Human pyramidal to interneuron synapses are mediated by multi-vesicular release and multiple docked vesicles

Classic theories link cognitive abilities to synaptic properties and human-specific biophysical features of synapses might contribute to the unparalleled performance of the human cerebral cortex. Paired recordings and multiple probability fluctuation analysis revealed similar quantal sizes, but 4-times more functional release sites in human pyramidal cell to fast-spiking interneuron connections compared to rats. These connections were mediated on average by three synaptic contacts in both species. Each presynaptic active zone (AZ) contains 6.2 release sites in human, but only 1.6 in rats. Electron microscopy (EM) and EM tomography showed that an AZ harbors 4 docked vesicles in human, but only a single one in rats. Consequently, a Katz's functional release site occupies ~0.012 μm(2) in the human presynaptic AZ and ~0.025 μm(2) in the rat. Our results reveal a robust difference in the biophysical properties of a well-defined synaptic connection of the cortical microcircuit of human and rodents.

Human neuronal changes in brain edema and increased intracranial pressure

Functional and molecular changes associated with pathophysiological conditions are relatively easily detected based on tissue samples collected from patients. Population specific cellular responses to disease might remain undiscovered in samples taken from organs formed by a multitude of cell types. This is particularly apparent in the human cerebral cortex composed of a yet undefined number of neuron types with a potentially different involvement in disease processes. We combined cellular electrophysiology, anatomy and single cell digital PCR in human neurons identified in situ for the first time to assess mRNA expression and corresponding functional changes in response to edema and increased intracranial pressure. In single pyramidal cells, mRNA copy numbers of AQP1, AQP3, HMOX1, KCNN4, SCN3B and SOD2 increased, while CACNA1B, CRH decreased in edema. In addition, single pyramidal cells increased the copy number of AQP1, HTR5A and KCNS1 mRNAs in response to increased intracranial pressure. In contrast to pyramidal cells, AQP1, HMOX1and KCNN4 remained unchanged in single cell digital PCR performed on fast spiking cells in edema. Corroborating single cell digital PCR results, pharmacological and immunohistochemical results also suggested the presence of KCNN4 encoding the α-subunit of KCa3.1 channels in edema on pyramidal cells, but not on interneurons. We measured the frequency of spontaneous EPSPs on pyramidal cells in both pathophysiological conditions and on fast spiking interneurons in edema and found a significant decrease in each case, which was accompanied by an increase in input resistances on both cell types and by a drop in dendritic spine density on pyramidal cells consistent with a loss of excitatory synapses. Our results identify anatomical and/or physiological changes in human pyramidal and fast spiking cells in edema and increased intracranial pressure revealing cell type specific quantitative changes in gene expression. Some of the edema/increased intracranial pressure modulated and single human pyramidal cell verified gene products identified here might be considered as novel pharmacological targets in cell type specific neuroprotection.

Comparison of Clinical Symptoms and Magnetic Resonance Angiographic (MRA) Results in Patients with Trigeminal Neuralgia and Persistent Idiopathic Facial Pain. Medium-Term Outcome after Microvascular Decompression of Cases with Positive MRA Findings

To evaluate whether NC could be demonstrated preoperatively, high-resolution magnetic resonance angiography (MRA) was performed in 287 consecutive patients with TN and persistent idiopathic facial pain (PIFP) on a 0.5-T and a 1-T MR unit. Depending on the clinical symptoms, the TN cases were divided into typical TN and trigeminal neuralgia with non-neuralgic interparoxysmal pain (TNWIP) groups. Microvascular decompression (MVD) was performed in 103 of the MRA-positive cases. The patients were followed up postoperatively for from 1 to 10 years. The clinical symptoms were compared with the imaging results. The value of MRA was assessed on the basis of the clinical symptoms and surgical findings. The outcome of MVD was graded as excellent, good or poor. The clinical symptoms were compared with the type of vascular compression and the outcome of MVD. The MRA image was positive in 161 (56%) of the 287 cases. There were significant differences between the clinical groups: 66.5% of the typical TN group, 47.5% of the TNWIP group and 3.4% of the PIFP group were positive. The quality of the MR unit significantly determined the ratio of positive/negative MRA results. The surgical findings corresponded with the MRA images. Six patients from the MRA-negative group were operated on for selective rhizotomy and no NC was found. Venous compression of the trigeminal nerve was observed in a significantly higher proportion in the background of TNWIP than in that of typical TN on MRA imaging (24.1% and 0.8%, respectively) and also during MVD (31.2% and 1.2%, respectively). Four years following the MVD, 69% of the patients gave an excellent, 23% a good and 8% a poor result. The rate of some kind of recurrence of pain was 20% in the typical TN and 44% in TNWIP group. The rate of recurrence was 57% when pure venous compression was present. The only patient who was operated on from the PIFP group did not react to the MVD. The clinical symptoms and preoperative MRA performed by at least a 1-T MR unit furnish considerable information, which can play a role in the planning of the treatment of TN.

