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Biomedical subjects

P Nakstad

Publications and source records attributed to P Nakstad.

At least 19 recordsLinked to original sources
PubMed1992

Regional cerebral blood flow after long-term exposure to carbon disulfide.

Sixteen former rayon viscose workers were investigated four years after the exposure to carbon disulfide was discontinued. Median age was 58 years (range 43-65 years), median exposure time was 17 years (range 10-35 years). Encephalopathy was diagnosed in altogether 14 workers. To further explore pathophysiological mechanisms, cerebrovascular investigations were employed. Doppler ultrasound examination of the precerebral vessels in 15 workers showed a slight stenosis of the left internal carotid artery in one. Regional cerebral blood flow investigation (rCBF) with single photon emission computerized tomography (SPECT) with Xenon-133 gas was performed in 14. There was no significant difference from a control group. Regional side-to-side asymmetries beyond reference limits were demonstrated in eight workers. The abnormalities were modest, but may indicate a tendency toward focal blood flow disturbances in workers with long-term exposure to carbon disulfide.

Adult↗
PubMed1991

[Spontaneous dissection of the internal carotid artery].

Spontaneous dissection of the internal carotid artery is supposed to be a rare condition, but seems to be increasingly diagnosed. The symptoms are protean from unilateral headache, Horners syndrome, tinnitus, to cerebral ischemia and hemipareses. The condition is of unknown incidence and usually affects previously healthy persons. It is nearly always unilateral. The diagnosis is ascertained by characteristic angiographical findings. The prognosis depends on the exhibited symptoms. Three patients seen during the last year at the Department of Neurology at the National Hospital (Rikshospitalet) are presented, together with a brief survey of symptomatology, diagnosis, prognosis and treatment.

Adult↗
PubMed1991

Chiasmal optic neuritis.

We describe two cases of chiasmal optic neuritis. The presenting symptoms were reduced visual acuity and bitemporal visual field defects. The enlargement of the optic chiasm in the acute stage and normalization after recovery is demonstrated by magnetic resonance imaging (MRI).

Adrenal Cortex Hormones↗
PubMed1990

[Acute intracranial hematomas in full term neonates].

During at two-year period, six full term neonates were operated in order to evacuate large intracranial haematomas. They were all critically ill at the time of surgical intervention, but responded well to neurosurgery. The clinical results after 9-28 months follow-up are very gratifying. When anisocoria with unilateral fixed, dilated pupil, hemiplegia or failure of spontaneous ventilation occurs, there is limited time for diagnostic CT scans and evacuation of the haematoma.

Age Factors↗
PubMed1990

[Torkildsen's operation--50 years later].

Arne Torkildsen performed the first ventriculocisternostomy in 1937. During the last 25 years hydrocephalic patients have been treated with standard ventriculoatrial or ventriculoperitoneal shunts. Since pneumoencephalography and ventriculography, have been replaced by CT scanning, often no differentiation is made between communicating and non-communicating hydrocephalus. Today we realize that most shunted individuals become shunt-dependent for the rest of their lives. During a two year period we performed eight ventriculocisternostomies after aqueduct obstruction had been proven by ventriculography or by combined CT and magnetic resonance studies. In five of the patients this gave a satisfactory long term result. Since this procedure does not lead to serious cardiopulmonary complications nor overdrainage, the Torkildsen procedure is still a good alternative to ventriculoperitoneal or ventriculoatrial shunts in patients with proven non-communicating hydrocephalus.

Adolescent↗
PubMed1990

Carbon disulfide exposure and neurotoxic sequelae among viscose rayon workers.

