Biomedical subjects

M M Haglund

Publications and source records attributed to M M Haglund.

35 records · Page 2Linked to original sources

PubMed1994

Neuronal activity in human lateral temporal cortex during serial retrieval from short-term memory.

Neuronal activity was recorded extracellularly from 20 populations in the lateral cortex of the left anterior temporal lobe of 11 patients undergoing awake craniotomy for epilepsy, during an input-distraction-retrieval measure of recent verbal memory that also included two later successive retrievals of the same information after additional distracting tasks. Changes in activity were determined for each 1 sec epoch in three major comparisons: (1) the same visual cues used for naming an input to recent memory, naming without a memory component, and a spatial matching task; (2) memory input (MI), distraction (S), and initial cued retrieval (R1) from memory, where object naming was the input to memory and naming of other objects the distractors; (3) initial retrieval (R1) and the two subsequent serial retrievals of the same information (R2, R3). Control comparisons were also made with serial naming and viewing of blank slides, and repeated naming of the same objects. In comparison 1, 13 of the 20 populations showed consistently increased activity during memory input ("memory units"); two others showed changes during language measures. In comparison 2, a significant proportion of all 20 populations, and the 13 memory units considered alone showed increased activity in initial epochs of MI and R1, confirming earlier findings of increased lateral temporal neuronal activity at memory entry and initial retrieval. In comparison 3, a significant proportion of the memory units showed increased activity in early epochs of R1 and decreased activity in late epochs of R3. This decrease in populations with increased activity at R1 was also evident when R1 was compared to R2 or R2 to R3.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Dissociation of cortical and single unit activity in spoken and signed languages.

Based on stroke and other lesion data, the cortical organization of sign language has been shown to be in the verbal language-dominant hemisphere. However, finer detail of the cortical organization of sign language is not readily available. Intraoperative cortical mapping of spoken and American Sign Language (ASL) was performed in a hearing patient proficient in ASL undergoing an awake operation for intractable epilepsy. We found the dissociation of essential cortical language sites for spoken and signed languages, the relationship of these sites to the interpretation of ASL, and the importance of the anterior temporal lobe in the language-dominant hemisphere for proper ASL handshapes. Single unit recordings in the anterior temporal lobe, at a site later identified to be important in handshape formation, showed sustained activity during naming with superimposed increases in activity during overt speech.

Adult↗

PubMed1993

Thoracic disc disease: experience with the transpedicular approach in twenty consecutive patients.

TWENTY CONSECUTIVE PATIENTS were treated for symptomatic thoracic disc herniation with the transpedicular approach. Most patients had severe, incapacitating local or radicular pain. Myelopathy was uncommon as magnetic resonance imaging allowed an early diagnosis. Computed tomography, after myelography, provided further information necessary for surgical planning. Three patients had disc disease at two levels. Nine central and 14 lateral disc herniations were found. Disc calcification or an associated osteophyte was identified in six instances. Although the size of the disc herniation correlated with the amount of cord compression, no radiological features were found to be correlated with neurological function. The transpedicular approach was used in all patients. New curettes, specifically designed for the procedure, allowed the removal of all discs, including central and calcified fragments. A modified arthroscope was used to confirm neural decompression in some instances. One year after surgery, all 20 patients were significantly improved and 8 patients were asymptomatic. Apart from the duration of the symptoms, no other factors were found to affect outcome. The findings suggest that the prognosis of thoracic disc herniation is excellent if the disease is recognized early. The transpedicular approach, using curettes specifically designed for the procedure, can be an effective and safe method of surgical decompression in carefully selected patients.

Adult↗

PubMed1993

Optical imaging of bipolar cortical stimulation.

In order to better understand the degree of cortical activation that occurs during bipolar surface stimulation, the authors stimulated monkey visual cortex while monitoring the degree of activation with optical imaging. Optical imaging of intrinsic signals in monkey visual cortex during visual stimulation resulted in functional maps of ocular dominance and orientation selectivity. After functional maps of ocular dominance and orientation preference were obtained, bipolar surface stimulation was applied to activate just the cortical areas around the bipolar electrodes. Graded responses to changes in the stimulation intensity and duration were found. These findings demonstrate the reliability of bipolar cortical surface stimulation in localizing functional regions of cortex. The area of activation, at least in the region around the bipolar stimulating electrodes, did not appear to activate nearby ocular dominance columns or orientation patches. Intraoperative bipolar surface stimulation continues to be a consistently reliable technique for localizing rolandic cortex and essential language sites.