[ENDOSCOPIC REMOVAL OF TUBERCULUM SELLAE MENINGEOMA THROUGH ENDONASAL TRANSSPHENOIDAL APPROACH]

Experiences acquired in our department with endoscope assisted microsurgical transsphenoidal pituitary surgery encouraged us to expanded the endoscopic approach to skull base lesions. The endoscopic endonasal transsphenoidal approach proved to be less traumatic to the traditional microsurgical approaches, yet very effective. The endoscopic transsphenoidal technique was applied in a patient havin anterior skull base tumor. The patient was a 49-year-old woman with several months history of left visual defect. The magnetic resonance (MR) scans of the skull revealed a midline anterior fossa space-occupying lesion measuring 21 x 16 x 22 mm located on planum sphenoidale, tuberculum sellae and intrasellar. The tumor compressed both optic nerves and optic chiasm. Total resection of the tumor was achieved by use of endoscopic transnasal, transsphenoidal technique. This is the first reported case of an anterior fossa meningeoma being treated by an endoscopic transsphenoidal technique in Hungary.

Aortic arch and common carotid artery plaques with soft components pose a substantial risk of cerebral embolization during carotid stenting

OBJECTIVES

A higher rate of embolization is considered a disadvantage of carotid stenting (CAS), when compared with carotid endarterectomy. Plaques in the aortic arch (AA) and the common carotid artery (CCA) may be additional sources of embolization to stented internal carotid plaques during CAS. In this study, we aimed to investigate the relationship between these plaques and intracerebral embolization.

METHODS

We analyzed the occurrence and composition of plaques in the AA and CCA by computed tomography angiography (CTA) in 101 consecutive cases of CAS. Cases of peri-procedural embolization were detected on diffusion-weighted imaging as lesions demonstrating diffusion restriction. We applied the χ(2) and Fisher's exact tests, as well as logistic regression models.

RESULTS

The occurrence of plaques in the AA and CCA was significantly related to the appearance of new diffusion-weighted imaging lesions (p = 0.013 and p = 0.004, respectively). Patients with soft plaques in the AA or CCA had a significantly higher risk of embolization than those without plaques (p = 0.012 and p = 0.006, respectively). In contrast, homogeneously calcified plaques did not pose significantly higher risks.

CONCLUSIONS

Soft plaques in the AA and CCA result in a substantial risk of embolization during CAS. Use of a CTA examination of the AA and the CCA in patients with carotid stenosis may help to select lower-risk patients for CAS.

The role of probabilistic tractography in the surgical treatment of thalamic gliomas

BACKGROUND

Thalamic gliomas represent a great challenge for neurosurgeons because of the high surgical risk of damaging the surrounding anatomy. Preoperative planning may considerably help the surgeon find the most ideal operative trajectory, avoiding thalamic nuclei and important white matter pathways adjacent to the tumor tissue. Thalamic segmentation is a promising imaging tool based on diffusion tensor magnetic resonance imaging. It provides the possibility to predict the relationship of the tumor to thalamic nuclei.

OBJECTIVE

To propose a new tool in thalamic glioma surgery that may help to differentiate between normal thalamus and tumor tissue, making preoperative planning possible and facilitating the choice of the optimal surgical approach and trajectory for neuronavigation-assisted surgery.

