findings or the Glasgow Coma Score were weakly related to the outcome indices. Evidently, cognitive flexibility and mental programming are very important psychological prerequisites of social recovery after CHI.
    Journal of Clinical and Experimental Neuropsychology 07/1994; 16(3):325-38. · 2.16 Impact Factor
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    ABSTRACT: Computed tomography (CT) findings from early (less than 24 hours) and late scan (6 months) after closed-head injury (CHI) were compared to cognitive test scores obtained on an average of 4 months after injury in a consecutive series of 53 patients. The presence of parenchymal lesion was associated with poor test results, indicating cognitive inflexibility and disinhibition of routine response tendencies in novel tasks. These deficits have previously been found to be related in particular to frontal-lobe dysfunction, but the present study did not support the hypothesis that frontal lesion is the principal cause of this impairment in CHI. Parenchymal lesions in the right and left hemisphere were associated with spatial and verbal deficits, respectively. Ventricular enlargement in the late CT was related to cognitive inefficiency, both being strongly associated with age. The results suggest that parenchymal lesion in the early CT is an indicator of diffuse axonal injury, which results in cognitive inflexibility during recovery.
    Journal of Clinical and Experimental Neuropsychology 08/1992; 14(4):518-32. · 2.16 Impact Factor
  • J Ohman, A Servo, O Heiskanen
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    ABSTRACT: A prospective series of 30 patients with a single, angiographically verified aneurysmal subarachnoid hemorrhage (SAH) was studied for the effect of intrathecal thrombolytic therapy with recombinant tissue plasminogen activator (rt-PA) on outcome, angiographic vasospasm, and computerized tomography (CT) findings after surgery. The patients included fulfilled the following criteria: operation was performed by Day 3 after the hemorrhage, CT showed only blood in the basal cisterns, and the patient had a single aneurysm or multiple aneurysms that could be treated surgically at the same operation. The patients were divided into groups of 10, with patients receiving 3, 10, or 13 mg of rt-PA in a single intracisternal injection at the end of the operation. There were no differences between the treatment groups in overall outcome. One patient from the 3-mg rt-PA group developed a postoperative intracerebral hemorrhage, and one patient from the 10-mg rt-PA group had a postoperative epidural hematoma. There was one death in the 13-mg rt-PA group that was caused by inclusion of a segment of pericallosal artery in the clip. In all treatment groups a reduction was observed in the amount of blood seen on the postoperative CT scans compared to the preoperative CT scans. The reduction in SAH grade between the 10-mg and 13-mg rt-PA groups was significant (p less than 0.05). The difference in the severity of angiographic vasospasm between the 3-mg and 13-mg rt-PA groups was also significant (p less than 0.05).
    Journal of Neurosurgery 09/1991; 75(2):197-201. · 3.15 Impact Factor
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    ABSTRACT: We studied adenosine diphosphate-induced platelet aggregation and the associated release of thromboxane B2 in 49 patients with subarachnoid hemorrhage in relation to angiographic vasospasm. Postoperative cerebral angiography was performed less than or equal to 3 (median 1) days after surgery for an aneurysm 5-14 days after subarachnoid hemorrhage. Correspondingly, one sample from each patient was taken within 24 hours either before or after angiography. The occurrence of severe as well as diffuse, moderate, or severe angiographic vasospasm was associated with the presence of delayed cerebral ischemia (p less than 0.05). Patients with diffuse angiographic vasospasm had significantly higher (p less than 0.05) values for thromboxane B2 release than the others, even after adjustment by the clinical grades on admission and before surgery, the timing of surgery, the time from subarachnoid hemorrhage to angiography and blood sampling, and nimodipine therapy. Severe and diffuse angiographic vasospasm were also associated with poor outcome at 1 year (p less than 0.05). Our results suggest that augmented release of platelet thromboxane may be involved in the pathogenesis of vasospasm in large cerebral arteries.
