Intracranial Pressure :: physiology
Department of Neurology, Chongqing Medical University, Chongqing, China.
OBJECTIVES To investigate the feasibility of Electroencephalogram (EEG) power spectrum analysis as a noninvasive method for monitoring intracranial pressure (ICP). METHODS The EEG signals were recorded in 62 patients (70 cases) with central nervous system (CNS) disorders in our hospital. By using self-designed software, EEG power spectrum analysis was conducted and pressure index (PI) was calculated automatically. Intracranial pressure was measured by lumbar puncture (LP). RESULTS We found a significant negative correlation between PI and ICP (r =-0.849, p < 0.01). CONCLUSIONS The PI obtained from EEG analysis is correlated with ICP. Analysis of specific parameters from EEG power spectrum might reflect the ICP.
Most cited papers:
BACKGROUND and PURPOSE: Animal research and clinical studies in head trauma patients suggest that moderate hypothermia may improve outcome by attenuating the deleterious metabolic processes in neuronal injury. Clinical studies on moderate hypothermia in the treatment of acute ischemic stroke patients are still lacking. METHODS: Moderate hypothermia was induced in 25 patients with severe ischemic stroke in the middle cerebral artery (MCA) territory for therapy of postischemic brain edema. Hypothermia was induced within 14+/-7 hours after stroke onset and achieved by external cooling with cooling blankets, cold infusions, and cold washing. Patients were kept at 33 degreesC body-core temperature for 48 to 72 hours, and intracranial pressure (ICP), cerebral perfusion pressure, and brain temperature were monitored continuously. Outcome at 4 weeks and 3 months after the stroke was analyzed with the Scandinavian Stroke Scale (SSS) and Barthel index. The side effects of induced moderate hypothermia were analyzed. RESULTS: Fourteen patients survived the hemispheric stroke (56%). Neurological outcome according to the SSS score was 29 (range, 25 to 37) 4 weeks after stroke and 38 (range 28 to 48) 3 months after stroke. During hypothermia, elevated ICP values could be significantly reduced. Herniation caused by a secondary rise in ICP after rewarming was the cause of death in all remaining patients. The most frequent complication of moderate hypothermia was pneumonia in 10 of the 25 patients (40%). Other severe side effects of hypothermia could not be detected. CONCLUSIONS: Moderate hypothermia in the treatment of severe cerebral ischemia is not associated with severe side effects. Moderate hypothermia can help to control critically elevated ICP values in severe space-occupying edema after MCA stroke and may improve clinical outcome in these patients.
Department of Emergency Medicine, University of Cincinnati, Ohio 45267-0769, USA. Rashmikant.Kothari@uc.edu
BACKGROUND AND PURPOSE: Hemorrhage volume is a powerful predictor of 30-day mortality after spontaneous intracerebral hemorrhage (ICH). We compared a bedside method of measuring CT ICH volume with measurements made by computer-assisted planimetric image analysis. METHODS: The formula ABC/2 was used, where A is the greatest hemorrhage diameter by CT, B is the diameter 90 degrees to A, and C is the approximate number of CT slices with hemorrhage multiplied by the slice thickness. RESULTS: The ICH volumes for 118 patients were evaluated in a mean of 38 seconds and correlated with planimetric measurements (R2 = 9.6). Interrater and intrarater reliability were excellent, with an intraclass correlation of .99 for both. CONCLUSIONS: We conclude that ICH volume can be accurately estimated in less than 1 minute with the simple formula ABC/2.
Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota 55905, USA.
