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Repetitive Head Injury Syndrome David Cifu, MD, eMedicine.com (page 3 of 8) Page 3 of 8

Imaging Studies

Imaging studies are reserved for athletes with more significant injuries, such as those that cause loss of consciousness, persistent symptoms, neurologic deficits, or neurologic deterioration. Imaging studies should be considered in all athletes who have had more than 1 concussion. In addition, imaging studies should be ordered if symptoms last longer than 12 hours. Consultation with a neurosurgeon is imperative if any imaging findings are abnormal.

• Plain skull radiography yields few findings in persons with mild brain trauma, and it should not be ordered unless facial fractures are suspected. Plain film radiography (cervical spine [C-spine] radiographs) can be ordered to rule out neck pathology, which can occur with head trauma.
• Head computed tomography (CT) scanning is sensitive for detecting intracranial pathology associated with blunt-force trauma, even in a mild head injury (eg, Glasgow Coma Scale score of 13-15).
  • Nonenhanced CT scanning is the imaging examination of choice because acute hemorrhage must be excluded before performing contrast-enhanced CT scanning.
  • The advantages of CT scanning compared with MRI include (1) more rapid image acquisition in an emergency situation; (2) better depiction of bone; (3) lower cost, although cost should not influence clinical decision making in a potentially life-threatening situation such as the setting of a head injury; (4) correlation of negative results with a successful outcome; and (5) better sensitivity in detecting skull fractures.
  • Compared with the initial (first 12-24 h) head CT scan, the follow-up CT scan may better reveal small hemorrhages, which coalesce to form a brain contusion.
  • CT scanning can depict acute hemorrhages, skull fractures, cerebral edema, and cerebral herniation. An acute subdural hematoma is approximately 3 times more common than an epidural hematoma in sports-related head injuries.
• MRI of the head is more sensitive than CT scanning for detecting subtle changes such as small hemorrhages, edema, and diffuse axonal injury (DAI).
  • MRI should not be ordered in emergency situations because CT scanning is faster than MRI and has the advantages listed above.
  • The advantages of MRI compared with CT scanning include the ability of MRI to better depict subtle edema, small hemorrhages, arteriovenous malformations, and DAI.
  • DAI is seen in severe head injuries and is thought to result from the shearing of multiple axons. DAI is represented on MRIs as diffuse, high-signal intensity specks in the white matter.
  • MRI should be ordered if the patient's symptoms persist and CT scanning results are normal or if the symptoms are atypical or worsen despite normal or stable CT scan findings.

Other Tests

• Neuropsychologic testing
  • This is an in-depth examination of the injured athlete's thought processes and is considered the criterion standard for the initial and follow-up assessment of concussion patients, especially those with SIS.
  • A neuropsychologist certified by the American Board of Professional Psychology is the best resource for these assessments, and a consultative approach is preferred, as opposed to merely a description of test data.
  • A range of cognitive and behavioral tests are used, based on the preferences of the neuropsychologist, the severity of the injury, the specific clinical issue at hand (eg, return to school, return to work, manage finances), the educational and cultural background of the examinee, and the time post injury.
  • The occurrence of multiple concussions is associated with reduced cognitive performance on neuropsychologic tests.
  • Hinton-Bayre et al showed that impaired performance on psychometric tests continued even after the athletes (professional rugby players) were symptom free.²⁵
  • Electroencephalography (EEG)
  • EEG yields conflicting and typically nonspecific results. Most of the research with EEG has involved boxers.
  • Busse and Silverman showed that 37% of abnormal EEG findings occurred in boxers who have had a concussion.²⁶
  • Kaplan and Browder studied 1400 electroencephalograms in boxers and found that 34% of the athletes had normal EEG findings.²⁷ The authors concluded that fighters with a lower ring rating had a higher percentage of disorganized EEG findings.
  • Johnson used EEG to evaluate retired professional boxers and found chronic brain damage in 12 of 15 of these individuals 22 years after their careers had ended.¹⁵

 

• Other studies show abnormal EEG findings in 20-30% of boxers.
• However, early studies by Beaussart and Beaussart-Boulenge did not find any correlation between EEG changes and the severity of postconcussion syndrome in 3100 cases.¹⁴
• Dynamic imaging
  • Single-photon emission computed tomography (SPECT) scanning and positron emission tomography (PET) scanning have high sensitivity, but the specificity of these modalities is unclear and the clinical correlation is limited. At present, these tests are used primarily for research activities.
  • In addition, these examinations are expensive and not easily available to most clinicians.
  • Results from these tests may be overinterpreted or underinterpreted in medicolegal settings; the use for these types of activities should be discouraged until further definitive research is performed and has undergone peer review.

Procedures

• ICP monitoring may help in severe TBI, but it has limited usefulness in patients with mild TBI.
• Patients with an ICP greater than 25 mm Hg generally have more unfavorable outcomes than those with lower ICP measurements.

From eMedicine.com. Reprinted with permission. www.emedicine.com/sports/TOPIC113.HTM.

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