Mild Brain Injury: Introduction | Definitions | Epidemiology | Pathophysiology | Sequelae of mTBI | Is There a Postconcussive Syndrome? | Predictors of Incomplete Recovery | Functional Disability | Treatment Issues | Key Clinical Points | Recommended Readings | References
Severity of brain injury exists along a broad continuum
(see Chapter 2, Neuropathology). Discerning the extent of injury
neuropathology in humans is limited to examination of the brain
either at autopsy or indirectly through neuroimaging. This has resulted
in efforts to classify brain injury severity on the basis of clinical
signs and symptoms evident at the time of injury or shortly thereafter.
This approach does not take into account the forces that contribute
to the injury, measures of associated neuropathology, or ultimate
functional outcome. Thus, these efforts are at best an approximation
of injury severity. Nevertheless, over the last several decades
it has become the convention to categorize injury severity into
three groups: mild, moderate, and severe, based on initial presentation.
At the more severe end of the injury spectrum, the correlation between
initial injury severity rating and various outcome measures is relatively
robust (Rassovsky et al. 2006). At the milder end of
the spectrum, this correlation is less tight, and over the last
100 years (Evans 1994) this has generated confusion
with regard to the typical presentation, trajectory of recovery,
and outcome of milder injuries. Interest in this topic has grown
dramatically since the last edition of this book—about
one-fifth of the papers published on mild traumatic brain injury
(mTBI) in the past 60 years appeared in the last 5 years.
This chapter presents an overview of issues pertinent to mild brain