METHODS

Four patients with thalamic gliomas preoperatively underwent conventional and diffusion-weighted magnetic resonance imaging conducted on 1.5 T. Subsequently, probabilistic tractography and thalamic segmentation were performed with the FSL Software as preoperative planning. We also present a case when thalamic segmentation was applied retrospectively using preoperative images. All patients went through neuronavigation-assisted surgery (1 partial, 4 subtotal resections).

RESULTS

Surgery performed based on the output of thalamic segmentation caused no deterioration in the neurological symptoms of our patients. Indeed, we noticed improvement in the neurological condition in 3 cases; furthermore, in 2 patients, a concern-free state was achieved.

CONCLUSION

We suggest that thalamic segmentation may be applied successfully and routinely in the surgical treatment of thalamic gliomas.

Post-operative management of primary glioblastoma multiforme in patients over 60 years of age

BACKGROUND AND PURPOSE

Optimal treatment for elderly patients with glioblastoma multiforme is not well defined. We evaluated the efficacy of post-operative radiotherapy with or without concomitant and/or adjuvant temozolomide in patient, aged > or = 60 years to assess survival and identify prognostic factors of survival.

METHODS

A retrospective analysis of overall survival and progression-free survival in patients with newly diagnosed glioblastoma multiforme aged > or = 60 years treated with post-operative radiotherapy with or without temozolomide chemotherapy was conducted at our institutions. Prognostic factors were determined by univariate and multivariate analyses.

RESULTS

Of 75 study participants (54.7% male; median age at first diagnosis, 65.1 years), 29 (38.7%) underwent gross total resection, whereas others underwent partial resection or biopsy only. All but 1 patient received radiotherapy. Twenty patients received concomitant temozolomic e only. Adjuvant temozolomide (1-50 cycles) was administered in 42 patients; 16 received > or = 6 cycles. Median overall survival was 10.3 months. One- and 2-year overall survival rates were 42.6% and 6.7%, respectively. Median progression-free survival was 4.1 months. Radiochemotherapy was generally well tolerated. Median overall survival was 15.3 and 29.6 months for patients who received 6-12 cycles and >12 cycles of adjuvant temozolomide, respectively. There were no significant differences in overall survival between age groups (60-64, 65-69, and > or = 70 years). Adjuvant temozolomide, Karnofsky performance status > or = 70, and additional surgery after progression were significant prognostic factors of longer overall survival (p<0.05).

CONCLUSIONS

Radiochemotherapy, including > or = 6 cycles of adjuvant temozolomide, was safe and prolonged survival of glioblastoma patients aged > or = 60 years. Aggressive therapy should not be withheld from patients aged > or = 60 years with good performance status because of age.

Target identification for stereotactic thalamotomy using diffusion tractography

BACKGROUND

Stereotactic targets for thalamotomy are usually derived from population-based coordinates. Individual anatomy is used only to scale the coordinates based on the location of some internal guide points. While on conventional MR imaging the thalamic nuclei are indistinguishable, recently it has become possible to identify individual thalamic nuclei using different connectivity profiles, as defined by MR diffusion tractography.

METHODOLOGY AND PRINCIPAL FINDINGS

Here we investigated the inter-individual variation of the location of target nuclei for thalamotomy: the putative ventralis oralis posterior (Vop) and the ventral intermedius (Vim) nucleus as defined by probabilistic tractography. We showed that the mean inter-individual distance of the peak Vop location is 7.33 mm and 7.42 mm for Vim. The mean overlap between individual Vop nuclei was 40.2% and it was 31.8% for Vim nuclei. As a proof of concept, we also present a patient who underwent Vop thalamotomy for untreatable tremor caused by traumatic brain injury and another patient who underwent Vim thalamotomy for essential tremor. The probabilistic tractography indicated that the successful tremor control was achieved with lesions in the Vop and Vim respectively.

CONCLUSIONS

Our data call attention to the need for a better appreciation of the individual anatomy when planning stereotactic functional neurosurgery.

[Vascular compression syndromes of the cranial nerves]

The blood vessels which are running nearby the cranial nerves and the brainstem can be elongated; curves and loops of the vessels may develop mostly due to the degenerative alterations of ageing and these vessels can compress the surrounding neural elements. The authors report a review of vascular compression syndromes based on the literature and their own experience. The typical clinical symptoms of the syndromes subserving the proper diagnosis, the pathomechanism, the significance of imaging especially the magnetic resonance angiography, the experience with the surgical technique of microvascular decompression which is the only causal treatment of the syndromes are discussed. In cases of non-responsible medical treatment the microvascular decompression should be the eligible treatment in certain syndromes (trigeminal and glossopharyngeal neuralgia, hemifacial spasm) for it is a highly effective and low risk method.

