164.The answer is d.(Rosen, pp 613-623.)Cauda equina syndromeis
an injury to the lumbar, sacral, and coccygeal nerve roots, causing periph-
eral nerve injury that can lead to permanent neurologic defects if not recog-
nized and corrected rapidly. Because of the central location of the disk
herniation, symptoms are often bilateral and involve leg pain, saddle anes-
thesia, and impaired bowel and bladder function (retention or inconti-
nence). On examination, patients may exhibit loss of rectal tone and display
other motor and sensory losses in the lower extremities. Patients with sus-
pected cauda equina syndrome require an urgent CT scan or MRI.
(a)Abdominal aortic aneurysms (AAA) can present with low back
pain and rarely a neurologic deficit if they get large enough and impinge a
nerve root. AAA should always be considered in patients over 50 years with
hypertension and low back pain. A bedside ultrasound can usually identify
large abdominal aortic aneurysms. If there is still concern for an AAA, a CT
scan can rule the diagnosis out. (b)Disk herniation can result in peripheral
nerve root compression and irritation leading to sensory and motor
deficits. Patients, however, should not exhibit altered bowel and bladder
function, or have decreased rectal tone. If so, the condition is likely cauda
equina syndrome and is a neurologic emergency. (c)Spinal stenosis is nar-
rowing of the spinal canal, which may cause spinal cord compression that typ-
ically is worse with back extension and relieved with flexion. (e)Osteomyelitis
is an infection of the bone that typically presents with fever.
165.The answer is d.(Rosen, p 295.)A unilateral dilated pupilin the
setting of head trauma is an indicator of increased ICP.If ICP is not low-
ered immediately, the patient has little chance of survival. Hyperventilation
to produce an arterial PCO 2 of 30 to 35 mm Hg will temporarily reduce
ICP by promoting cerebral vasoconstriction and subsequent reduction of
cerebral blood flow. The onset of action is within 30 seconds. In most
patients, hyperventilation lowers the ICP by 25%. PCO 2 should not fall
below 25 mm Hg because this may cause profound vasoconstriction and
ischemia in normal and injured areas of the brain. Hyperventilation is a
temporary maneuverand should only be used for a brief period of time
during the acute resuscitation and only in patients demonstrating neuro-
logic deterioration.
(a)ED cranial decompression (burr hole) should only be performed
under extreme circumstances when all other attempts at reducing ICP have
failed.(b)There is no evidence that steroids lower ICP and are not recom-
mended in head trauma. (c)Furosemide has no role in acute traumatic
Trauma Answers 175