While most cases of suspected concussion do not require imaging, it is appropriate for patients like this 52-year-old man, who had a history of assault and presented with dizziness and vomiting. His CT scan revealed mild hyperattenuation adjacent to the cranial shadow—a finding suggestive of a subarachnoid hemorrhage in the region.
When trauma’s an old story
Patients with head injury do not always seek emergency care. Whenever an office patient tells you about a head injury, however minor it seems, you should always assess for concussion. The diagnosis may be useful in guiding treatment and prevention strategies in the future. It may also help you recognize post-concussive symptoms, which can occur weeks or months after the trauma and cause significant morbidity.
Does your patient really need imaging?
Imaging is usually not necessary for diagnosis when the mental status and neurologic examinations are negative. Abnormal imaging scans are rare in cases of suspected concussion, showing up in fewer than 10% of computed tomography (CT) scans and 30% of magnetic resonance images (MRIs).11 You wouldn’t order imaging for Max, as he passed his neurologic exam with flying colors. However, if he had remained unconscious for a longer period, his mental status changes had continued, or he had neurologic symptoms that persisted for more than a week, you would order neuroimaging to rule out additional pathology.10,12 Neuroimaging may also be indicated in cases of particularly forceful injury—a fall from a height greater than 3 feet, for example, or a pedestrian hit by a car—or for a patient with an open, depressed, or suspected basal skull fracture.
In addition, imaging studies should be done for patients with a score of less than 15 on the Glasgow coma scale, retrograde amnesia for more than 30 minutes before the accident, or more than 2 episodes of vomiting. Imaging options include a CT scan without contrast to evaluate for intracranial bleeding or an MRI without contrast to test for smaller intracranial bleeds or axonal injury.13,14
CT scans are quick, generally available, and reasonably inexpensive, but may not detect all relevant abnormalities. MRIs are more sensitive and better able to detect areas of contusion, petechial hemorrhage, and axonal injury, but are less accessible in emergencies and cost a great deal more.13,14
New research suggests that patients with prolonged neurologic sequelae may benefit from single proton emission computed tomography (SPECT) or positron emission tomography (PET) in addition to conventional CT and MRI studies.13,15 SPECT studies use radioactive tracers that can cross the blood-brain barrier to estimate cerebral blood flow; decreased cerebral blood flow indicates areas of brain damage.11 PET scans are more expensive than SPECT, but have the advantage of being able to demonstrate oxygen and glucose metabolism, which are more sensitive indicators of brain damage. While SPECT and PET images are seldom used in diagnosing concussion, they can benefit patients who continue to have neurologic deficits that require further definition of the areas of brain injury.
How to fine-tune concussion care
First, grade the concussion. Concussion scales are a useful guide for making treatment decisions.4,5,10 The AAN scale presented in TABLE 1 is the most widely used. Keep in mind, though, that this scale is scheduled for revision.1
You conclude from your examination of Max that he does have a concussion, and that his loss of consciousness indicates a grade 3, even though his symptoms of dizziness and confusion lasted less than 15 minutes.
Initiate monitoring. This essential aspect of concussion management can take place at home for most patients, with hospitalization necessary for only a few. Max can go home. You know his parents well, and they’re competent to follow a monitoring protocol. For the first 24 hours, you tell them to wake Max up every 2 hours, so that they can pick up any change in his symptoms without delay. If they have difficulty waking him or he develops signs and symptoms such as vomiting or severe headache, you tell them to call you and bring Max back to the hospital.
Patients who should be monitored in the hospital are those with seizures, evidence of intracranial bleeding or cerebral edema on CT scan, or a history of taking oral anticoagulants. So should any patients whose living situation is not reliable for adequate home monitoring—homeless patients or those with a chaotic home life, for instance.