Extracellular amino acid changes in patients during reversible cerebral ischaemia.

This study investigated the changes in extracellular chemistry during reversible human cerebral ischaemia. Delayed analysis was performed on samples taken from a subgroup of patients during aneurysm surgery previously reported. Frozen microdialysis samples from 14 patients who had all undergone temporary clipping of the ipsilateral internal carotid artery (ICA) were analysed for another 15 amino acids with HPLC and for glycerol with CMA-600.

Extracellular lactate/pyruvate and glutamate changes in patients during per-operative episodes of cerebral ischaemia.

Objective: Temporary Internal Carotid Artery (ICA) clipping necessary during aneurysm surgery was used as a model to investigate metabolic changes in the human brain during defined episodes of ischaemia.

Design: An observational study using intracerebral monitors: PBO2 (Neurotrend) and microdialysis (CMA, Sweden).

Subjects: 16 patients monitored during complex aneurysm surgery.

Clinical cerebral microdialysis--determining the true extracellular concentration.

Current monitoring of the cerebral extracellular chemistry of neurosurgical patients using microdialysis does not provide the true extracellular concentration because full equilibration across the membrane is not achieved. By varying the flow rate and extrapolating to zero flow, the relative recovery i.e.

Effects of variation in cerebral haemodynamics during aneurysm surgery on brain tissue oxygen and metabolism.

Objectives: This study explores the sensitivities of multiparameter tissue gas sensors and microdialysis to variations in blood pressure, CSF drainage and to well-defined periods of ischaemia accompanying aneurysm surgery, and their predictive value for infarction.

Methods: A Neurotrend sensor [brain tissue partial pressure of oxygen (PBO2), carbon dioxide (PBCO2), brain pH (pHB) and temperature] and microdialysis catheter were inserted into the appropriate vascular territory prior to craniotomy.

Results: Baseline data showed a clear correlation between PBO2 and mean arterial pressure (MAP) below a threshold of 80 mmHg.

Cerebral oxygen and microdialysis monitoring during aneurysm surgery: effects of blood pressure, cerebrospinal fluid drainage, and temporary clipping on infarction.

Object: The aim of this study was to investigate potential episodes of cerebral ischemia during surgery for large and complicated aneurysms, by examining the effects of arterial temporary clipping and the impact of confounding variables such as blood pressure and cerebrospinal fluid (CSF) drainage.

Methods: Brain tissue PO2, PCO2, and pH, as well as temperature and extracellular glucose, lactate, pyruvate, and glutamate were monitored in 46 patients by using multiparameter sensors and microdialysis. Baseline data showed that brain tissue PO2 decreased significantly, below a mean arterial pressure (MAP) threshold of 70 mm Hg.

Correlation between cerebral blood flow, substrate delivery, and metabolism in head injury: a combined microdialysis and triple oxygen positron emission tomography study.

Microdialysis continuously monitors the chemistry of a small focal volume of the cerebral extracellular space. Conversely, positron emission tomography (PET) establishes metabolism of the whole brain, but only for the duration of the scan. The objective of this study was to apply both techniques to head-injured patients simultaneously to assess the relation between microdialysis (glucose, lactate, lactate/pyruvate [L/P] ratio, and glutamate) and PET (cerebral blood flow [CBF], cerebral blood volume, oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen) parameters.

Adverse cerebral events detected after subarachnoid hemorrhage using brain oxygen and microdialysis probes.

Objective: A prospective observational study was conducted to investigate whether episodes of ischemia are detected by continuous cerebral monitoring and whether such episodes are related to clinical outcome.

Methods: Forty patients (35 after subarachnoid hemorrhage and 5 after complex aneurysm surgery) were monitored for a total of 174 days (mean, 4 d; range, 1-12 d). Brain tissue partial pressures of oxygen and carbon dioxide, pH, and temperature were measured continuously using Neurotrend sensors (Codman, Bracknell, England).

Multi-modal monitoring of acute brain injury.

Objective: To review the scientific basis for and utility of the traditional cerebral monitors used currently in neurointensive care, together with research techniques that are soon likely to become used in managing severe head injury and subarachnoid haemorrhage.

Design And Content: Firstly, the pathophysiology of acute brain injury including cerebral haemodynamics, oxygen and metabolism and the role of secondary insults are discussed. Secondly, the importance of assessment of cerebrovascular autoregulation and reactivity is reviewed together with methods for its continuous non-invasive measurement using transcranial Doppler and intracranial pressure/arterial pressure recordings.

Measurement of brain tissue oxygenation performed using positron emission tomography scanning to validate a novel monitoring method.

Object: The benefits of measuring cerebral oxygenation in patients with brain injury are well accepted; however, jugular bulb oximetry, which is currently the most popular monitoring technique used has several shortcomings. The goal of this study was to validate the use of a new multiparameter sensor that measures brain tissue oxygenation and metabolism (Neurotrend) by comparing it with positron emission tomography (PET) scanning.

Methods: A Neurotrend sensor was inserted into the frontal region of the brain in 19 patients admitted to the neurointensive care unit.

Clinical cerebral microdialysis: a methodological study.

Object: Clinical microdialysis enables monitoring of the cerebral extracellular chemistry of neurosurgical patients. Introduction of the technique into different hospitals' neurosurgical units has resulted in variations in the method of application. There are several variables to be considered, including length of the catheter membrane, type of perfusion fluid, flow rate of perfusion fluid, and on-line compared with delayed analysis of samples.

Malignant spinal neurofibrosarcoma.

Study Design: A report of a case of metastatic spinal neurofibrosarcoma.

Objective: To document metastatic neurofibrosarcoma as a cause of spinal cord compression and to review the literature.

Summary Of Background Data: Three previously reported cases of metastatic neurofibrosarcoma of the spine were reviewed.

Bilateral frontal extradural haematomas caused by rupture of the superior sagittal sinus: case report.

A 26-year-old male sustained simultaneous massive bilateral frontal extradural haematomas following a head injury as a result of a large tear of the superior sagittal sinus, without fracturing of the skull vault.

Spontaneous intralesional haemorrhage in dysembryoplastic neuroepithelial tumours: a series of five cases.

Five patients with dysembryoplastic neuroepithelial tumour (DNT) showing extensive secondary haemorrhage, a finding not previously associated with these neoplasms, are described. The clinical presentations, neuroimaging findings, and histopathological features of these patients are reviewed. One patient, a previously asymptomatic 12 year old girl, presented with an acute intracerebral haemorrhage into a DNT.

Sprouting of peripherally regenerating primary sensory neurones in the adult central nervous system.

We have studied the ability of primary afferent neurones to proliferate within the grey matter of the dorsal horn following the degeneration of other, nearby, afferent fibres. The peripheral branches of primary afferents have the capacity to regenerate successfully over long distances, and we have examined the possibility that when they are so doing, the neurones' status changes to facilitate greatly the sprouting of afferent fibres within the dorsal horn. "Spared root" preparations (rhizotomies of L3, L4, L6, S1, and the caudal half of L5, sparing the rostral half of the L5 dorsal root) were made in adult rats.