Ultrasound assesses brain trauma

Ultrasound can accurately predict elevated intracranial pressure, according to a study presented at the 2005 American Institute of Ultrasound in Medicine meeting.

Prompt detection of increased intracranial pressure (ICP) in unconscious trauma patients may help emergency physicians make critical management decisions, sort out treatment priorities, and avoid unnecessary tests. ICP can signal or lead to several neurologic conditions:

• brain compression and swelling

• hydrocephalus and spinal fluid accumulation

• epidural and subdural hematoma

The clinical literature points at CT as the standard of care for ICP diagnosis. Dr. Vivek Tayal and colleagues at the Carolinas HealthCare System in Charlotte, however, hypothesized that ultrasound measurement of the optic nerve sheath diameter (ONSD) could anticipate CT findings.

The investigators applied the technique on 55 patients with head trauma prospectively enrolled in the study. They found that ultrasound gauging of the ONSD correctly predicted all cases of increased ICP diagnosed by CT.

The researchers applied a 7.5-MHz ultrasound probe on the closed eyelids of all subjects and evaluated the ONSD 3 mm behind the globe. An ONSD of 5 mm or greater was considered abnormal.

All seven patients who showed signs correlating with elevated ICP on CT also showed a mean ONSD of 6.27 mm. Bedside ultrasound for ICP detection with an ONSD cutoff of 5.5 mm showed a sensitivity, specificity, and positive predictive value of 100%, 86.4%, and 53.9%, respectively.

Bedside ONSD ultrasound could become a helpful screening test for the diagnosis of elevated ICP, especially considering that the clinical assessment of ICP may be unreliable, the investigators said.

For more information from the Diagnostic Imaging archives:

Ultrasound streamlines emergency medicine

Studies explore strategies for emergency room MSCT

Underserved areas ring up for long-distance ultrasound interpretation

Radiology must change to retain ultrasound role