Relation between intracranial pressure, computed tomographic lesion, and neuropsychological outcome.

Long-term neuropsychological recovery of 24 severe head-injured patients was examined and correlated with acute measurements of intracranial pressure (ICP) and diffuse computed tomographic (CT) lesions. Intracranial hypertension (ICP greater than or equal to 20 mm Hg) was present acutely in 12 patients and absent in 12 patients. CT diagnoses of diffuse swelling (DS) was present in 12 patients, and diffuse axonal injury (DAI) in 12 patients. During chronic recovery, neuropsychological dysfunctioning was found in all cases. Patients with acute ICP elevations showed more intellectual and memory losses than those without acute ICP elevations. No neuropsychological differences were found between patients with DS and DAI injuries. The findings suggest secondary brain insults caused by intracranial hypertension may be more disruptive to long-term neuropsychological functioning than diffuse lesion type.

Visual field defects in relation to head injury severity. A neuropsychological study.

A total of 159 head-injured patients were classified into four groups based on two acute categories of injury severity (minor-to-moderate and severe) and the subsequent presence or absence of visual field defects (VFDs). They were assessed neuropsychologically within ten to 19 months after injury. Within both minor-to-moderate and severe injury classifications, patients with VFDs were more impaired neuropsychologically and had more frequent acute secondary intracranial complications (brain swelling, intracranial hypertension, and cerebral hyperemia) than patients without VFDs. The findings suggest that the presence of VFDs during the long-term period may be residuals of acute secondary complications indicative of increased neuropsychological deficits after head injury.

Influence of injury severity on quality of survival after head injury.

The relationship between severity of injury [as determined by the Glasgow Coma Scale (GCS)] and the quality of survival (as determined by neuropsychological measurements and work return) were investigated in 54 conscious survivors within 16 months following head injury. While severely head injured (GCS less than or equal to 8) patients had more neuropsychological impairments in areas of intelligence, attention, memory, visuomotor speed, and motor skills than those with mild injuries (GCS greater than 8), performances after both types of injury were below normative levels in areas of learning, memory, and visuomotor speed. Unemployment increased after both severe and mild injuries, while employment status changed more frequently after severe injuries. Age had a minimal effect on neuropsychological and employment outcomes after minor head injuries (GCS greater than 13). The findings suggest that regardless of acute severity, closed head injury influences long-term quality of survival.

Influence of lesions detected by computed tomography on outcome and neuropsychological recovery after severe head injury.

Outcome at 6 months after severe head injury was determined in 117 patients whose computed tomographic (CT) examinations demonstrated diffuse axonal injury (DAI), diffuse swelling (DS), or focal injuries. Neuropsychological sequelae were ascertained from two examinations in 30 of the conscious survivors within the 1st year after injury. Outcome differences varied with the type of CT lesion. DS and focal injuries resulted in more favorable (good recovery) outcomes. Mortality was higher after DAI. Neuropsychological outcome varied with the type of CT lesion and the function measured. Overall differences in memory and learning were revealed among the three CT lesion categories, whereas differences in intelligence and visuomotor functions were not significant. Levels of memory, learning, and visuomotor speed were higher after DS injuries, but improvement was less. Greater improvement of memory, learning, and visuomotor speed occurred after DAI. After focal injuries, visuomotor speed improved, but not recall and learning. The results suggest that the type of injury incurred differentially influences the outcome and the neuropsychological aftermath of severely head-injured adults.

Relation of visual field defects to neuropsychological outcome after closed head injury.

Neuropsychological outcome within two years after injury was determined in 159 head injured patients who were classified into three groups according to the presence of either unilateral, bilateral, or no visual field defects (VFDs). The VFDs occurred irrespective of injury severity as determined by the Glasgow coma scale, or social outcome as determined by the Glasgow outcome scale. Differences among the three visual field groups were obtained for several neuropsychological functions: intelligence, memory, learning, acquired verbal skills, visuospatial skills, and visuomotor speed. Patients with bilateral VFDs were more severely impaired neuropsychologically than those with unilateral or no VFDs. Occurrences of secondary complications (brain swelling, intracranial hypertension, and hyperemia) were more prevalent among the bilateral VFD cases. The findings suggested that bilateral VFDs may be indicators of increased brain damage from secondary insults.

Relationship of acute CBF and ICP findings to neuropsychological outcome in severe head injury.

