Measure of Cerebrovascular Dysfunction After TBI With fNIRS

The prospective study design will consist of two study groups; the experimental group and the control group. In the Experimental Group (Group 1) we will enroll adult participants with TBI with persistent post-concussion symptoms or abnormalities on neuropsychological testing. In Group 2 we will enroll adult participants to serve as age and gender-matched healthy controls. Our goal is to recruit 100 subjects total in two groups of age and gender matched subjects, as follows: TBI (n = 50) and non-TBI (n = 50).

Participants in both groups will undergo NIRS testing with hypercapnia challenge, to measure the increase in hemodynamic flow signal during hypercapnia challenge via 2 methods, the breath holding and the Douglas bag methods. We will test intersessional validity of the NIRS-hypercapnia challenge in the first 20 (10 TBI and 10 non-TBI) subjects who are willing to return for a second visit of repeat testing.

The NIRS system is composed of 4 light sources and 10 detectors with a 16 point configuration system applied on the forehead of the subject. In our experiment, light intensity collected at each detector will be transformed into a signal related to the local concentrations of oxy- and de-oxyhemoglobin during the challenge. Each experiment will give a set of subject data, consisting of the peak amplitude and time-to-peak of the hemodynamic signals measured.

Inclusion criteria

• ALL participants (TBI and non-TBI) subjects Males and females, ages 18 to 60 years, inclusive Able to read, write, speak and understand English
• A history of TBI
• Persistent post-concussive symptoms, according to the DSM-IV Research
• Criteria for Post-Concussional Disorder, including:

• Evidence from neuropsychological testing of difficulty in attention or memory. (refers to neuropsychological testing done as a part of the patient's hospital or rehabilitation care not as a part of screening for this study)
• Three or more of the following symptoms, which started shortly after the trauma and persist for at least three months:

• Fatigability
• Disordered sleep
• Headache
• Vertigo or dizziness
• Irritability or aggression
• Anxiety, depression, or affective instability
• Changes in personality (e.g. social or sexual inappropriateness)
• Apathy or lack of spontaneity

Symptoms in criteria (a) and (b) must have their onset after trauma, or there was a significant worsening of pre-existing symptoms after trauma.

Exclusion criteria

• History or evidence of pre-existing neurological or psychiatric disorder not related to TBI, such as:

• Multiple sclerosis, pre- or co-existing
• Stroke (other than stroke at the time of TBI)
• Pre-existing developmental disorder
• Pre-existing epilepsy
• Pre-existing major depressive disorder
• Pre-existing schizophrenia
• Known allergy to latex (used in the NIRS apparatus band applied to the forehead)