Richard P. Greenberg

Traumatic Acute Subdural Hematoma — Major Mortality Reduction in Comatose Patients Treated within Four Hours

To discover which factors contributed to recovery after surgical intracranial decompression, we reviewed the records of 82 consecutive comatose patients with traumatic acute subdural hematoma (ASDH) who were treated in a single center under a uniform protocol. The delay from injury to operation was the factor of greatest therapeutic importance. Patients who underwent surgery within the first four hours had a 30 per cent mortality rate, as compared with 90 percent in those who had surgery after four hours (P less than 0.0001). Other important prognostic variables included results of the initial neurologic examination, sex, multimodality-evoked potentials, and postoperative intracranial pressure (ICP). If all patients with traumatic ASDH were taken directly to hospitals equipped to diagnose and remove the hematoma within four hours of injury, mortality rates could be reduced considerably.

Improved confidence of outcome prediction in severe head injury A comparative analysis of the clinical examination, multimodality evoked potentials, CT scanning, and intracranial pressure

An analysis of clinical signs, singly or in combination, multimodality evoked potentials (MEPs), computerized tomography scans, and intracranial pressure (ICP) data was undertaken prospectively in 133 severely head-injured patients to ascertain the accuracy, reliability, and relative value of these indicants individually, or in various combinations, in predicting one of two categories of outcome. Erroneous predictions, either falsely optimistic (FO) or falsely pessimistic (FP), were analyzed to gain pathophysiological insights into the disease process. Falsely optimistic predictions occurred because of unpredictable complications, whereas FP predictions were due to intrinsic weakness of the indicants as prognosticators. A combination of clinical data, including age, Glasgow Coma Scale (GCS) score, pupillary response, presence of surgical mass lesions, extraocular motility, and motor posturing predicted outcome with 82% accuracy, 43% with over 90% confidence. Nine percent of predictions were FO and 9% FP. The GCS score alone was accurate in 80% of predictions, but at a lower level of confidence (25% at the over-90% level), with 7% FO and 13% FP. Computerized tomography and ICP data in isolation proved to be poor prognostic indicants. When combined individually with clinical data, however, they increased the number of predictions made with over 90% confidence to 52% and 55%, respectively. Data from MEPs represented the most accurate single prognostic indicant, with 91% correct predictions, 25% at the over-90% confidence level. There were no FP errors associated with this indicant. Supplementation of the clinical examination with MEP data yielded optimal prognostic power, an 89% accuracy rate, with 64% over the 90% confidence level and only 4% FP errors. The clinical examination remains the strongest basis for prognosticating outcome in severe head injury, but additional studies enhance the reliability of such predictions.

Effects of therapeutic pentobarbital coma on multimodality evoked potentials recorded from severely head-injured patients.

We sought to determine whether pentobarbital (PB) coma compromises the use of evoked potentials (EPs) in the assessment of brain dysfunction and of the prognosis of severely head-injured patients. Therefore, the effects of therapeutic PB on somatosensory (SEPs, BSEPs), visual (VEPs), and auditory (BAEPs) evoked potentials recorded from 20 patients early after injury were analyzed. Seventeen head-injured patients served as controls. EP studies were obtained shortly after admission (Mean Day 2, PB present) and approximately 2 weeks after injury (Mean Day 15, PB absent). The mean serum level of PB in the treatment group was 1.9 mg/100 ml. The drug effect was assessed by comparisons between the PB and the control groups. Statistical analyses were based on differences observed between two studies in the same patient. Analyses of covariance (F tests) were performed on data from all modalities. Wave form complexity was minimally affected by the drug. Middle and long latency components of the SEP were depressed by PB, and latencies of BSEP peaks and the early components of the SEP were delayed. The amplitude of some VEP peaks was reduced by PB. The BAEP was not significantly altered. All of the observed effects of PB were determined to be due to the hypothermia exhibited by PB-treated patients (mean temperature, 36.1 degrees C), which was not seen in the control group (mean, 37.8 degrees C). It is concluded that, with appropriate interpretation, EPs can be used to monitor brain function in head-injured patients when PB therapy is used.

Evoked potentials in severe head injury.

Provided herein is a summary of findings by the authors and other investigators regarding the application of evoked potential studies to the assessment of neurologic function in severely head-injured patients in the acute and subacute stages postinjury. Multimodality Evoked Potentials (MEPs) are reportedly useful in three primary areas: 1) diagnosis; 2) prognosis; and 3) monitoring recovery. In diagnosis, the abnormalities in MEPs can be associated specifically with focal sensory/motor deficits such as hemiparesis and, generally, with the severity and extent of brain dysfunction. MEP abnormalities that are severe reflect irreversible damage while the mild abnormalities point to transient, reversible CNS dysfunction. Definition of the severity and extent of brain dysfunction by MEPs allows an accurate prediction of outcome, or the potential for recovery. Their accuracy is superior to many commonly used indices and MEP results add strength to clinical indicators of prognosis. Changes in MEP results obtained within a patient over time can be used to trace recovery and assess, for an individual, the functional consequences of secondary neurologic insult or medical complication. The authors conclude that MEP studies may serve a useful function as noninvasive indices of neurologic function in the management of severely head-injured patients.

Early Prognosis After Severe Human Head Injury Utilizing Multimodality Evoked Potentials

Diagnostic studies used to evaluate comatose patients often yield information concerning the anatomical condition, i.e.,presence or absence of haematomas, brain displacements etc., not the functional condition of the brain and related structures. For example, a normal cerebral angiogram of computerized axial tomogram may be obtained in patients who succumb to their disease or survive with neurological deficits never detected by these studies. Evoked potentials, on the other hand, like the patients’ neurological examination, depend upon neuronal vitality for their realization, and are, therefore, in important method of assessing the functional state of the brain irrespective of the presence or absence of anatomical alterations.

Pathophysiology and Clinical Significance of ICP Course in Comatose, Patients with Severe Head Injury

Intracranial pressure (ICP) levels in comatose, severe head injury patients can vary considerably during the initial 7–10 days after trauma (Miller et al. 1977). Intracranial hemorrhage and hydrocephalus are among the entities known to drive the ICP up but they can often be successfully treated (Galbraith and Teasdale 1981). However, posttraumatic brain edema, a frequent cause of intracranial hypertension, is sometimes difficult to control and may result in brain death (Bruce et al. 1981). In a consecutive series of patients with severe head injury vigorously treated by a standard protocol that included emergency evacuation of mass lesions and intensive care (Becker et al. 1977) we identified four ICP courses that were associated with different patient outcome categories. To gain insight into the pathophysiological substrate that contributes to these ICP courses and the significance of ICP levels to brain function following severe head trauma we analysed the interaction of cortical and brain stem evoked potentials (EP), CT scan, neurological examination, autopsy and operative findings, admission blood pressure, arterial blood gases, secondary systemic and CNS complications and patient outcome in each of the four ICP courses identified.

The Hollow Screw Technique for Monitoring Intracranial Pressure

In 1972 the authors developed a system for monitoring intracranial pressure (ICP) from the subarachnoid space over the cerebral hemispheres (1). The system is based on a specially designed hollow screw. The screw is threaded into the skull through a 5 mm twist drill hole after opening the dura and arachnoid with a small currette. The screw is connected to a strain gauge transducer by means of saline filled tubing to record ICP. The system is calibrated by opening the bedside transducer to air through a bacteriologic filter. The screw insertion is performed in the neurosurgical ward under local anesthesia.