Abstract
Objectives: A depth of lesion (DOL) model using brain imaging has been proposed to aid in medical decision-making and planning for rehabilitation resource needs. The purpose of this study was to determine the early prognostic value of a DOL classification system for children and young adults following severe traumatic brain injury.
Methods and Outcome measures: CT/MRI brain imaging studies on 92 patients, aged 3 to 21, admitted to the Kluge Children's Rehabilitation Center, University of Virginia, were evaluated to determine DOL. Images were classified according to 5 DOL levels (cortical to brainstem). Functional outcomes in mobility, self-care, and cognition, as rated on the WeeFIM instrument, were compared by DOL levels.
Results: Admission WeeFIM scores were significantly different for the DOL levels with the highest score for frontal and/or temporal lesions and the lowest for lesions including the brainstem or cerebellum (P < .001). However, the deeper the lesion, the greater the functional gains (P = .05), resulting in discharge WeeFIM scores that were not significantly different across DOL levels. Patients with deeper lesions tended to have longer lengths of stay in rehabilitation but were able to "catch up" with patients who had more superficial lesions.
Conclusions: While relatively simple and convenient, the DOL classification system is limited in its usefulness as an early prognostic tool. It may not be possible to predict outcome in the early acute phase in the intensive care unit on the basis of standard brain imaging alone. Patients with deeper lesions may enter rehabilitation at a more impaired level but can make remarkable progress, though it may take longer than for less severely injured individuals.
PARENTS and clinicians want to know the prognosis for recovery during the early acute phase of severe traumatic brain injury (TBI). While various scoring systems utilizing both single and multiple variables have merit, they often require extraordinary effort, technology, or expertise that might not be available in many clinical settings. Therefore, we wished to determine whether standard brain imaging alone, readily available and almost universally obtained, would be a suitable prognostic tool in severe TBI in children.
TBI accounts for 1 million visits to hospital emergency departments each year, nearly a quarter of a million hospitalizations, and 50,000 deaths in the United States. 1 The risk of TBI is highest for male adolescents involved in car accidents. Children under 5 years of age are also at high risk from falls and nonaccidental trauma. In general, more severe brain injury is associated with poorer motor and cognitive outcome. Sixty-five percent of children with severe TBI survive. 2,30 Twenty percent of survivors are left with disability. 4
Neuroimaging is an essential diagnostic procedure in pediatric TBI. 5 While computerized tomography (CT), typically the first brain imaging technique to be used in the immediate postinjury stage, is useful for demonstrating scalp, bone, extra-axial hematomas, and parenchymal injury, magnetic resonance imaging (MRI) is more sensitive for all posttraumatic lesions other than skull fractures and subarachnoid hemorrhage. 6
MRI is particularly sensitive in detecting diffuse axonal injury (DAI), including the nonhemorrhagic type. 7 Nevertheless, both CT and MRI scans have been shown to have prognostic value. 8 Skull fractures seem to be associated with increased mortality, whereas the type of brain lesion is related to disability among survivors. 9 Both DAI and deep lesions are said to correlate with more severe impairment. 10-12
Follow-up MRI 6 to 18 months postinjury can show significant abnormalities not previously seen, such as ventricular enlargement, correlating highly with poor outcome. 10 Undoubtedly, these late findings reflect a summation of primary and secondary brain injury.
A number of schemes for summarizing imaging manifestations of brain injury have been developed. These schemes have incorporated descriptions of the distribution and number of abnormalities. 8,13,14 Ommaya and Gennarelli developed a depth-of-lesion model in animals that has been applied to humans and appears to be a useful predictor of outcome. 15 Grados et al found such a classification to be significantly correlated with Glasgow Coma Scale severity, number of lesions, a disability rating scale, and speed of injury. 16 Similarly, Levin et al found that the greater the depth of lesion, the worse the outcome measured on the Glasgow Outcome Scale and Vineland Adaptive Behavioral Scale. 17 Deep lesions correlate with greater psychological impairment, 18 persistent vegetative states after TBI in adults, 11 and greater impairment of consciousness on hospital admission. 12 These studies used MRI results obtained at least 3 months following injury.
The purpose of this study was to determine whether depth of lesion observed on CT and/or MRI of the brain obtained acutely predicted early functional recovery as measured by the WeeFIM following TBI in children, adolescents, and young adults. If so, such an approach to early prognostication could be useful for treatment decisions and rehabilitation planning in the intensive care setting.