Animals↗

PubMed1993

Low-grade gliomas associated with intractable epilepsy: seizure outcome utilizing electrocorticography during tumor resection.

Adults and children with low-grade gliomas often present with medically refractory epilepsy. Currently, controversy exists regarding the need for intraoperative electrocorticography (ECoG) to identify and, separately, resect seizure foci versus tumor removal alone to yield maximum seizure control in this patient population. Forty-five patients with low-grade gliomas and intractable epilepsy were retrospectively analyzed with respect to preoperative seizure frequency and duration, number of antiepileptic drugs, intraoperative ECoG data (single versus multiple foci), histology of resected seizure foci, and postoperative control of seizures with or without antiepileptic drugs. Multiple versus single seizure foci were more likely to be associated with a longer preoperative duration of epilepsy. Of the 45 patients studied, 24 were no longer taking antiepileptic drugs and were seizure-free (mean follow-up interval 54 months). Seventeen patients, who all had complete control of their seizures, remained on antiepileptic drugs at lower doses (mean follow-up interval 44 months); seven of these patients were seizure-free postoperatively, yet the referring physician was reluctant to taper the antiepileptic drugs. Four patients continued to have seizures while receiving antiepileptic drugs, although at a reduced frequency and severity. In this series 41% of the adults versus 85% of the children were seizure-free while no longer receiving antiepileptic drugs, with mean postoperative follow-up periods of 50 and 56 months, respectively. This difference was statistically significant (p = 0.016). Therefore, based on this experience and in comparison with numerous retrospective studies involving similar patients, ECoG is advocated, especially in children and in any patient with a long-standing seizure disorder, to maximize seizure control while minimizing or abolishing the need for postoperative antiepileptic drugs.

Adolescent↗

PubMed1993

Extratemporal resective surgery for epilepsy.

Extratemporal resections were the most common early operations for epilepsy. This area is in need of further investigations, however, as relatively little progress has been made in management of these cases. The surveys from the Palm Desert Conferences on extratemporal resections with at least 1 year follow-up indicate that of the 825 patients operated between 1949 and 1984, 43.2% were said to be seizure free, 27.8% improved, and 29.1% not improved. Between 1986 and 1990, 768 patients underwent extratemporal resections, with 44.5% seizure free, 35.7% improved, and 19.8% not improved. Thus, there has not been a major improvement in the seizure-free outcomes, although more patients are undergoing surgical treatment and there are increases in the "improved" category. Moreover, these results are worse than those for temporal resections reported by the same surveys. As is apparent from this article, extratemporal epilepsies are very heterogeneous. The techniques of electrophysiology that have been so successful with temporal lobe epilepsy seem to be less so with many extratemporal epilepsies, however, suggesting that improved outcomes for those conditions especially may depend on new techniques, such as those based on imaging.

Brain Mapping↗

PubMed1993

Seizure outcome in patients undergoing temporal lobe resections for epilepsy.

This article reviews the results of surgical treatment of temporal lobe epilepsy based on retrospective reviews: more recent surveys from 91 centers on the outcomes from the surgical treatment of epilepsy and preliminary data from the authors' institution's 5-year retrospective review of nearly 100 surgical patients matched to medically treated epileptics. Surgical outcomes from resections in other areas, including extratemporal resections, and the efficacy of lesionectomy versus epilepsy surgery for structural lesions are detailed elsewhere in this issue.

Epilepsy, Temporal Lobe↗

PubMed1992

Optical imaging of epileptiform and functional activity in human cerebral cortex.