In Norway's only viscose rayon plant, carbon disulfide (CS2) concentrations in ambient air usually were between 30 and 50 mg/m3 during the first 23 years of production. From 1970/1971 until the factory was closed in 1982, corresponding values were 10-25 mg/m3. Through all of these years, high peak exposures of CS2 and H2S occurred. In 1986, 16 of the 24 men still at work in 1982 and with at least 10 years' experience in the spinning room agreed to participate in this study. Clinical neurological examination demonstrated abnormalities in 15; neuropsychological tests showed impairments of probable organic origin in 14. Thirteen had cerebral atrophy demonstrated by cerebral computed tomography (CT). Electromyography (EMG) was abnormal in six, neurography in 11. Regional cerebral blood flow measurements indicated flow asymmetries in eight, whereas Doppler investigation of the extracranial carotid and vertebral arteries, electroencephalography (EEG), and evoked response investigations were mostly normal. Based on these results and the exposure data, a diagnosis of CS2-induced encephalopathy was reached in eight workers; another six had an encephalopathy in which CS2 exposure was regarded as a partial cause. Correspondingly, seven had a neuropathy probably caused by CS2 exposure alone; in three others, CS2 was found to be the partial cause of a neuropathy. This indicates that long-term, relatively moderate exposure to CS2 in association with high peak exposures to CS2 and H2S involves a substantial risk of developing neurotoxic disease.

Adult↗
PubMed1990

Haemodynamic aspects of clinical cerebral angiography. Concurrent two vessel monitoring using transcranial Doppler ultrasound.

To overcome the technical limitations which have precluded noninvasive Doppler ultrasound in investigation of rapid cerebral haemodynamic responses in two cerebrovascular beds at the same time, we have modified a commercial 2 MHz pulsed Doppler instrument with online spectrum analysis. Two probes are activated intermittently, recording eight averaged Doppler-shifted spectra from each probe sequentially. Concurrent recordings of blood velocity in both middle cerebral arteries were performed during 25 selective iohexol carotid angiography runs in 13 patients with near normal cerebral vasculature. The technique permitted the differentiation between the specific responses confined to the recipient vascular bed, and the general responses occurring in remote brain areas as well. The specific response to iohexol was biphasic; a significant decrease in blood velocity occurred less than 4 s after the bolus entry, probably due to the high viscocity of iohexol. Between 4 and 12 s. blood velocity was significantly increased, reflecting the cerebrovascular response to hypertonic solutions. The blood velocity on the opposite side increased from less than 4 s through 45 s after iohexol. This concurs with studies using electromagnetic flowmetry, and suggests that these general responses are elicited by anxiety, discomfort and pain. Thus, no general responses were seen during angiography under general anaesthesia. Eight patients investigated during catheter flushing with normal saline showed a biphasic specific response reciprocal to that due to iohexol. A significant blood velocity peak occurred less than 4 s after the bolus entry, followed by a decrease between 4 and 60 s. The saline injections produced no pain and evoked no significant general response.

Adolescent↗
PubMed1989

Cerebral vasospasm diagnosis by means of angiography and blood velocity measurements.

We investigated 76 patients with known subarachnoid haemorrhage (SAH) in order to compare the results of angiography and non-invasive Doppler recordings of cerebral artery blood velocity in the diagnosis of cerebral vasospasm. One radiologist and one neurovascular surgeon assessed angiographic spasm visually on a four-level scale. The radiologist's ratings were the term of reference for the study. When there was angiographic spasm of the middle cerebral artery (MCA), the MCA blood velocity was higher and the blood velocity in the distal extracranical internal carotid artery (ICA) was lower than when MCA spasm was scored as absent. Analysis by Kappa statistics, a measure for the agreement between two independent judges with correction for random coincidence, revealed moderate agreement between angiographic spasm and the absolute MCA blood velocity (Kappa = 0.47). However, there was substantial agreement (Kappa = 0.64) between angiographic spasm and the index calculated from dividing the blood velocity in the MCA (VMCA) by the blood velocity in the ipsilateral ICA (VICA). The results indicate that this VMCA/VICA index gives more appropriate information on MCA spasm. Congenitally asymmetric circles of Willis with one wide dominant ACA showed normal blood velocities. In asymmetry induced by vasospasm, the diameter of the major ACA was normal or even reduced, and the blood velocity was significantly elevated. Hence, the agreement between blood velocity recordings and angiographic findings was substantial (Kappa = 0.64) when considering together the findings from both sides of the anterior circle of Willis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Cerebral vasospasm after subarachnoid haemorrhage investigated by means of transcranial Doppler ultrasound.

