43 year old female with no previous medical history was brought to the hospital after a motor vehicle accident. She was found to be unresponsive at the scene. The patient was put on the ventilator and CT scan of her head was ordered. CT scan revealed some subarachnoid hemorrhage due to the head injury, otherwise no acute findings. No injuries to the chest, abdomen or pelvis were detected.

Traumatic brain injury (TBI) remains the leading cause of death in the US for individuals between the ages of 1 and 45 years. TBI often leads to significant disability and has a huge socioeconomic impact.

TBI is being classified depending on the prevailing pathological mechanism identified with neuroimaging – primarily CT scan of the head and MRI scan of the brain. Some head injuries, like subdural or epidural hematomas, may require neurosurgery.

The patient above remained unresponsive one week after the accident. Tracheostomy and a feeding tube were inserted. Repeat CT scan of the brain showed some improvement in the extent of the traumatic subarachnoid hemorrhage, yet no new pathology to explain the patient’s poor clinical status.

MRI of the brain was performed and revealed evidence of the Diffuse Axonal Injury (DAI). DAI is a common result of traumatic deceleration injuries and commonly seen after high-speed motor vehicle accidents. The leading pathological mechanism is the disruption of the axons – connections between the nerve cells in the brain.

DAI if often missed or underappreciated on the CT scan since the primary changes happen on the microscopic level. MRI brain is the study of choice to diagnose DAI.

Despite it’s “underwhelming” presentation on the neuroimaging studies, DAI remains a serious cause of morbidity. 90% of patients with DAI remain in a persistent vegetative state. DAI rarely causes death since the brainstem function remains intact.

The injury to the brain is most significant in the areas where the density difference is the greatest. Most DAI lesions, for this reason, occur at the gray-white matter junction. The primary injury often precipitates a cascade of adverse changes on the cellular level leading to further brain damage and atrophy.

The patient remained unresponsive and was transferred to a nursing facility for further treatment.