Optical imaging of animal somatosensory, olfactory and visual cortices has revealed maps of functional activity. In non-human primates, high-resolution maps of the visual cortex have been obtained using only an intrinsic reflection signal. Although the time course of the signal is slower than membrane potential changes, the maximum optical changes correspond to the maximal neuronal activity. The intrinsic optical signal may represent the flow of ionic currents, oxygen delivery, changes in blood volume, potassium accumulation or glial swelling. Here we use similar techniques to obtain maps from human cortex during stimulation-evoked epileptiform afterdischarges and cognitively evoked functional activity. Optical changes increased in magnitude as the intensity and duration of the afterdischarges increased. In areas surrounding the afterdischarge activity, optical changes were in the opposite direction and possibly represent an inhibitory surround. Large optical changes were found in the sensory cortex during tongue movement and in Broca's and Wernicke's language areas during naming exercises. The adaptation of high-resolution optical imaging for use on human cortex provides a new technique for investigation of the organization of the sensory and motor cortices, language, and other cognitive processes.

Brain Mapping↗

PubMed1992

Intraventricular hemorrhage in blunt head trauma: an analysis of 43 cases.

Before the advent of computed tomography, intraventricular hemorrhage (IVH) from any source was thought rare and invariably fatal. Although intraventricular blood is readily identifiable with computed tomography, there has been little systematic study of its significance in blunt head trauma. Forty-three patients with traumatic IVH were prospectively identified in 1 year at Harborview Medical Center (University of Washington). Most were victims of motor vehicle accidents and suffered severe head injuries. IVH occurred alone in two patients; superficial contusions and subarachnoid hemorrhage were the most common associated finding. Blood was present in only one or both lateral ventricles in 25 patients; only the 3rd or 4th ventricles in 4 and all ventricles in 14 instances. There were 3 intracerebral hematomas and 14 basal ganglion hemorrhages. All of the former and half of the latter communicated with the adjacent lateral ventricle. Extra-axial hematomas appeared more common when only the lateral ventricles were involved, whereas corpus callosum or brain-stem hemorrhage appeared more likely when all the ventricles were involved. Acute hydrocephalus was rare, and ventricular drainage was needed in only four cases. Intracranial pressure (ICP) was elevated (> 15 mm Hg) in 46% of patients. The amount of IVH was related inversely with the Glasgow Coma Scale, but not with increased ICP. The presence of IVH indicated a poor outcome, with only half of the patients being independent at a 6-month follow-up. Poor outcome was associated with increasing age, low admission Glasgow Coma Scale, the presence of space occupying lesions if only the lateral ventricles were involved, and hemorrhage in all four ventricles.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of Daily Living↗

PubMed1992

Changes in gamma-aminobutyric acid and somatostatin in epileptic cortex associated with low-grade gliomas.

The role of specific neuronal populations in epileptic foci was studied by comparing epileptic and non-epileptic cortex removed from patients with low-grade gliomas. Epileptic and nearby (within 1 to 2 cm) non-epileptic temporal lobe neocortex was identified using electrocorticography. Cortical specimens taken from four patients identified as epileptic and nonepileptic were all void of tumor infiltration. Somatostatin- and gamma-aminobutyric acid (GABAergic)-immunoreactive neurons were identified and counted. Although there was no significant difference in the overall cell count, the authors found a significant decrease in both somatostatin- and GABAergic-immunoreactive neurons (74% and 51%, respectively) in the epileptic cortex compared to that in nonepileptic cortex from the same patient. It is suggested that these findings demonstrate changes in neuronal subpopulations that may account for the onset and propagation of epileptiform activity in patients with low-grade gliomas.

Brain Neoplasms↗

PubMed1991

Symptomatic cerebral vasospasm following tumor resection: report of two cases.

The authors report two cases of symptomatic cerebral vasospasm following resection of an acoustic neuroma and a left sphenoid wing meningioma. Vascular spasm was documented by transcranial Doppler and angiography studies. Both patients responded to hypervolemic therapy. Possible mechanisms contributing to this rare complication are discussed.

Adult↗

PubMed1991

Resection of intrinsic tumors from nondominant face motor cortex using stimulation mapping: report of two cases.