[Anterior cervical fusion on the lower cervical spine: own clinical experience]

Both acute and chronic instability of the cervical spine can be succesfully treated by anterior crevical fusion. The main goal is to create a spondylodesis through which the instable motion segments are fixed in the position defined by the surgeon. The spondylodesis is realised by the bone healing of the intervertebral space. The consolidation itself is facilitated by the operative stabilisation of the segments involved, and also by the implantation/transplantation of the osteoproductive/osteoinductive materials. The sooner consolidation is achieved, the more likely it is to be able to avoid the material dependent complications and/or that of dislocation. So as to support this theory a retrospective clinical/radiological study was performed. During this the length and the safety of the consolidation was measured by applying various anterior cervical plating systems. A total of 485 patients having cervical injuries or degenerative disc disease were treated by anterior cervical plating. For bone transplantation partly pure autolog spongious partly autolog cortico-spongious morsalised bone chips, furthermore autolog tricortical bone block were applied. A standard protocoll was used for data collection, evaluation and also follow-up. The patients treated with plate systems were divided into 3 groups: Group 1: Non-locked H-plate system with autogeneous cancellous bone (155 trauma patients, for a total of 210 cervical motion segments, 1.35 segments/patients). Group 2: Non-locked H-plate system with tricortical autograft (167 patients, for a total of 290 cervical motion segments, 1.73 segments/patients). Group 3: Locked cervical plate system with tricortical autograft (73 patients, for a total of 110 cervical motion segments, 1.5 segments/patients). Patients treated with standalone cage belong to group 4. These cages were filled with autogenous cortico-spongiosus bone chips (90 patients, for a total of 90 cervical motion segments, 1.0 segments/patients). Evaluations included postoperative clinical, X-ray and CT examination, and follow-ups at 6, 16, 52, and 104 weeks. We established three grades, and classified the degree of bony fusion between the graft and vertebra: not-yet-fused, fused or non-union. When evaluating the results the following statements/observations were made: a) There is a fast and safe consolidation in the case of those patients that underwent dinamic disc osteosynthesis (p = 0.00001). b) Whereas performing fixation with non-locked or locked screw plate systems and strutgrafted with tricortical autograft created prolonged healing requiring months and developed non-unions more often (non-locked screw-plate system versus locked screw-plate system) (p > 0.05). c) Using locked screw-plate fixation systems non-union rate in our study was 21%, suggesting that this form of fixation has only a limited use. d) In our study complete consolidation without pseudoarthrosis was achieved by using standalone cages filled with autolog cortico-spongiosus bone chips, but bony healing was delayed due to cage coating and the substitution of pure autogenous spongiosa for cortico-spongiosus bone chips. It is recommended to treat acute/chronic instability of the cervical spine both by using non-fixed plate system with autolog cancellosus bone and by standalone cage filled with cortico-spongiosus bone chips as well. It is worth keeping in mind that by applying this lattest an extra surgery to harvest the graft will be avoided.

Regulation of cortical microcircuits by unitary GABA-mediated volume transmission

