Delayed nonhemorrhagic encephalopathy following mild head trauma. Case report

Transiently increased basilar artery flow velocity following severe head injury: a time course transcranial Doppler study

BACKGROUND AND PURPOSE

Transcranial Doppler ultrasonography has been used to study changes in cerebral hemodynamics following head injury. However, most studies evaluated the anterior circulation and little information exists on transcranial Doppler of the vertebrobasilar arteries after head injury.

METHODS

Thirty-two patients with a Glasgow Coma Scale (GCS) score between 4-8 and 11 patients with a GCS score between 9-14 were studied using transcranial Doppler ultrasonography for the first 10 days after injury. Daily variations in the mean blood flow velocities of all major cerebral arteries were recorded.

RESULTS

In patients with GCS score between 4-8, the mean blood flow velocities in the middle cerebral and basilar arteries gradually increased beginning on day 2 postinjury and peaked on the 4th-5th day after injury. Those changes were more prominent, and appeared earlier, in the basilar artery. The ratio between the mean flow velocities of the middle cerebral artery and the basilar artery during the first 4 days was significantly lower than in normal controls, indicating a particular increase of flow velocity in the basilar artery. Nineteen out of 32 patients (60%) with severe head injury showed mean blood flow velocity increased over 75 cm/sec in the basilar artery. Mean blood flow velocity >90 cm/sec in the basilar artery, compatible with vasospasm, was observed in 12 of 32 patients (37%). Spasm in the middle cerebral artery was observed in 12 (37%) of patients; 10 of them also had evidence of basilar artery spasm. On the whole, 14 of 32 (43%) patients had evidence of spasm either in the middle cerebral or basilar arteries or in both. In 5 of 11 patients (50%) with moderate head injury (GCS score 9-14), blood flow velocity in the basilar artery greater than 75 cm/sec was observed, but in only two of them it reached the values over 90 cm/sec. Vasospasm in the middle cerebral artery was noted in one patient.

CONCLUSIONS

A significant number of patients develop increased flow velocities compatible with vasospasm in the basilar artery after severe head injury. This phenomenon may represent an additional factor that contributes to the poor outcome of severely head-injured patients.

Delayed and progressive brain injury in closed-head trauma: radiological demonstration

The importance of delayed or secondary brain insults in the eventual outcome of closed-head trauma has been documented in experimental models. To understand this phenomenon in the clinical setting, we studied a series of head-injured patients in whom multiple cranial computed tomographic (CT) scans were obtained. Patients whose follow-up CT studies revealed new intracranial lesions or worsening, compared with admission findings, were considered to have delayed cerebral injury. One hundred forty-nine (44.5%) of 337 consecutively studied patients developed delayed brain injury. There were highly significant associations (P < 0.001) between the appearance of delayed cerebral insults and the severity of the initial brain injury, the need for cardiopulmonary resuscitation in the field, the presence of coagulopathy at admission, and subdural hematoma on the initial CT scan. In addition, delayed injury was associated (P < 0.001) with higher mortality, slowed recovery, and poorer outcome at 6 months. Delayed brain injury was not significantly associated with patient age, sex, injury mechanism, associated injury, the need for endotracheal intubation in the field, early talking, CT abnormality other than intracranial hematoma, or type of residual neurological deficits. We used multiple regression analysis to explore the relationship between severity of injury, delayed insults, and outcome. As expected, the severity of the initial brain trauma contributed significantly to neurological outcome. The presence of delayed cerebral injury makes the outcome dramatically worse for each category of initial injury severity. The relationship between initial and secondary brain injury is discussed.

Delayed brain injury after head trauma: significance of coagulopathy

We reviewed the records of 253 patients with head injury who required serial computed tomographic (CT) scans; 123 (48.6%) developed delayed brain injury as evidenced by new or progressive lesions after a CT scan. An abnormality in the prothrombin time, partial thromboplastin time, or platelet count at admission was present in 55% of the patients who showed evidence of delayed injury, and only 9% of those whose subsequent CT scans were unchanged or improved from the time of admission (P less than 0.001). Among patients developing delayed injury, mean prothrombin time at admission was significantly longer (14.6 vs. 12.6 s, P less than 0.001) and partial thromboplastin time was significantly longer (36.9 vs. 29.2 s, P less than 0.001) than patients who did not have delayed injury. If coagulation studies at admission were normal, a patient with head injury had a 31% risk of developing delayed insults. This risk rose to almost 85% if at least one clotting test at admission was abnormal (P less than 0.001). We conclude that clotting studies at admission are of value in predicting the occurrence of delayed injury. If coagulopathy is discovered in the patient with head injury early follow-up CT scanning is advocated to discover progressive and new intracranial lesions that are likely to occur.