    Stroke 05/1991; 22(4):451-5. · 6.16 Impact Factor
  • J Ohman, A Servo, O Heiskanen
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    ABSTRACT: A total of 213 patients with verified aneurysmal subarachnoid hemorrhage (SAH) of Grades I to III (Hunt and Hess classification) were enrolled in a double-blind placebo-controlled trial to determine the effect of intravenous nimodipine on delayed ischemic deterioration and computerized tomography (CT)-visualized infarcts after SAH and surgery. The administration of the drug or matching placebo was started immediately after the radiological diagnosis of a ruptured aneurysm had been made. Of the 213 patients enrolled in the study, 58 were operated on early (within 72 hours after the bleed: Days 0 to 3), 69 were operated on subacutely (between Days 4 and 7), and 74 had late surgery (on Day 8 or later). Eleven patients died before surgery was undertaken and one was not operated on. A follow-up examination with CT scanning, performed 1 to 3 years after the SAH (mean 1.4 years), revealed no significant differences in the overall outcome between the groups. However, nimodipine treatment was associated with a significantly lower incidence of deaths caused by delayed cerebral ischemia (p = 0.01) and significantly lower occurrence of cerebral infarcts visualized by CT scanning in the whole population (p = 0.05), especially in patients without an associated intracerebral hemorrhage on admission CT scan (p = 0.03).
    Journal of Neurosurgery 02/1991; 74(1):8-13. · 3.15 Impact Factor
  • J Ohman, A Servo, O Heiskanen
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    ABSTRACT: A prospective series of 265 patients with aneurysmal subarachnoid hemorrhage (SAH) of Grades I to III (Hunt and Hess classification) upon admission were evaluated as to neurological outcome and computerized tomography (CT) findings 1 to 3 years (mean 1.4 years) after the SAH and surgery. A total of 73 patients underwent acute surgery (within 72 hours after the bleed: Days 0 to 3), 86 were operated on subacutely (between Days 4 and 7), and 91 had late surgery (on Day 8 or later). Fifteen patients died before surgery was undertaken and another 20 patients died during the follow-up period. A total of 104 patients received nimodipine and the rest of the patients received either placebo (109 patients) or no medication (52 patients). A logistical regression analysis revealed the following prognostic factors for cerebral infarction, in order of importance: the amount of blood on the primary CT scan; postoperative angiographic vasospasm; the timing of the operation; and a history of hypertension. The use of nimodipine was associated with a significant reduction of cerebral infarcts visualized by CT scanning in patients who received intermediate or late surgery. In patients who underwent acute surgery no significant difference between the incidence of cerebral infarcts was observed.
    Journal of Neurosurgery 02/1991; 74(1):14-20. · 3.15 Impact Factor
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    ABSTRACT: Eighteen patients clinically suspected of having acoustic neurinoma were studied in both orbitomeatal and clivoaxial (CA) (the plane perpendicular to clivus) CT scanning planes during the same sessions. On the CA cuts there were highly significantly less (p less than 0.001) artifacts. Also, the tentorium was highly significantly (p less than 0.001) better visualized on the CA cuts. CA cuts could be recommended in cases when artifacts disturb the diagnostics of posterior fossa pathology or when detailed topographic information about pathologic anatomy round the tentorium is needed.
    Röntgen-Blätter; Zeitschrift für Röntgen-Technik und medizinisch-wissenschaftliche Photographie 01/1991; 43(12):539-42.
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    ABSTRACT: A series of 83 patients was examined with a battery of cognitive tests, a clinical interview, and computed tomography 1 year after surgery for a ruptured intracranial aneurysm. Disability on the Glasgow Outcome Scale (33%), failure to return to work (25%), impaired social relations (25%), and subjective or clinical mental impairment (56%) were found to be related to each other and to poor performance on cognitive tests, especially to verbal impairments in patients with left lateral infarctions and to memory deficits and cognitive inflexibility in patients with frontal medial infarctions. Furthermore, cognitive deficits and poor outcome were associated with diffuse brain damage. Depression and anxiety were unrelated to test performances, but were frequently reported by patients with right lateral infarctions.
    Neurosurgery 05/1990; 26(4):579-84; discussion 584-5. · 2.53 Impact Factor
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    ABSTRACT: Histological anaplasia, found in up to 10% of meningiomas, is an important prognostic sign as it is associated with increased recurrence rate and volume growth rate. We studied in retrospect a series of 230 primary intracranial meningiomas to discover whether histological anaplasia can be reliably foreseen in CT scans and angiograms. 205 meningiomas were histologically benign, and 25 meningiomas were classified as malignant (atypical or anaplastic), with either incipient (20) or overt (5) signs of anaplasia. Of ten CT parameters tested, three were associated significantly more often with malignant meningiomas: nodular contour (58.3% vs 26.7%), cysts (20.0% vs 4.4%) and absence of calcifications (92% vs 65.3%); none of these parameters was an absolute sign of anaplasia. 'Mushrooming', previously regarded as a definite sign of malignancy, was seen in 9% of benign meningiomas and in 21% of malignant ones. In angiography, no apparent differences between benign and malignant meningiomas were seen. The conclusion is that it is not possible to distinguish malignant meningiomas from benign ones with CT or angiography.