Gamma-aminobutyric acid (GABA) is predominantly released by local interneurons in the cerebral cortex to particular subcellular domains of the target cells1,2. This suggests that compartmentalized, synapse specific action of GABA is required in cortical networks for phasic inhibition2–4. However, GABA released at the synaptic cleft diffuses to receptors outside the postsynaptic density and thus tonically activates extrasynaptic GABAA and GABAB receptors, which include subtypes of both receptor families especially sensitive to low concentrations of GABA3–7. The synaptic and extrasynaptic action of GABA is in line with idea that neurons of the brain use synaptic (or wiring) transmission and nonsynaptic (or volume) transmission for communication8,9. However, reuptake mechanisms restrict the spatial extent of extrasynaptic GABAergic effects10,11 and it was proposed that concerted action of several presynaptic interneurons or sustained firing of individual cells or increased release site density is required to reach ambient GABA levels sufficient to activate extrasynaptic receptors4,9,11–13. Here we show that individual neurogliaform cells release GABA sufficient for volume transmission within the axonal cloud and thus neurogliaform cells do not require synapses to produce inhibitory responses in the overwhelming majority of nearby neurons. Neurogliaform cells suppress connections between other neurons acting on presynaptic terminals which do not receive synapses at all in the cerebral cortex and, moreover, reach extrasynaptic, δ subunit containing GABAA (GABAA_δ) receptors responsible for tonic inhibition. We reveal that GABAA_δ receptors are localized to neurogliaform cells preferentially among cortical interneurons. Neurosteroids, which are modulators of GABAA_δ receptors, alter unitary GABAergic effects between neurogliaform cells. In contrast to the specifically placed synapses formed by other interneurons, the output of neurosteroid sensitive neurogliaform cells represents the ultimate form of spatial unspecificity in GABAergic systems leading to long lasting network hyperpolarization combined with widespread suppression of communication in the local circuit.

[Factors affecting the development of chronic hydrocephalus following subarachnoid hemorrhage, with special emphasis on the role of ventricular and lumbar drainage]

Hydrocephalus is a common complication of aneurysmal subarachnoid hemorrhage. Numerous studies have dealt so far with the triggering cause of the chronic cerebrospinal fluid (CSF) absorptional and circulatory disorders. Despite the fact that these studies gave several different explanations, most of them agreed on the fact that the obstruction of CSF pathway has a crucial role in the development of the clinical feature. By examining three years' clinical cases, the authors were trying to find out which are the factors that influence the development of the late hydrocephalus which follows the subarachnoid hemorrhage; moreover to find out if the incidence of the latter may be decreased by a continuous drainage of CSF which advances its purification. One hundred and seventy-one patients (one hundred and twenty-seven females) were treated by aneurysmal SAH at Department of Neurosurgery, University of Szeged between 2002 and 2005. The following parameters were recorded: gender, clinical state, risk factors (smoking, consuming alcohol and hypertension), the method and the time of surgical treatment as well as CSF drainage. The studies have shown that the risk of incidence of chronic hydrocephalus were higher in men and in case of severe clinical state with severe SAH. The disturbed CSF circulation and/or absorption were positively correlated with consuming alcohol and hypertension, while smoking did not affect it. The rate of the incidence of chronic hydrocephalus among our patients was lower (5.8%) compared to the results of other studies (7-40%) suggests that disturbance of CSF circulation and/or absorption may be avoided in the majority of cases by continuous external ventricular or lumbar CSF drainage, which is applied routinly.

[Non-obstructive hydrocephalus internus with a rare pathogenesis--mucormycosis]

The case of a 9-year-old boy is presented in this article who developed a rare fungal infection of central nervous system. The histopathologic examination has revealed mucormycosis. The diagnosis wasn't confirmed microbiologically as the culture and PCR were negativ. After the iv administered Amphotericin B lipid complex the MR images of the brain have improved. The mucormycosis classically develops in immunodeficient patients and presents an acute, fulminant, mostly lethal infection. This case is very unusual, because the chronic, isolated CNS mucormycosis has slowly developed in immuncompetent patient and only one symptom was the long existing headache. The aim of this paper is reporting the case history and to find out the possible way of infection.

[Successful surgical removal of a mesencephalic cavernous angioma, which was responsible for progressive neurological deficits]