Spinal cerebrospinal fluid (CSF) leaks are often implicated as the cause of the syndrome of spontaneous intracranial hypotension, but they have rarely been demonstrated radiographically or surgically. The authors reviewed their experience with documented cases of spinal CSF leaks of spontaneous onset in 11 patients including their surgical observations in four of the patients. The mean age of the six women and five men included in the study was 38 years (range 22-51 years). All patients presented with a postural headache; however, most had additional symptoms, including nausea, emesis, sixth cranial-nerve paresis, or local back pain at the level of the CSF leak. All patients underwent indium-111 radionucleotide cisternography or computerized tomographic (CT) myelography. The location of the spontaneous CSF leak was in the cervical spine in two patients, the cervicothoracic junction in three patients, the thoracic spine in five patients, and the lumbar spine in one patient. The false negative rate for radionucleotide cisternography was high (30%). Subdural fluid collections, meningeal enhancement, and downward displacement of the cerebellum, resembling a Chiari I malformation, were commonly found on cranial imaging studies. In most patients, the symptoms resolved in response to supportive measures or an epidural blood patch. Leaking meningeal diverticula were found to be the cause of the CSF leak in four patients who underwent surgery. In three patients these diverticula could be ligated with good result but in one patient an extensive complex of meningeal diverticula was found to be inoperable. Two patients had an unusual body habitus and joint hypermobility, and two other patients had suffered a spontaneous retinal detachment at a young age. In conclusion, spontaneous spinal CSF leaks are uncommon, but they are increasingly recognized as a cause of spontaneous intracranial hypotension. Most spinal CSF leaks are located at the cervicothoracic junction or in the thoracic spine, and they may be associated with meningeal diverticula. The radiographic study of choice is CT myelography. The disease is usually self-limiting, but in selected cases our experience with surgical ligation of leaking meningeal diverticula has been satisfactory. An underlying connective tissue disorder may be present in some patients with a spontaneous spinal CSF leak.
Decompressive bifrontal craniectomy in the treatment of severe refractory posttraumatic cerebral edema.
Department of Neurosurgery, University of Virginia Health Sciences Center, Charlottesville, USA.
OBJECTIVE: The management of malignant posttraumatic cerebral edema remains a frustrating endeavor for the neurosurgeon and the intensivist. Mortality and morbidity rates remain high despite refinements in medical and pharmacological means of controlling elevated intracranial pressure; therefore, a comparison of medical management versus decompressive craniectomy in the management of malignant posttraumatic cerebral edema was undertaken. METHODS: At the University of Virginia Health Sciences Center, 35 bifrontal decompressive craniectomies were performed on patients suffering from malignant posttraumatic cerebral edema. A control population was formed of patients whose data was accrued in the Traumatic Coma Data Bank. Patients who had undergone surgery were matched with one to four control patients based on sex, age, preoperative Glasgow Coma Scale scores, and maximum preoperative intracranial pressure (ICP). RESULTS: The overall rate of good recovery and moderate disability for the patients who underwent craniectomies was 37%(13 of 35 patients), whereas the mortality rate was 23%(8 of 35 patients). Pediatric patients had a higher rate of favorable outcome (44%, 8 of 18 patients) than did adult patients. Postoperative ICP was lower than preoperative ICP in patients who underwent decompression (P = 0.0003). Postoperative ICP was lower in patients who underwent surgery than late measurements of ICP in the matched control population. A statistically significant increased rate of favorable outcomes was seen in the patients who underwent surgery compared to the matched control patients (15.4%)(P = 0.014). All patients who exhibited sustained ICP values above 40 torr and those who underwent surgery more than 48 hours after the time of injury did poorly. Evaluation of the 20 patients who did not fit into either of those categories revealed a 60% rate of favorable outcome and a statistical advantage over control patients (P = 0.0001). CONCLUSION: Decompressive bifrontal craniectomy provides a statistical advantage over medical treatment of intractable posttraumatic cerebral hypertension and should be considered in the management of malignant posttraumatic cerebral swelling. If the operation can be accomplished before the ICP value exceeds 40 torr for a sustained period and within 48 hours of the time of injury, the potential to influence outcome is greatest.
The Westmead Head Injury Project outcome in severe head injury. A comparative analysis of pre-hospital, clinical and CT variables.