    Neuroradiology 02/1990; 32(2):94-7. · 2.70 Impact Factor
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    ABSTRACT: A consecutive series of 118 patients operated on for ruptured intracranial arterial aneurysms was studied. Ninety-six of them could be adequately examined with a battery of psychological tests and computed tomographic scans 1 year after a subarachnoid hemorrhage. Seventeen orthopedic control patients with no history of brain damage were also tested. The pattern of cognitive deficits was strongly related to the findings on the computed tomographic scans. Patients with left lateral infarctions had deficits on performances requiring verbal efficiency, including memory and classification tasks, whereas patients who had right lateral infarctions were poor on a visuoconstructional task (the copying of Rey's Figure). These deficits were pronounced when lateral infarction was associated with diffuse brain damage. Patients with frontal medial infarctions had low scores on memory tests; the inefficiency in verbal fluency, categorical reasoning, and memory was related to diffuse brain damage. The patients who had no infarctions did not differ significantly from the control group. Cognitive impairments after left lateral and frontal medial infarctions, as well as diffuse brain damage, correlated with the Glasgow Outcome Scale.
    Neurosurgery 09/1989; 25(2):166-72. · 2.53 Impact Factor
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    J Vilkki, K Poropudas, A Servo
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    ABSTRACT: The relationship of memory and intelligence test performances to coma duration was studied in 51 head injured patients who had not been operated on for intracranial haematoma. Memory defect was related to coma duration, and was not secondary to impaired perceptual or conceptual analysis of the material to be remembered.
    Journal of Neurology Neurosurgery & Psychiatry 12/1988; 51(11):1452-4. · 4.92 Impact Factor
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    ABSTRACT: Out of 936 primary intracranial meningiomas, 94.3% were histologically benign (grade I), 4.7% atypical (grade II), and 1.0% anaplastic (grade III); one recurrence was sarcomatous (grade IV). Meningiomas with histologic anaplasia (grades II-IV) occurred in 12% of the men, but only 4% of the women. Only 26% of atypical or anaplastic meningiomas appeared completely innocent on a computed tomography scan. Angiograms, usually showing a meningeal feeding artery, suggested meningioma when computed tomography scans did not. At 5 years after complete removal, the recurrence rate was only 3% (21% at 25 years) for benign meningiomas, but 38% for atypical ones, and 78% for anaplastic ones. The median times to recurrence were 7.5, 2.4, and 3.5 years, respectively. In spite of postoperative radiotherapy, four of five anaplastic meningiomas recurred.
    Surgical Neurology 04/1986; 25(3):233-42. · 1.67 Impact Factor
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    ABSTRACT: A randomized double-blind study with iohexol and metrizamide in cervical myelography was performed in 100 patients. The concentration of the contrast medium was 240 mg I/ml. The image quality was equal with both contrast media. Forty-two per cent of the patients receiving iohexol had side effects (headache 22%, nausea 6%, vomiting 2% and mental reactions 6%), in contrast to 80 per cent of the patients receiving metrizamide (headache 56%, nausea 34%, vomiting 24% and mental reactions 26%). The majority of side effects appeared within 6 hours after injection of contrast medium. Two patients had a late onset of symptoms - one in each group. Once appearing, the side effects tended to be equally severe.
    Acta radiologica. Supplementum 02/1986; 369:528-31.
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    ABSTRACT: At operation, 21 meningeal intracranial hemangiopericytomas resembled meningiomas, but differed histologically. They were frequently attached to sinuses, occipitally located, bled profusely at operation, and had a higher risk of recurrence and metastasis. Specific preoperative diagnosis is possible: computed tomography scan showed a meningiomalike tumor, which on the angiogram looked malignant and highly vascular. Two tumors showed a malignant growth pattern on computed tomography scan, "mushrooming." After a radical removal, three patients have lived for more than 10 years without recurrence; two of them were irradiated postoperatively. Three recurrent tumors were treated with radiotherapy only; one responded favorably.
    Surgical Neurology 04/1985; 23(3):227-36. · 1.67 Impact Factor

Publication Stats

917 Citations
104.75 Total Impact Points

Institutions

  • 1978–2002
    • Helsinki University Central Hospital
      • • Department of Neurosurgery
      • • Department of Radiology
      • • Department of Orthopaedics and Traumatology
      Helsinki, Province of Southern Finland, Finland
  • 1978–1986
    • University of Helsinki
      • Department of Pathology
      Helsinki, Province of Southern Finland, Finland