Cavernous angiomas comprise 5-10% of all vascular malformations in the central nervous system, occurring most frequently in the supratentorial region, and 20% of them in the brain stem. According to literature, brain stem cavernous angiomas occur most frequently in the pons (60%), and equally in the mesencephalon (20%) and in medulla oblongata. In clinical evaluation the authors describe the successful removal of a mesencephalic cavernous angioma causing progressive neurological deficits and symptoms. The authors present a case of a 51 year old female, who had developed 1 year prior to her admittance: fatigue, weakness in the right upper limb and fingers, right lower limb ataxia. One month later, her lower right limb developed sensory deficits. The first neurological exploration indicated dysarthria, moderate facial and right hemiparesis, hemihypaesthesia and ataxia. CT and MR imaging indicated multilobulated cavernomas in the mesencephalon. After conservative treatment the patient became almost symptom free, and thus neurosurgical treatment was not discussed. Later on her symptoms fluctuated, but after 6 month she suddenly developed progressive right hemiparesis, right facial weakness, serious dysphasia, and emotional incontinence combined with continuous spastic sobbings. The control MRI showed enlargement of the cavernomas and new extravasation. Surgery was indicated for removing the cavernomas. The left infratentorial, supracerebellar approach revealed a blood engorged cavernoma in the center of the mesencephalon, almost dividing it. The cavernomas and accompanying haematoma was extirpated. The patient's neurological symptoms rapidly improved after surgery, her dysphasia as well as motor weakness have disappeared. Six days after surgery, we discharged a neurologically symptomless and self-supporting patient. The literature and the presented case indicates that the correct timing and proper surgery allows brain stem cavernomas to be safely removed, or significantly bated, which results in the massive regression of neurological symptoms.

Output of neurogliaform cells to various neuron types in the human and rat cerebral cortex

Neurogliaform cells in the rat elicit combined GABAA and GABAB receptor-mediated postsynaptic responses on cortical pyramidal cells and establish electrical synapses with various interneuron types. However, the involvement of GABAB receptors in postsynaptic effects of neurogliaform cells on other GABAergic interneurons is not clear. We measured the postsynaptic effects of neurogliaform cells in vitro applying simultaneous whole-cell recordings in human and rat cortex. Single action potentials of human neurogliaform cells evoked unitary IPSPs composed of GABAA and GABAB receptor-mediated components in various types of inteneuron and in pyramidal cells. Slow IPSPs were combined with homologous and heterologous electrical coupling between neurogliaform cells and several human interneuron types. In the rat, single action potentials in neurogliaform cells elicited GABAB receptor-mediated component in responses of neurogliaform, regular spiking, and fast spiking interneurons following the GABAA receptor-mediated component in postsynaptic responses. In conclusion, human and rat neurogliaform cells elicit slow IPSPs and reach GABAA and GABAB receptors on several interneuron types with a connection-specific involvement of GABAB receptors. The electrical synapses recorded between human neurogliaform cells and various interneuron types represent the first electrical synapses recorded in the human cortex.

Kinetics of the cellular immune response following closed head injury

BACKGROUND

The contribution of brain edema to brain swelling in cases of traumatic brain injury (TBI) remains a critical problem. We believe that inflammatory reactions may play a fundamental role in brain swelling following a head injury. Although possible roles of microglia activation and the release of mediators have been suggested, direct evidence of cellular immune reactivity in diffuse brain injury following closed head trauma is lacking. Accordingly, the objective of this study was to assess the temporal pattern of microglia activation and lymphocyte migration in an experimental model of TBI.

METHOD

An impact acceleration TBI model was utilized to induce diffuse brain damage in adult Wistar rats. The animals were separated into three groups: unoperated controls, sham-operated controls and trauma group. At various times after TBI induction (5 min-24 h), rats were perfused transcardially. Sagittal brain sections were analyzed with immunohistochemical markers of CD3 to reveal the presence of T-lymphocytes, and by immunochemistry for the detection of CD11b to reveal microglia activation within the brain parenchyma.

FINDINGS

In the control groups, scattered T-cells were found in the brain parenchyma. In the trauma group, TBI induced microglia activation and a transient biphasic T-cell infiltration of the brain parenchyma in all regions was found, beginning as early as 30 min post injury and reaching its maximum values at 45 min and 3 h after trauma induction.

CONCLUSION

These results lead us to suggest that the acute response to severe head trauma with early edema formation is likely to be associated with inflammatory events which might be triggered by activated microglia and infiltrating lymphocytes. It is difficult to overestimate the clinical significance of these observations, as the early and targeted treatment of patients with severe head injuries with immunosuppressive medication may result in a far more favorable outcome.

[Amnesic syndrome following lesion of the fornix or does reversible Korsakow's syndrome exist?]