Department of Neurosurgery, Westmead Hospital, Sydney, Australia.
A prospective study of 315 consecutive patients with a severe head injury was undertaken to study factors contributing to mortality and morbidity, both in the pre-hospital and hospital phases. Entry criteria were a Glasgow Coma Scale (GCS) score of 8 or less after non-surgical resuscitation within 6 h of the injury, or a deterioration to that level within 48 h. Patients with gunshot wounds or who were dead on arrival were excluded. End points of the study were either death or at 6 months after the injury. Predictors of mortality were increasing age, the presence of hypotension, a low GCS, abnormal motor responses and pupillary non-reactivity. In the 167 patients in whom intracranial pressure (ICP) was measured, raised ICP and failure to respond to treatment for raised ICP also predicted mortality. Three CT predictors of mortality were the presence of cerebral oedema, intraventricular blood and the degree of midline shift. When analysed using logistic regression, the most accurate model (accuracy 84.4%) included increasing age, abnormal motor responses and the three CT indicators. Analysis of the data for 'good'(Glasgow Outcome Score (GOS) 1 and 2) vs 'poor'(GOS 3 and 4) survival at 6 months was also performed using logistic regression. The model which provided the most accurate prediction of poor outcome included age, hypotension and three different CT characteristics, subarachnoid blood, intracerebral haematoma or intracerebral contusion (accuracy 72.5%).
Continuous monitoring of partial pressure of brain tissue oxygen in patients with severe head injury.
Ischemia is one of the major factors causing secondary brain damage after severe head injury. We have investigated the value of continuous partial pressure of brain tissue oxygen (PbrO2) monitoring as a parameter for cerebral oxygenation in 22 patients with severe head injury (Glasgow Coma Scale score,< or = 8). Jugular bulb oxygenation, intracranial pressure, and cerebral perfusion pressure were simultaneously recorded. O2 and CO2 reactivity tests were performed daily to evaluate oxygen autoregulatory mechanisms. PbrO2 monitoring was started an average of 7.0 hours after trauma with a mean duration of 74.3 hours. No complications were seen, and the calibration of the catheters after measurement showed a zero drift of 1.2 +/- 0.8 mm Hg and a sensitivity drift of 9.7 +/- 5.3%. In 86% of patients, PbrO2 was < 20 mm Hg in the acute phase. Mean PbrO2 significantly increased during the first 24 hours after injury. Two distinct patterns of change of PbrO2 over time were noted. The first pattern was characterized by normal stable levels after 24 hours, and the second was characterized by transiently elevated levels of PbrO2 during the second and third days. PbrO2 values < or = 5 mm Hg within 24 hours after trauma negatively correlated with outcome. O2 reactivity was significantly lower in patients with good outcomes. CO2 reactivity showed no constant pattern of change over time and was not correlated with outcome. Increased hyperventilation was shown to decrease PbrO2 in some patients. Accurate detection of the moment of cerebral death was possible on the basis of the PbrO2 measurements. The correlation between PbrO2 and other parameters, such as intracranial pressure and cerebral perfusion pressure, was weak. We conclude that PbrO2 monitoring is a safe and clinically applicable method in patients with severe head injury. The early occurrence of ischemia after head injury can be monitored on a continuous basis. Deficiency of oxygen autoregulatory mechanisms can be demonstrated, and their occurrence is inversely related to outcome. For practical clinical use, the method seemed to be superior to jugular oximetry.
The effect of changes in cerebral perfusion pressure upon middle cerebral artery blood flow velocity and jugular bulb venous oxygen saturation after severe brain injury.
Department of Clinical Neurosciences, University of Edinburgh, Western General Hospital, Scotland.