We report two right-handed patients who underwent resection of intrinsic glial tumors from the nondominant hemisphere, face motor cortex. Both patients underwent preoperative assessment with computed tomography and magnetic resonance imaging localizing the tumor in the inferior region of the Rolandic cortex. With the patients under general anesthesia and without muscular paralysis, the tumor volume was determined by intraoperative ultrasound and resective surgery accomplished with the aid of cortical and subcortical stimulation mapping techniques. Radical resection of the tumor from the face motor cortex was achieved in both patients. A transient contralateral facial weakness and apraxia were noted in each patient, and this resolved within 6 to 8 weeks following surgery. Removal of intrinsic tumors involving the nondominant face motor cortex may be safely achieved using brain mapping techniques to localize inferior Rolandic cortex and avoid resection of the hand motor cortex and descending subcortical motor pathways. Permanent disability will be prevented due to the bilateral representation of face motor function at the neocortical level. However, due to language localization in cortical zones contiguous with the dominant hemisphere, face motor cortex, we do not recommend resection of this region.

Adolescent↗

PubMed1990

Role of Na-K pump potassium regulation and IPSPs in seizures and spreading depression in immature rabbit hippocampal slices.

1. Using the immature (8-12 days postnatal) rabbit hippocampal slice preparation, we investigated regional extracellular potassium concentration [( K+]o) changes that occur during spontaneous and evoked spreading depression (SD) episodes. We report here a difference between the CA1 and CA3 cell populations in the immature hippocampus with regard to 1) resting [K+]o, 2) magnitude of the [K+]o change during seizurelike events and SDs, and 3) susceptibility to SD episodes. Experiments were also performed to elucidate the roles that the Na-K pump and synaptic inhibition play in controlling SD onset, duration, and recovery. We demonstrated a major role for potassium regulation by the Na-K pump and a lesser modulatory role for inhibitory postsynaptic potentials (IPSPs) in preventing SD in the CA3 region. 2. Simultaneous intra- and extracellular recordings were made in the CA1 and CA3 regions of the immature rabbit hippocampus during spontaneous or evoked SD, while potassium ion-sensitive microelectrodes (K-ISMs) monitored changes in [K+]o. The CA1 region had 1) a higher frequency of spontaneous SD episodes than CA3, 2) a lower threshold to potassium-triggered SD, 3) a longer duration SD episode, and 4) smaller post-SD membrane potential and [K+]o undershoots (below the original resting membrane potential and resting [K+]o). 3. During the onset of a SD episode in the CA1 region, the local [K+]o rose either before or at the same time as the membrane potential depolarization. 4. In the CA3 region, spontaneous ictallike events consisting of tonic cell depolarization with repetitive activity followed by clonic afterdischarges were more likely to occur than SD episodes. During these ictallike episodes, [K+]o rose above the 10- to 12-mM ceiling level reported for adult CNS tissue during seizures. Increases in [K+]o evoked by repetitive stimulation were regulated at a lower level in CA3 (average [K+]o rise to 11.4 mM) than in CA1 (average [K+]o rise to 18.3 mM). 5. In CA3, bath application of 10 microM bicuculline or 3.4 mM penicillin did not change the frequency of spontaneously occurring SDs or the SD response threshold to local pressure ejection of 2 M KCl. However, blockade of IPSPs did lead to lower thresholds for SD or seizurelike episodes elicited by stimulation of the mossy fibers. 6. A single application of ouabain (10 microM) to CA3 by local pressure ejection caused a slow rise in local [K+]o measured with K-ISMs. The ouabain treatment also increased the frequency of spontaneous postsynaptic potential activity and decreased the amplitude and duration of CA3 pyramidal cell afterhyperpolarizations (AHPs).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1988

Neuronal activity in human lateral temporal cortex related to short-term verbal memory, naming and reading.