The 53-year-old female patient had suffered massive subarachnoid bleeding due to rupture of left-localized aneurysm of the anterior communicant artery. Following the neurosurgical intervention, deterioration of consciousness related to strong vasospasm occurred. Cerebral CT examination was performed, showing a 0.5 cm ischaemic lesion of the left hippocampal fornix. Due to intensive therapy, the patient recovered gradually, however considerable short-time memory deficit and severe anterograde amnesia remained. Admission of the patient in psychiatric care 5 weeks after the operation was necessary since acute deterioration had been added to memory disturbance and anterograde amnesia. Clinical features included severe short-time memory deficit, continuous and severe anterograde amnesia, disorientation, alterations of verbal fluency and abstraction. The amnesic syndrome was probably related to the hippocampal damage, but considering the development of cognitive deficits, cerebral CT was performed again, which verified internal hydrocephalus. A ventriculo-peritoneal shunt has been implanted and the patient was re-admitted in psychiatry care because of her memory deficit, anterograde amnesia and disorientation. Thereafter, low doses of citalopram and donepezil therapy was started together with temporarily used antipsychotic medication (risperidone). Gradual, but continuous improvement of memory and cognitive function could be detected, with total recovery after one year. The deficits in long- and short-term memory, orientation and cognition were totally restored.

Excitatory effect of GABAergic axo-axonic cells in cortical microcircuits

Axons in the cerebral cortex receive synaptic input at the axon initial segment almost exclusively from gamma-aminobutyric acid-releasing (GABAergic) axo-axonic cells (AACs). The axon has the lowest threshold for action potential generation in neurons; thus, AACs are considered to be strategically placed inhibitory neurons controlling neuronal output. However, we found that AACs can depolarize pyramidal cells and can initiate stereotyped series of synaptic events in rat and human cortical networks because of a depolarized reversal potential for axonal relative to perisomatic GABAergic inputs. Excitation and signal propagation initiated by AACs is supported by the absence of the potassium chloride cotransporter 2 in the axon.

[The role of MR angiography in predicting operative results of microvascular decompression in patients with trigeminal neuralgia]

INTRODUCTION AND OBJECTIVES

The results of medium-term outcome of microvascular decompression (MVD) for trigeminal neuralgia are presented. The authors compare the preoperative 3-dimension magnetic resonance angiography (MRA) results with the surgical findings during MVD. Information, provided by MRA, are evaluated regarding to the prognostic significance in typical TN, atypical TN and persistent idiopathic facial pain (PIFP). The significance of clinical symptoms and the type of neurovascular compression (NC) are investigated in respect of the postoperative success and recurrent symptoms.

METHODS AND RESULTS

MRA was performed in 310 consecutive patients with TN and PIFP. The MRA image was positive in 179 (58%) of the 310 cases. 68.2% of the typical TN group, 49.2% of the atypical TN group and 3.2% of the PIFP group were positive. MVD was performed in 116 of the MRA positive cases. Four years following the MVD, 69% of the patients gave an excellent and 23% a good result. The surgical findings corresponded with the MRA images. NC could be ruled out in the background of PIFP. The rate of recurrent symptoms following MVD is 21% in the typical TN group while it is 41% in the atypical TN group. The pure venous compression showed 57% pain-recurrence rate following MVD.

CONCLUSIONS

The clinical symptoms and preoperative MRA carry considerable information, which can predict the outcome of the MVD and the rate of recurrent symptoms. Atypical TN and venous compression are bad prognostic factors.

[Increasing cerebral perfusion pressure in serious cranial injury--contradictory effects of dopamine]

BACKGROUND

Management of cerebral perfusion pressure is an important element of the treatment of traumatic brain injury. Vasopressors are accepted as a method of choice to increase mean arterial blood pressure and thus cerebral perfusion pressure in the face of rising intracranial pressure. There are, however, some unresolved issues and potential risks to this therapy.

MATERIAL AND METHODS

This study therefore examines the effects of dopamine on physiological changes as well as on brain edema and water content that can be readily assessed by MRI/MRS in (1) a rodent model of rapidly rising intracranial pressure, caused by diffuse injury with secondary insult and (2) a model of cortical contusion.