Neuropsychological outcome within 1 year after severe head injury was examined in 42 conscious survivors and correlated with acute measurements of cerebral blood flow (CBF) and intracranial pressure (ICP). During acute coma, CBF was elevated in 23 patients, indicating hyperemia, and was reduced in the remaining 19 cases. Intracranial hypertension (ICP 20 mm Hg or greater) was present acutely in 15 patients and absent in 27. Occurrences of hyperemia and intracranial hypertension were significantly related. During chronic recovery, neuropsychological dysfunction was found in all cases. However, patients with hyperemia revealed greater impairment of overall intellectual and memory functions than did those with reduced flow, while patients with intracranial hypertension showed greater memory deficit than did those without ICP elevations. The results suggest that early pathophysiological events can influence subsequent neuropsychological outcome, and that chronic recovery is not homogeneous in young severely head-injured adults.

Chronic low-level mercury exposure and neuropsychological functioning.

To measure the effects of chronic low-level exposure to inorganic mercury, the neuropsychological performances of 13 female dental auxiliary workers with elevated head mercury levels (as measured by an X-ray fluorescence technique) were compared with 13 workers with no measurable mercury levels. Workers with elevated mercury levels scored significantly less well on the Recurrent Figures, and SCL-90-R, but not on the WAIS, Rey's AVL, PASAT, BGT, Grooved Pegboard, and Finger Tapping tests. Chronic subtoxic levels of inorganic mercury appear to produce mild changes in short-term nonverbal recall and heightened distress generally, and particularly in categories of obsessive compulsion, anxiety and psychoticism, without alterations in general intellectual functioning, attention, verbal recall, and motor skills.

Lateralized psychological impairment associated with CT lesions in head injured patients.

Twenty-six adult patients with CT scans were given the Wechsler Adult Intelligence Scale (WAIS) during recovery from an acute head injury. Focal lesions were observed on the initial CT scans of 24 patients. These included 13 in the right hemisphere, 8 in the left hemisphere and 3 in both hemispheres. Diffuse cerebral swelling was observed in the remaining 2 patients. Both the standard WAIS examination (11 subtests) and a shorter version described by McFie (7 subtests) were used to assess psychological impairment associated with CT documented lesions. The McFie method involved a special scoring procedure that utilized reference subtests as an index of premorbid functioning. When mean algebraic differences between Verbal and Performance subtests were used, both methods differentiated left and right-sided lesions to a highly significant degree (p less than .001). Lateralized lesions yielded significant differences on 3 individual subtests (1 Verbal and 2 Performance) with the McFie method and on 6 individual subtests (all Verbal) with the standard WAIS procedure. Wechsler's Deterioration Quotient did not discriminate between groups. It was concluded that the traditional distinction between Verbal and Performance subtests on the WAIS was valid for CT documented lesions, and the shorter McFie version was as effective as the standard WAIS in lateralizing psychological dysfunction. Acknowledgements. This research was supported by Contract NS 5-2316 and Grant NS 08803 from the National Institutes of Health. We are grateful to Drs. Thomas A. Gennarelli and Howard I. Hurtig for patient referrals and neurological evaluations.

Correlation of long-term follow-up neurologic, psychologic, and cranial computed tomographic evaluations of head trauma patients.

We followed 153 head-injured patients by computed tomography and neurologic examinations. Twenty-seven also received psychologic evaluations. Cerebral parenchymal disruption was the abnormality produced by head trauma most likely to result in a fixed neurologic or psychologic deficit. Extracerebral hematomas and diffuse cerebral swelling were associated with deficits only if focal parenchymal damage was also present. Of the lesions encountered, midline hemorrhages, reflecting a diffuse shearing injury, were associated with the highest morbidity and mortality. The sites of residual parenchymal damage were associated more frequently with deficits found on psychologic testing than with neurologically detected deficits.

Spectrum subtraction technique for minimizing extracranial influence on cerebral blood flow measurements by 133xenon inhalation.

Estimates of regional cerebral blood flow (rCBF) by the 133Xe inhalation method are influenced by isotope contamination from slow clearing extracerebral tissues. Subtraction of x-ray (31 kev) from gamma-ray counts (81 kev) has been suggested as a means of yielding clearance curves that are relatively free of such contamination. In the present study, rCBF measurements based on the total 133Xe spectrum (x-ray plus gamma) were compared with those derived from the subtracted spectrum (x-ray minus gamma) in 20 young controls, using a two-compartmental analysis of the clearance curves. In comparison with addition, the subtraction data gave substantially higher estimates of blood flow for the slow (second) compartment. This, along with a shift in the relative weights of the two compartments, indicated a decreased contribution of slow tissue components, consistent with a reduction in extracerebral contamination. Blood flow values obtained by subtraction were in good agreement with those reported for the intracarotid injection method. A limitation of the subtraction technique, however, is the relatively high dose of isotope required for adequate signal-to-noise ratios.