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One thousand consecutive head injuries were evaluated in a 14-month period. Computerized tomography (CT) was performed in 316 patients and 200 (63%) were scanned within 72 hours of injury. Fifty-one percent of patients had abnormal scans. The yield of abnormal scans varied with the neurological state at the time of the scan: alert and normal neurologically, 13%; alert and focal deficit, 50%; impaired consciousness and no lateralizing findings, 35%; impaired consciousness and lateralizing findings, 85%; deep coma or posturing, 56%. Thirty-eight percent of patients had multiple lesions. Repeat scans were done in 103 patients, 52% developed new lesions or deterioration in known lesions, and 31% required subsequent surgery. Ten patients developed delayed onset subdural hygromas noted six to 46 days after injury. Two of eight operated patients improved markedly. The CT scan appearance of subdural lesions may be independent of the time from injury depending upon initial composition and rebleeding episodes. Thus, subdural lesions should not be labeled "acute," "subacute," or "chronic" on the basis of CT morphology alone. Seven patients had subdural lesions with the same density as brain (isodense). Arteriography aided diagnosis in six patients. The CT scan readily shows what proportion of a parenchymal lesion is intracerebral hematoma, contusion, or edema, rather than nonspecific arteriographic mass effect, and allows precise surgical decisions. Eighteen of 40 patients (45%) with "brain stem contusion" harbored surgical lesions, including five cases of delayed subdural hygroma.

The deficiencies of cranial computed tomography in the evaluation of craniocerebral injury may be categorized as: problems with the patient (cervical spine injury, motion artifact, airway control, head tilt, metallic foreign bodies); the incomplete scan; failure to determine the attenuation coefficient; failure to perform contrast enhancement; and failure to perform cerebral angiography. Increased awareness of these shortcomings of computed tomography and the selected use of cerebral angiography will ensure more accurate detection of the various abnormalities encountered in traumatic pathology.

The CAT Scan is capable of providing a diagnosis in many cases. It has an overall accuracy rate of 95 to 98 percent for diagnosis of a lesion versus no lesion. The CAT scanner has proven to be the single most important advance in neuroradiology in recent years. It is the least traumatic, the safest, and most definitive of the neurological procedures.

A 9-week-old infant manifested continuous vomiting for 1 week accompanied by a tense fontanel, "sun setting" of the eyes, frequent opisthotonos, and hypertonicity. The head circumference was at the 50th percentile. Computerized tomography (CT) revealed acute hydrocephalus and a posterior fossa subdural hematoma. The brain stem and cerebellum were of greater density (54 Hounsfield units) than normal cerebral white matter (42 Hounsfield units) whereas the subdural hematoma was the same density as normal cerebral white matter ("isodense"). The cerebellum and brain stem became enhanced by contrast (68 Hounsfield units), but no enhancement occurred in the cerebral white matter or subdural hematoma. A shunt followed by occipital craniectomy resolved both the hydrocephalus and subdural hematoma. Repeat CT scan 15 days postoperatively disclosed continuing higher density of the cerebellum and brain stem (60 Hounsfield units) relative to cerebral white matter. Increased density of the infantile cerebellum has been noted previously but not to the same extent as in this patient.

The radiographic evaluation of a spectrum of vascular cerebral damage is presented, ranging from simple porencephaly to the most severe form, classic hydranencephaly. With a combination of clinical materal and computed tomography, it is possible in most cases to arrive at a specific diagnosis of hydranencephaly or severe bilateral porencephaly. Pictorially similar entities, such as massive congenital subdural hematomas or hygromas, alobar holoprosencephaly, massive hydrocephalus, and massive postanoxic or infective encephalopathies, are discussed.

Retrospective analysis of 200 cases of documented head trauma demonstrated an accuracy approaching 100% in the diagnosis of intra- and extracerebral collections of blood. Caution must be exercised in the evaluation of trauma 1 to 5 weeks old, since subdural hematomas have the same density as normal brain tissue, and angiography may be necessary. The clinical diagnosis of brainstem contusion is associated with a remarkably high level (54%) of surgically correctable lesions. The use of computed tomography in the evaluation of other traumatic intracranial lesions is discussed.