Surgical site after resection of a meningioma.

PURPOSE: Our goal was to characterize MR changes over time at the site of meningioma resection in order to determine optimal timing for detecting residual and recurrent tumor. METHODS: Twenty-one patients were studied with enhanced MR imaging during the first 5 postoperative days and additional studies were obtained 3 to 8 weeks after surgery (16 studies), 3 months to 1 year after surgery (17 studies), and 1 year or more after surgery (32 studies). Images were analyzed for residual tumor, membrane enhancement, parenchymal enhancement, edema, and blood collections. RESULTS: Early postoperative images showed extensive, thin membrane enhancement that thickened by 3 to 8 weeks after surgery and that thinned or resolved and became less extensive by 6 months or more postoperatively. Twelve of 20 patients with long-term follow-up studies had membrane enhancement. Thin, serpiginous foci of enhancement in the surgical bed were identified only on early postoperative studies and probably represent gradual thrombosis of feeding vessels. CONCLUSION: Residual foci of meningioma are best detected on studies obtained within the first 5 days after surgery because membrane thickness increases by 3 to 8 weeks after surgery and may obscure a small residual meningioma. Our study confirms the presence of prolonged membrane enhancement after surgery, although it thins with time and becomes confined to the craniotomy site.

Differentiation between spinal tumors and infections with magnetic resonance imaging.

Distinction between spinal tumors and infections is a frequent clinical dilemma. To assess the accuracy of magnetic resonance imaging in distinguishing between spinal tumors and spinal infections, 30 patients with proven spinal tumors or infections were studied. Magnetic resonance imaging correctly diagnosed spinal tumors and infections in 29 of 30 cases (97%): 21 of 22 tumors were correctly diagnosed, and 8 of 8 infections were correctly diagnosed. The following points were learned: 1) The most consistent finding of vertebral osteomyelitis was the involvement of the disc space and adjacent vertebral body with decreased signal intensity on the T1-weighted images and increased signal intensity on the T2-weighted images. On the contrary, the disc spaces in tumor cases were uninvolved and demonstrated normal intensities on both T1- and T2-weighted images. 2) Loss of definition of the vertebral endplate was more common with infection than with tumor. 3) Contiguous vertebral involvement was seen more frequently in infections than in tumors. 4) Soft tissue changes were quite helpful: fat planes were obscured diffusely due to edema in infection, whereas fat planes were frequently intact, or obscured only focally, in tumors. 5) Cord compression was accurately diagnosed by magnetic resonance imaging in both tumors and infections. Magnetic resonance imaging was found to be superior to other imaging modalities in its ability to detect tumors or infections early and in providing information on the bone, disc, soft tissue, and neural structures.

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.

CT characteristics of intraventricular oligodendrogliomas.

Intraventricular oligodendrogliomas are a rare subset of oligodendrogliomas. Analysis of the clinical and CT characteristics of 11 cases in the literature and eight new examples revealed specific radiographic features, which included the presence of an anterior, midline mass within the lateral ventricles composed of clumped calcifications within a dense, enhancing matrix. Hydrocephalus is a constant feature, and these tumors present with signs of increased intracranial pressure. Eighteen of the 19 cases were benign and all were pure oligodendrogliomas, without admixture of other cellular elements. Intraventricular oligodendrogliomas grow slowly and are associated with prolonged survival but, due to their location, are difficult to remove and frequently require shunting. Subsequently developing symptoms, including herniation and death, are more frequently associated with complications related to hydrocephalus than with tumor growth. Intraventricular oligodendrogliomas can be distinguished from other intraventricular lesions by fairly specific CT characteristics. The ability to recognize them is helpful in prognosis, and awareness of associated complications related to hydrocephalus may assist in the long-term survival of affected patients.

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.

Transsphenoidal hypophysectomy: postsurgical CT findings.

Transsphenoidal surgery produces changes in the paranasal sinuses and sella that should be familiar to radiologists in view of the frequency of this type of surgery. Some of these changes, such as soft-tissue-density debris in the sinuses, are transient. Fat and other packing material identifiable in the sinuses and sella after surgery is permanent. The procedure is associated with a variety of complications that are readily detectable by computed tomography (CT). These include bleeding, compression of parasellar structures by packing material, cerebrospinal fluid leaks, and pneumocephalus. After a transsphenoidal procedure, with or without follow-up radiation therapy, residual enhancing intrasellar and parasellar lesions may still be identified.