RESULTS

Dopamine was capable of restoring cerebral perfusion pressure in the model of rapidly rising intracranial pressure. However, this was associated with only a partial restoration of cerebral blood flow. In the brain tissue two profiles of change in the apparent diffusion coefficient of water (ADCw) were seen; one in which ADCw recovered to baseline, and one in which ADCw remained persistently low. Despite that dopamine did not alter these profiles, MRI-assessed tissue water content was increased four hours after injury and dopamine increased cerebral water content in both subgroups of injury, especially in the subgroup with a persistently low ADCw (p < 0.01). In the contusion group dopamine significantly worsened the edema both in the injured and in the contralateral area of hippocampus and temporal cortex even though the ADCw values did not change, except for the contralateral hippocampus, where both water content and ADC, values rose with treatment, suggesting extracellular accumulation of water.

CONCLUSION

The results suggest that dopamine has a double effect--while it temporarily and partially restores cerebral blood perfusion, at the same time it induces an increase in brain swelling and thus an increase in intracranial pressure in some cases. It is possible that in a subgroup of patients vasopressor treatment leads to an opposite effect several hours later. Vasopressor therapy in the clinical setting therefore should be cautiously applied.

[Preliminary experience with controlled lumbar drainage in medically refractory intracranial hypertension]

INTRODUCTION

The contribution of brain edema to brain swelling in cases of traumatic brain injury remains a critical problem. In head injury, the swelling and eventual rise in intracranial pressure is a frequent cause of death, and in survivors the poor prognosis with sustained elevation of ICP has been well documented.

OBJECTIVE

The objective this study was to evaluate the effect of controlled lumbar cerebrospinal fluid drainage in adult patients with refractory intracranial hypertension following severe brain injury.

METHOD

The study involved 10 head injured patients (GCS < or = 8) with medically refractory intracranial hypertension. Aggressive treatment included the repeated steps of the Brain Trauma Foundation's guidelines, barbiturate coma and in many cases decompressive craniectomy as well. After institution of a lumbar drain, cerebrospinal fluid drainage was maintained under control of intracranial pressure (ICP) and neurological status. ICP and cerebral perfusion pressure before and after initiation of lumbar cerebrospinal fluid drainage and related complications were documented.

RESULTS

All patients demonstrated an immediate decrease of ICP (from 30.6 +/- 4.7 mm Hg to 11.5 +/- 3.9 mm Hg, mean +/- SD) and a concomitant increase of cerebral perfusion pressure. In seven patients the decrease of ICP was long lasting and 5 of them had a favourable outcome. Two patients survived with a severe permanent neurologic deficit and only three patients died because of the progressive brain edema, which developed despite of the maximum therapy.

CONCLUSION

In conclusion we may consider, that controlled lumbar cerebrospinal fluid drainage is a potentially useful treatment in cases of severe traumatic brain injury when maximal medical therapy and ventricular cerebrospinal fluid evacuation have failed to control high intracranial hypertension. The danger of herniation is minimized by considering lumbar drainage in the presence of discernible basilar cisterns only.

Favorable Early Outcome of Carotid Artery Stenting Without Protection Devices

Background and Purpose— Protection devices are increasingly used in carotid artery stenting. However, no randomized trial has been conducted to evaluate the efficacy of such devices, and arguments have also been formulated against their routine use. We set out to investigate the complication rates associated with carotid artery stenting performed without protection devices. Applicability of covered stents in the carotid system was also evaluated.

Methods— Between January 2001 and July 2003, 245 consecutive patients (260 hemispheres) underwent carotid artery stenting. No protection devices were applied. Covered stents were implanted in 31 (12.1%) cases. The incidence of complications during the intervention and the subsequent 30-day follow-up period was recorded.

Results— The technical success rate was 98.8%. One postprocedural nonneurological death (0.4%) occurred. Neurological complications (inclusive of transient ischemic attacks) were observed in 14 cases (5.4%). The rate of major complications (death, major stroke, and myocardial infarction) was 1.6% among the symptomatic and 1.5% among the asymptomatic cases. The rate of minor strokes was 3.2% in the symptomatic and 1.5% in the asymptomatic group. Of the neurological complications, 64.3% occurred postprocedurally. No ipsilateral neurological complications were detected in the subgroup treated with covered stents.

Conclusions— Carotid artery stenting without protection devices appears to be safe. Most of the neurological complications could not have been prevented with protection devices, because they occurred after the intervention. The application of covered stents may reduce the rate of embolization-related complications in the periprocedural period.