Extracellular microelectrode recordings were obtained from lateral temporal cortex that was subsequently resected in patients undergoing craniotomies under local anaesthesia for treatment of medically intractable epilepsy. During these recordings patients performed visually presented measures of overt and silent naming and word reading, short-term verbal memory and a control task requiring matching of angles. These measures were designed so that the same visual stimuli elicited language, short-term memory or spatial responses. Statistically significant changes within and between these various measures were identified. Technically satisfactory recordings were obtained from 17 populations reflecting activity predominantly from 1 neuron, in 13 patients. Two populations demonstrated no significant changes in any measured functions. Only 1 population showed changes suggesting a relation to visual perception. Four populations in or adjacent to the superior temporal gyrus altered activity with overt speech. Four other populations in the anterior temporal lobe altered activity during silent, but not overt speech. Some relation to language or memory was established for 13 of the 17 populations: 1 altered activity during reading alone, 6 during memory alone, and 6 to both. Most of the recording sites showing these language and memory changes were not essential for those functions based on surface electrical stimulation mapping. Thus the area of temporal lobe that participates in language and memory, as indicated by changes in neuronal activity, is substantially larger than the areas essential for those functions as determined by stimulation mapping. Within that participatory area, changes related to language were most often an increase in activity sustained throughout the task, a pattern suggestive of mechanisms of selective attention. Changes related to memory most often included a sustained increase in activity at the time of entry of information into memory, and again at retrieval, with decreased activity during the time the memory was stored. A few neuronal populations demonstrated relative inhibition of activity during the memory task, compared with control measures.

Electric Stimulation↗

PubMed1985

Developmental and regional differences in the localization of Na,K-ATPase activity in the rabbit hippocampus.

Regional differences in Na,K-ATPase activity, and development of Na,K-ATPase activity were examined in rabbit hippocampus using a histochemical marker of enzyme activity. Stratum lucidum of CA3/CA2, corresponding to the mossy fiber terminal field, showed high Na,K-ATPase activity compared to stratum radiatum of CA1. A significant increase in Na,K-ATPase activity was found between 8 and 15 days postnatal. Tissues with limited Na,K-ATPase activity (immature hippocampus, the mature CA1 region) appear particularly prone to seizure-like abnormalities, perhaps reflecting an inability to regulate extracellular potassium.

Animals↗

PubMed1984

Seizure-like spreading depression in immature rabbit hippocampus in vitro.

Study of immature rabbit hippocampus, using the in vitro slice preparation, has revealed seizure-like spreading depression (SD) episodes in tissue from 8-12-day-old animals. These SDs occur both spontaneously and in response to stimulation, and are seen in both extracellular and intracellular recordings. At the cellular level, SDs are similar to epileptiform ictal phenomena in their onset bursts of action potentials, prolonged membrane depolarizations, and afterdischarge bursts. Glial recordings indicate that a large rise in [K+]0 occurs during these SD episodes. Low chloride concentration in the bathing medium facilitates SD occurrence. The immature CA1 region, where inhibition is slow to develop, is more susceptible to SDs than the CA3 region, where inhibitory post-synaptic potentials are potent early in development. These observations suggest that the slice preparation of immature rabbit hippocampus may provide a useful model in which to study epileptiform mechanisms, such as inhibitory efficacy and extracellular potassium clearance, which might be responsible for ictal onset and control.

Animals↗

PubMedDate not supplied

Spontaneous rhythmic synchronous activity in epileptic human and normal monkey temporal lobe.

Intracellular recordings were obtained from neurons in tissue taken from human epileptic temporal lobe and normal monkey hippocampus. Using the in vitro slice preparation, we confirmed that spontaneous rhythmic synchronous events (SRSEs) were predominantly found in cells of mesial temporal lobe. These synaptic-like events appeared to be mediated by a GABAergic mechanism, since they were blocked by bicuculline. An interneuron-like cell type was found which discharged in a burst pattern in parallel with SRSE occurrence in pyramidal neurons. Burst discharges were graded and excitatory postsynaptic potential (EPSP)-triggered; all-or-none paroxysmal depolarizations were extremely rare. These features of SRSE activity suggest that population synchrony in this tissue is largely dependent on local inhibitory interneuronal circuitry. SRSEs were found in normal monkey hippocampus as well as in mesial tissue from human epileptic temporal lobe. This result indicates that SRSEs are not a direct reflection of tissue epileptogenicity. However, the circuitry underlying SRSEs may be important in the determination of tissue seizure susceptibility, since it provides a substrate for cell synchronization.

Animals↗