Auditory evoked responses, impedance measures, and diagnostic speech audiometry in severe head injury.

Three case studies are presented to illustrate the clinical usefulness of serial electrophysiologic and behavioral audiologic assessments in describing CNS function in severe head injury. There was an association among acute auditory brain stem and middle-latency evoked response findings, computed tomography of brain abnormality and neurologic status, and rate of recovery. Auditory evoked response findings 4 days after injury were also correlated with long-term outcome of diagnostic speech audiometry.

Relation of cerebral blood flow to neurological status and outcome in head-injured patients.

Noninvasive studies of regional cerebral blood flow (CBF) were performed on 36 head-injured patients in varying degrees of coma, using the intravenous xenon-133 method. Serial examinations, averaging four per patient, were begun during the acute phase of illness and continued until death of recovery of normal consciousness. Comparison of the initial and final studies revealed that CBF declined to very low levels in all nine patients who died, and remained subnormal in a patient with persistent vegetative state. In contrast, 25 of 26 patients who recovered consciousness showed increases in blood flow. Because of the presence of both reduced and elevated blood flows on the initial study, CBF was not predictive of outcome. Absolute or relative hyperemia, observed in nine acute cases, was associated with either diffuse cerebral swelling (observed on computerized tomography) or recovery from systemic shock. Cerebral metabolic studies in hyperemic patients yielded a very low oxygen uptake and arteriovenous oxygen difference, indicating that the high blood flow was a true "luxury perfusion." When instances of presumed luxury perfusion were excluded, CBF was positively correlated with level of consciousness, assessed on a four-point coma scale.

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.

Computed tomography of post-traumatic extracerebral hematomas: comparison to pathophysiology and responses to therapy.

One hundred nine head-injured patients with epidural and acute and chronic subdural hematomas were evaluated by computed tomography (CT). Eighty-two patients had subsequent CT examinations in order to evaluate postoperative changes and responses to therapy. Results seen on CT studies were compared to patients' neurologic status at the time of scanning. The rapid return of the appearance of the brain and the patients' neurologic status to normal soon after evacuation of an uncomplicated epidural hematoma reflect the lack of parenchymal damage. In contrast, acute subdurals are usually produced by associated contusions or cortical lacerations. The mass effect of these parenchymal lesions is responsible for a degree of ventricular shift out of proportion to the usual small size of the acute subdural. Small acute subdurals managed medically and residual collections found after evacuation resolved spontaneously. No acute subdurals progressed to a chronic subdural. The latter are infrequently associated with cerebral parenchymal injury and their symptoms are due to the size of the collections. Deformity of the underlying brain by the chronic process and slow re-expansion of the brain account for the common finding of a slowly resorbing, residual fluid collection following surgical evacuation.

A sign of subarachnoid bleeding on cranial computed tomograms of pediatric head trauma patients.

Of 109 children examined by cranial computed tomography soon after an acute head injury, a density in the region of the falx was identified in 24 patients, but disappeared on subsequent studies. The density measures in the range of blood and is thought to represent subarachnoid blood. It can be confused with falx calcification in adolescents and adults, but falx calcification is normally not seen in the pediatric population.

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.

Computed tomography of intracerebral hematomas. I. Transmission CT observations on hematoma resolution.

Changes in the size and density of intracerebral hematomas were investigated by analyzing the sequential CT studies of 40 patients. Intracerebral hematomas decrease in density by an average of 0.7 EMI units per day. The dense portion of the hematoma decreases in size by an average of 0.65 mm per day. Mass effect does not decrease in proportion to the decrease in size of the dense portion of the hematoma but is delayed. The only instances of increasing mass effect occurred in patients undergoing surgical evacuation of the hematoma and in those who sustained trauma. Posthematoma residua include decreased parenchymal density, focal atrophy, and ventricular enlargement.

Computed tomography of intracerebral hematomas. II. Radionuclide and transmission CT studies of the perihematoma region.

Transmission CT studies of 40 patients with intracerebral hematomas were used for an analysis of the perihematoma region. Nineteen of these patients had radionuclide studies. In the brain adjacent to an intracerebral hematoma, the patterns of pertechnetate uptake on scintillation scans and contrast enhancement on transmission CT resemble those observed in cerebral infarctions. The healing of the perihematoma region proceeds similarly to that of infarcts. The brain about the hematoma is ischemic tissue which behaves much like cerebral infarction not related to hematomas.