Measurements of flow velocity in defined segments of the basal cerebral arteries can be obtained through the intact adult skull using 2 MHz pulsed Doppler ultrasound. We compared flow velocity in these vessels with findings from 56 cerebral angiographies obtained in 51 patients at from day 1 to day 21 after subarachnoid haemorrhage (SAH). The diameter of the proximal segment of the middle cerebral, anterior cerebral, and posterior cerebral arteries (MCA, ACA, and PCA, respectively) were measured from anteroposterior films produced in one angiographic laboratory. In patients investigated on day 1-2, the median MCA diameter was 2.8 mm with range 2.3-3.4 mm. The median flow velocity was 56 cm/s, range 36-88 cm/s (within normal limits). There was a clear inverse relationship between the MCA diameter and MCA flow velocity. Eleven of the 13 MCA's having diameter 1.5 mm or less showed flow velocity in excess of 140 cm/s. This seems a useful limit to diagnose pronounced MCA spasm (50% diameter reduction) with this method. Further clues to the severity of MCA spasm were obtained from the ratio calculated dividing the MCA flow velocity by the flow velocity in the ipsilateral, extracranial internal carotid artery (ICA), since spasm probably does not involve the neck vessels. This ratio was from 1.1 to 2.3, median 1.7 at day 1-2, but rose to over 10 in patients with the most severe MCA lumen narrowing. The PCA flow velocity was inversely related to the PCA diameter. Assessment of ACA spasm requires considering findings from both hemispheres combined, since the two proximal ACA's usually anastomose through the anterior communicating artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Myelography with iohexol (Omnipaque); a clinical report with special reference to the adverse effects.

One thousand myelographies (370 cervical, 77 thoracic and 553 lumbar examinations) with iohexol (Omnipaque) were performed in 922 patients. No convulsions were seen. Transient hallucinations were reported in one patient. Headache occurred in 38%. The highest frequency of headache (52%) was reported following cervical myelography with lumbar puncture technique, placing the patient horizontally after the examination. The lowest frequency (20%) occurred following cervical myelography with the C1-C2 puncture technique, placing the patient in bed with the head end elevated 20 degrees. Lumbar myelography was performed on an out-patient basis in 243 patients. The frequency of headache was slightly higher (49%) in this group than in the other lumbar myelography patients (34-44%), but no serious complications were seen.

Adolescent↗
PubMed1988

Neurological examination, computerized tomography, cerebral blood flow and neuropsychological examination in workers with long-term exposure to carbon disulfide.

Sixteen males, formerly exposed to carbon disulfide (CS2) for at least 10 years (mean 20 years), were administered a neurological examination, cerebral computerized tomography (CT), regional cerebral blood flow (rCBF) examination and neuropsychological examination. The clinical neurological examination revealed abnormalities in 15; cerebral CT showed signs of atrophy in 13; and neuropsychological examination indicated brain organic changes in 13. With the rCBF examination, slight abnormalities were found in 8. The findings indicate that long-term exposure to CS2 involves a risk of developing toxic encephalopathy, demonstrable on both neurological and neuropsychological examination. Furthermore, structural changes in the brain may be demonstrable by cerebral CT.

Brain↗
PubMed1987

Myelographic findings in cervical spines without degenerative changes. Special reference to sagittal diameter of the dural sac.

One hundred cervical myelographies in patients without degenerative changes on plain radiographs were evaluated. Pathologic changes were seen in 75 patients, most of them with congenital spinal canal stenosis and dural sac stenosis. Normal values for sagittal diameter of the dural sac from C2 to C6 were established. It was found that a quotient less than 0.9 between the sagittal diameter of the spinal canal and the midsagittal diameter of the vertebral body indicated congenital stenosis. It is concluded that plain radiographs of the cervical spine are unreliable in predicting the diagnostic value of cervical myelography.

Adolescent↗
PubMed1987

Secondary retinal detachment interpreted as a part of uveal melanoma by CT-scan.

Four patients with histologically verified uveal melanomas were examined with computed tomography (CT) scan. Ophthalmoscopy revealed a sharply deliminated tumour surrounded by a secondary retinal detachment. The clinically calculated size of the tumours corresponded well with the histological specimens. The CT-scan indicated a greater size of the tumours. The discrepancies were due to difficulties in differentiation between the tumour tissue and the subretinal fluid which have almost identical CT-numbers. By combining axial and coronal views it was possible to distinguish the tumour from the secondary retinal detachment.

Adult↗