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R M Kalnins

Publications and source records attributed to R M Kalnins.

28 records · Page 2Linked to original sources
PubMed1990

Hippocampal sclerosis can be reliably detected by magnetic resonance imaging.

Two independent blinded observers reported the preoperative MRIs in a series of 81 consecutive patients with intractable temporal lobe epilepsy who were undergoing temporal lobectomy. We then compared the nature and lateralization of the MRI abnormalities with the pathologic diagnosis and the side of lobectomy. The MRI criteria of hippocampal sclerosis were an increased T2-weighted signal and the signal's confinement to a unilaterally small hippocampus. Imaging was performed in coronal and axial planes, specially orientated along and perpendicular to the long axis of the hippocampal body. We found diagnostic MRI abnormalities in 25 of the 27 cases with pathologically proven hippocampal sclerosis (sensitivity 93%, specificity 86%). In addition, we detected all 13 foreign tissue lesions on MRI. Overall, we detected lateralized lesions on MRI that correctly predicted the side of the epileptogenic temporal lobe in 72 cases (89%), with 2 possible errors. A learning effect in appreciating the relatively subtle MRI changes of hippocampal sclerosis was apparent in our later cases, as shown by an improved correlation between the 2 observers. This study demonstrates that hippocampal sclerosis can be identified on MRI with a high degree of sensitivity and specificity.

Brain Neoplasms↗
PubMed1989

Catecholamine uptake sites in mouse brain: distribution determined by quantitative [3H]mazindol autoradiography.

Because of the importance of the mouse brain catecholamine system in the study of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and because little information is available concerning the chemical neuroanatomy of the mouse, catecholamine uptake sites were mapped in C57 black mouse brain using [3H]mazindol autoradiography. Displacement studies with known dopamine (DA) and noradrenaline (NA) uptake blockers showed that binding in the striatum was entirely to DA uptake sites, while binding in the locus coeruleus was to NA uptake sites only. By using the selective noradrenergic uptake blocker desmethylimipramine (DMI), a complete map of both DA and NA uptake sites was generated. The mesostriatal DA system was the most clearly labelled and uptake sites were seen better in striatal terminals than the substantia nigra. Within the noradrenergic system, highest binding levels were seen over the locus coeruleus, although it was unclear whether these uptake sites were on cell bodies or terminals from the lateral tegmental noradrenergic system. These maps of the catecholamine uptake system in mouse brain provide a baseline for study of newly discovered neurotoxins and ageing processes.

Animals↗
PubMed1989

Limbic P3 potentials, seizure localization, and surgical pathology in temporal lobe epilepsy.

Limbic P3 event-related potentials were recorded from mesial temporal electrodes implanted for presurgical investigation in 70 patients with intractable focal seizures. In 46 (81%) of 57 patients with unilateral temporal lobe epilepsy, the limbic P3 potential was absent or rudimentary ipsilateral to the seizure focus and a robust P3 potential was always elicited from the nonepileptogenic temporal lobe. Bilateral P3 potentials were recorded in 6 patients (10%) with unilateral temporal lobe epilepsy. In the remaining 5 patients in the group with unilateral temporal lobe epilepsy, results showed P3 bilaterally absent (2 patients), P3 present in a unilateral investigation (1 patient), P3 absent contralateral to the seizure focus (1 patient), and technically unsatisfactory recordings (1 patient). Bilaterally absent P3 potentials were noted in 2 patients with bilateral temporal lobe epilepsy. In 6 patients with technically adequate P3 studies and extratemporal seizures, bilaterally present P3 potentials were noted. Sensitivity and specificity of P3 absence as a predictor of an epileptogenic temporal lobe were 87% and 95%, respectively. Tissue specimens of the hippocampus were available in 22 patients (43%). Thirteen hippocampi showed sclerosis, all of which were associated with unilaterally absent P3 potentials. Nine hippocampi were normal (5 patients with the P3 absent, 4 with P3 present). Sensitivity and specificity of an absent limbic P3 as a function of hippocampal pathological findings were 100% and 44%, respectively. Absent limbic P3 potentials in temporal lobe epilepsy thus indicate structural or functional hippocampal abnormality and may add important information in presurgical evaluation with depth electrodes of patients who have temporal lobe epilepsy.

Adolescent↗
PubMed1989

Localization of epileptic foci with postictal single photon emission computed tomography.

Effective surgical treatment of patients with intractable complex partial seizures depends on accurate preoperative seizure focus localization. We evaluated seizure localization with interictal and immediate postictal single photon emission computed tomographic images of cerebral perfusion using technetium-99m-hexamethyl-propyleneamineoxime (99mTc-HMPAO) in comparison with conventional ictal electroencephalographic (EEG) localization. Thirty-two patients with intractable complex partial seizures were studied. The mean delay from seizure onset to injection was 6.3 +/- 5.3 (SD) minutes. Independent blinded observers assessed the scans for interictal hypoperfusion and postictal focal hyperperfusion. Interictal scans alone were unreliable, indicating the correct localization in 17 patients (53%) and an incorrect site in 3 (9%). When interictal and postictal scans were interpreted together, the focus was correctly localized in 23 patients (72%). There was 1 false-positive study, and 8 patients had inconclusive changes, including 2 with inconclusive depth EEG studies. Postictal hyperperfusion was predominantly mesial temporal and frequently associated with hypoperfusion of lateral temporal cortex. Secondarily generalized seizures tended to show focal hyperperfusion less often than complex partial seizures did (Fisher's exact test p = 0.09). Combined interictal and immediate postictal single photon emission computed tomography with 99mTc-HMPAO is a useful noninvasive technique for independent confirmation of electrographic seizure localization. It may provide a suitable alternative to the use of depth electrode studies for confirmation of surface EEG findings in many patients with complex partial seizures.

