Assessment and Treatment

The most effective way to evaluate a person with a possible MTBI is through the comprehensive use of neurorehabilitation specialists. This team of specialists includes neurology, physiatry, neuro-ophthalmology, developmental optometry, neuropsychology, neuro-otology, physical therapy, occupational therapy, speech pathology, and counseling/psychotherapy. This level of expertise in conjunction with a good case manager, brought together soon after the person is injured, is usually very effective in detecting and treating MTBI, before the situation can deteriorate or become a chronic, debilitating condition.

Neurodiagnostic Tools

It is important to recognize that a single neurodiagnostic test alone cannot be used to diagnose or rule out MTBI.

CT (computerized tomography): In the emergency department, CT is primarily used to evaluate acute TBI. CT scans detect acute hematomas and other areas of hemorrhage.

MRI (magnetic resonance image): This tool provides greater definition of lesions than the CT scan. Cellular density as well as water diffusion and blood perfusion is assessed. MRI is the best tool to evaluate neurological changes in the post-acute phase of recovery.

fMRI (functional magnetic resonance image): This is a new diagnostic tool that produces brain mapping to demonstrate metabolic changes in brain tissue as the person performs functional tasks (i.e., reading, listening, mental math, imaging, etc.). It has been recently used in studies correlating neuropsychological findings with metabolic-perfusion changes in the brain following MTBI.

PET (positron emission tomography): This imaging technique provides a view of the brain's metabolic status. Reduced metabolism has been found in the frontal and temporal lobes after some cases of MTBI.

PET scan data is also consistent with results from neuropsychological evaluations. It has also been found that minor TBI without loss of consciousness can result in significant, functional brain damage.

SPECT (single-photon emission computerized tomography): This tool detects areas of decreased cerebral blood flow, which assists in diagnosing persistent post-concussion syndrome beyond three months post-injury. SPECT is less expensive, less complex, and more available than a PET scan. SPECT neuroimaging provides evidence of the type of damage that often leads to post-traumatic headaches.

The literature provides ample information regarding the use of CT, MRI, SPECT, and PET scans. In general, MRI and SPECT imaging provide greater definition. When neurological examinations are not consistent with CT-scan findings, an MRI is often beneficial in detecting axonal-shear injuries not found on a CT scan. It has also been shown that if an abnormality is found on a CT scan a "complicated" MTBI is involved. This finding signifies a worse neurobehavioral recovery profile compared to other MTBI.

Standard EEG (electroencephalogram) and QEEG (spectral analysis/quantitative EEG): The EEG measures electrical activity of the brain. Seizures can occur following MTBI. Occasional findings indicate evidence of partial, complex seizures. In recent years, the QEEG has been gaining favor in the diagnostic evaluation of MTBI by using high-speed computers to quantitatively measure brain activity.

Some have proposed the "marriage" of the MRI's capacity to view structural features of the brain with the QEEG's capacity to measure electrical and magnetic features to determine the results of rapid acceleration/deceleration-type injuries. One hundred percent accuracy has been reported in QEEG's ability to differentiate between normal brain activity and MTBI, up to one year post-injury. Significant effects have been located in the frontal lobes and posterior areas of the brain. These findings thus indicate that "time does not always heal."

There are also neurodiagnostic tools to detect vestibular dysfunction and related visuomotor (oculomotor) abnormalities. It is important to determine peripheral vs. mixed dysfunction in order to provide treatment guidelines.

ENG (electronystagmography): The ENG, combined with calorics (irrigating the ear with warm and then cold water), detects vestibular system dysfunction via measurements of nystagmus (constant, involuntary eye movement). ENG evaluation should also include a variety of eye-movement and eye-position subtests (e.g., saccades, gaze, tracking, and Dix-Hallpike).

VOR (vestibulo-ocular reflex): This reflex represents the neuronal connection between the semicircular canals in the peripheral vestibular system and the vestibular nuclei in the brainstem. A VOR evaluation assists in detecting peripheral vs. central vestibular-system damage; thus, determining the proper treatment and educational approaches.

VAT (vestibular autorotation test): The VAT is a 15-second, computerized test that monitors the vestibulo-ocular reflex during natural motion. Many evaluators now recommend the VAT instead of the ENG. The VAT provides physiological function information in two dimensions (the ENG provides information in only one dimension).

Other diagnostic tools used to measure neuronal dysfunction are those based on brainstem-evoked responses: BAER, BVER, and SSER. Evoked-response tests are helpful in assessing persons with possible auditory or vision problems or dizziness of central, rather than peripheral, origin. BAER is occasionally combined with the ENG and calorics to assess vestibular dysfunction, as well as some eye movement disorders, resulting from MTBI.

Polysomnography evaluates the pattern and type of sleep disturbance such as nocturnal seizures, sleep apnea (temporary cessation of breathing), or narcolepsy (recurrent, involuntary, daytime sleep). Determination of the specific, underlying causes helps direct the appropriate treatment.

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