Middle cerebral artery blood flow velocity and jugular bulb venous oxygen saturation (SJO2) were measured by transcranial Doppler (TCD) ultrasonography and continuous venous oximetry, respectively, in 41 severely brain-injured patients. The purpose of the study was to examine the relationships between TCD flow velocity, SJO2, and alterations in blood pressure (BP), intracranial pressure (ICP), and cerebral perfusion pressure (CPP). In these patients, CPP was reduced either by rising ICP or by falling BP. Both forms of reduction of CPP resulted in a greater fall in diastolic flow velocity than other flow parameters. As CPP decreased below a critical value of 70 mm Hg, a progressive increase in TCD pulsatility index (PI) was observed (r =-0.942, p less than 0.0001), accompanied by a fall in SJO2 (r = 0.78, p less than 0.0001). At pressures above 70 mm Hg, there was no correlation of either PI or SJO2 with CPP. The relationship between PI and CPP held true in patients with both focal and diffuse pathologies and was the same whether changes in CPP resulted from alterations in ICP or BP. The PI and SJO2 correlated better with CPP than with ICP or BP. Transcranial Doppler ultrasonography can identify states of reduced CPP. Decreases in SJO2 with falling CPP suggested progressive failure of cerebral blood flow to meet metabolic demands. Monitoring of TCD and SJO2 may be used to define the optimum CPP level for management of severely brain-injured patients.
Department of Surgery, New York Medical College, USA.
IAH causes multiple and profound physiologic abnormalities both within and outside the abdomen. IAP monitoring is easily performed by bladder measurements. Careful monitoring and prompt recognition and treatment of IAP are critical in patients after damage control surgery because IAH is extremely common in these patients. Use of mesh fascial prostheses at the initial celiotomy in high-risk patients may prevent the deleterious effects of IAH. IAH should be considered an earlier manifestation of ACS. Surgical intervention should be indicated by IAH and not delayed until ACS is clinically apparent.
Department of Neurosurgery, Asclepeion General Hospital, Athens, Greece.
OBJECTIVE Traumatic brain injury is associated with a stress response that includes hyperglycemia, which has been shown to worsen neurological outcome during cerebral ischemia and hypoxia. To better examine the relationship between hyperglycemia and outcome after head injury, we studied the clinical course of 267 head-injured patients who were admitted for treatment in the neurosurgical department of Asclepeion Hospital of Athens between January 1993 and November 1997. METHODS We prospectively studied 267 patients with moderate or severe craniocerebral injury (Glasgow Coma Scale scores, 3-12) who were treated surgically for evacuation of an intracranial hematoma and/or placement of a device for intracranial pressure monitoring under general anesthesia to determine the relationship between serum glucose levels, severity of injury, and neurological outcome. RESULTS Patients with severe head injury had significantly higher serum glucose levels than did those with moderate injury. Patients who subsequently had an unfavorable outcome had significantly higher glucose levels than did those with a better prognosis. Among the patients with more severe head injury, a glucose level greater than 200 mg/dl was associated with a worse outcome. In the same group of patients, a significant relationship was found between postoperative glucose levels, pupillary reaction, and maximum intracranial pressure during the first 24 hours. Multivariate analysis showed that postoperative glucose levels were an independent predictor of outcome. CONCLUSION Early hyperglycemia is a frequent component of the stress response to head injury, a significant indicator of its severity, and a reliable predictor of outcome.
Brain Trauma Foundation and Weill Medical College of Cornell University, New York, NY, USA.
The decrease in mortality and improved outcome for patients with severe traumatic brain injury over the past 25 years can be attributed to the approach of "squeezing oxygenated blood through a swollen brain". Quantification of cerebral perfusion by monitoring of intracranial pressure and treatment of cerebral hypoperfusion decrease secondary injury. Before the patient reaches hospital, an organised trauma system that allows rapid resuscitation and transport directly to an experienced trauma centre significantly lowers mortality and morbidity. Only the education of medical personnel and the institution of trauma hospital systems can achieve further improvements in outcome for patients with traumatic brain injuries.