[size=20px]A 14 year old girl is admitted to the ICU after she was struck by a car as a pedestrian. She is intubated and has a GCS of 7 with a closed head injury and a temporoparietal skull fracture. She has several lacerations and contusions on her scalp. A small amount of blood is pooled in the right ear, but a double ring/halo sign is negative. The best test of the fluid to determine if the fluid is CSF is

 

A Glucose

 

B Albumin

 

C Beta-2 transferrin

 

D Hemoglobin[/size]

(Untitled)

 

C

C

correct

 

Most CSF leaks are due to trauma, and present as otorrhea or rhinorrhea. They may be positional and intermittent. Since blood and CSF have different densities and will migrate at different rates on an absorptive surface, a "halo" or ‘‘double ring’’ of central blood, surrounded by a second ring of CSF is sometimes seen. False positives from saliva, tears, or other fluids can occur.

 

Beta‐2‐transferrin is a protein produced by neuraminidase activity in the brain which is uniquely found in the cerebrospinal fluid (CSF) and perilymph. Its absence in other body secretions makes its detection invaluable in diagnosing a CSF leak.[1] First identified in 1979, beta-2 transferrin is now the most sensitive and specific way to identify cerebrospinal fluid.

 

Most traumatic leaks resolve spontaneously, but CSF diversion with a lumbar drain or serial lumbar punctures is sometimes necessary, with success rates of 70 - 90%, and with a mean of about 7 days until resolution.

 

The other tests mentioned would not be useful.