Adolescent↗
PubMed1987

Regional and temporal effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine on dopamine uptake sites in mouse brain.

When the regional effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on brain dopamine uptake sites in C57 Black mice were studied using [3H]mazindol autoradiography, marked regional differences in effect were seen: the mesolimbic system was less affected than the nigrostriatal tract and within each system the effect was more severe in the terminal fields of the striatum than in the cells of origin. Within the striatum itself there was inhomogeneity of effect, with relative sparing of the dorsomedial aspect compared to the remainder. Complete recovery of [3H]mazindol binding to striatal membranes occurred over 12 months, while dopamine levels recovered more slowly. This supports the concept that MPTP has a highly selective effect within dopaminergic systems and that the initial effect is more pronounced on distal terminals compared to cell bodies. The possibility that recovery of mazindol binding with time may be associated with terminal regrowth needs to be investigated further.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1987

Otocerebral mucormycosis--a case report.

Mucormycosis is an often fatal infection caused by ubiquitous organisms of the order Mucorales. Infection is most commonly seen in the immunocompromised host, particularly in the setting of diabetic ketoacidosis. The most common presentation is with rhinocerebral involvement. We here report a case of otocerebral mucormycosis occurring in an elderly man with maturity onset diabetes who was not acidotic. The unusual site of infection delayed diagnosis until the pons had been invaded by the infecting organism which was demonstrated as a hypodense area on CT scan. Consequently radical excision of infected tissue was not feasible and the patient died. At post-mortem examination there was extensive infection and infarction of the parotid gland, inner ear and pons associated with arterial invasion by the fungus and septic cavernous sinus thrombosis. The case is described to demonstrate the existence of other modes of neurological presentation of mucormycosis apart from the well recognized rhinocerebral form. Early diagnosis is the key to successful therapy.

Aged↗
PubMed1986

The neurochemical and clinical effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in small animals.

The recent discovery that 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) causes a syndrome of Parkinsonism in man and monkey has stimulated the search for a small animal model of Parkinsonism. In this study, MPTP was administered to a series of small animals and observations made on clinical and neurochemical changes. The clinical effects of MPTP in rabbits, guinea pigs, and rats were short lived, and no chronic Parkinsonian syndrome developed. The C57 black mouse, however, although also not showing clinical changes, proved to be an ideal neurochemical model in which to study the effects of MPTP since striatal dopamine levels were reliably reduced to 13% of control values after 4 intraperitoneal injections of 30 mg/kg MPTP. Pathological study of the striatum and substantia nigra in the mouse model failed to show any alteration in neuronal morphology or numbers. Although the effect of MPTP on striatal dopamine lasted for up to 2 weeks after the last MPTP injection, the possibility exists that no neurotoxic effects occur and the observed dopamine depletion is pharmacological only.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1984

Central pontine myelinolysis with widespread extrapontine lesions: a report of two cases.

Two cases of central pontine myelinolysis with extensive extrapontine lesions are described. Both occurred in patients with longstanding quadriplegia in whom severe hyponatraemia, occurring in a setting of respiratory infection, was rapidly corrected with hypertonic saline. The extrapontine lesions resembled those described in extrapontine myelinolysis, but the possibility that an anoxic-ischaemic component may have contributed is discussed. The clinical data in these two cases are consistent with the mounting body of clinical and experimental evidence that disturbances of sodium balance may be an important cause of central pontine and extrapontine myelinolysis.

Adult↗
PubMedDate not supplied

Cerebellar infarction: natural history, prognosis, and pathology.

Using clinical and computed tomography (CT) criteria, an analysis of 2,000 consecutive stroke unit patients from 1977 to 1984 revealed 30 patients with cerebellar infarction. The case fatality rate was 23%, higher than for any other location of brain infarction studied over the same period. Death was most often due to concomitant brainstem infarction. Obstructive hydrocephalus occurred in 4 patients (13%), and in 2 cases diagnosis, facilitated by urgent CT scanning, allowed early surgical intervention that was life saving. Patients who survived the acute phase were followed for an average of 21 months, and over that time 22% sustained further brainstem infarction, representing a 13% stroke rate per year. Over the latter 3 years of the clinical study, an autopsy survey revealed 11 cases of cerebellar infarction that had been clinically unrecognized. None of these died as a direct result of their infarction. Mechanisms of infarction inferred from autopsy included in situ thrombosis, embolism, watershed, and lacunar infarction, with in situ thrombosis being the most common. We conclude that the case fatality rate of cerebellar infarction is greater than of any other form of brain infarction, but it may be reduced by prompt recognition of those patients who will benefit from surgical decompression. In survivors, a high risk of subsequent hindbrain stroke exists. More attention needs to be paid to this entity in terms of early diagnosis and prevention of subsequent stroke.

Aged↗