Zhangjie Su

The effect of persistent post-concussive symptoms on cognitive performance after sport concussion

Objective We aim to study the effect of persistent post-concussive symptoms on cognitive performance of elite athletes, based on the hypothesis that persistent symptoms could impair athletes’ cognitive performances and functional outcomes. Design Prospective observational and longitudinal case control study. Setting University research centre, single centre. Participants 7 athletes with persistent symptoms (>2 weeks, assessed at median 31 days post-concussion), 10 athletes with brief symptoms (<3 days, assessed within a week, median 3.5 days), and 9 age-matched healthy volunteers. Inclusion criteria: male/female athletes (aged 18–40) in contact sports who sustained concussion(s) recently, being symptomatic with normal neuro-radiological findings at enrolment. Intervention Independent variables: post-concussive symptom scores and duration of symptoms. Outcome measures Multi-dimensional scores from Sport Concussion Assessment Tool III, Immediate Post-concussion Assessment and Cognitive Testing, WAIS symbol search and digit span backward tests. Main results Patients with persistent symptoms scored less in the symbol search test than those with brief symptoms and the healthy volunteers (grouping effect p=0.006; post hoc tests p=0.039 and 0.004, respectively). In all 17 patients, symptom scores correlated with reaction time (ρ=−0.61, p=0.009), and visual motor speed correlated with symbol search scores (ρ=0.59, p=0.013). 6 patients who completed follow-up assessments when symptom-free showed improvement in their symbol search scores (p=0.042) and visual memory (p=0.028). Conclusions Concussed athletes with persistent symptoms performed poorly in visual perception/analysis and information processing. Persistent post-concussive symptoms could affect athletes’ visual memory, perception/analysis, reaction time and information processing speed, thus precipitating them to further injuries should they return to play prematurely. Competing interests None.

Disability from posttraumatic headache is compounded by coexisting posttraumatic stress disorder

Background Posttraumatic headache (PTH) occurs in up to 82% of patients with traumatic brain injury (TBI). Posttraumatic stress disorder (PTSD) occurs in 39% of those with PTH. This study evaluates whether PTSD affects PTH disability. Methods Eighty-six patients with TBI were prospectively evaluated in a secondary care trauma center. Headache disability was assessed using the Headache Impact Test version 6 and signs indicative of PTSD using the PTSD Check List Civilian version. Results Increased PTSD-type symptoms were significantly associated with increased headache disability (p<0.001), as were employment status and loss of consciousness (p=0.049 and 0.016, respectively). Age was negatively correlated with headache disability (Spearman’s correlation rho=0.361, p=0.001). Conclusion Increased severity of PTSD-type symptoms is significantly associated with increased headache disability in patients with chronic PTH. Managing PTSD symptoms in patients with chronic PTH may facilitate headache management.

Comparison of near infrared spectroscopy with functional MRI for detection of physiological changes in the brain independent of superficial tissue

Abstract Background A reliable portable non-invasive monitor for use in brain injury is needed, so near infrared spectroscopy (NIRS) has potential. Historical inconsistencies in NIRS have prevented its use, often attributed to the contamination of signal from extracranial tissue. We aimed to validate the brain signal from frequency domain NIRS (advanced NIRS technique), comparing its abilities with functional MRI (fMRI) to isolate physiological activity in the brain from those of extracranial tissue. Methods In a prospective healthy volunteer study, nine individuals (six male, three female, age range 21–40 years) performed supine Valsalva manoeuvres (adequacy monitored via finger photoplethysmography and capnography). The Valsalva manoeuvre provided a suitable model for cerebral ischaemia and rises in intracranial pressure. During the manoeuvre, a portable frequency domain NIRS device was targeted separately at the brain and at extracranial tissue, and fMRI (blood oxygen load dependent sequence) was taken from regions corresponding to both fields of NIRS acquisition. Area under the curve analysis of the change in variables during the Valsalva manoeuvre was analysed by the Wilcoxon rank sum method with multiple pairwise comparisons between the brain and extracranial tissue signals for both NIRS and fMRI. Findings We observed similar responses in both brain and extracranial tissue: in all volunteers, oxygenation in brain tissue during the Valsalva manoeuvre decreased (mean −7·2% NIRS [SD 4·7], −3·4% fMRI [SD 1·46]) and oxygenation from the extracranial acquired data increased (mean +6·1% NIRS [SD 2·72], +4·4% fMRI [SD 3·45]), matching physiological predictions. These brain and extracranial signals were significantly different in both fMRI and NIRS (p=0·00025 and 0·00115, respectively). Interpretation Our findings confirm that frequency domain NIRS can detect specific changes within the brain tissue during the Valsalva manoeuvre independent of physiological features of extracranial tissue and reflects changes observed by fMRI. Therefore, the frank changes in the brain observed by frequency domain NIRS are brain specific, demonstrating the potential for this method to be used within the context of brain injury. Funding National Institute for Health Research Surgical Reconstruction and Microbiology Research Centre.

DISABILITY FROM POST-TRAUMATIC HEADACHE IS COMPOUNDED BY PTSD

Background Post-traumatic headache (PTH) occurs in up to 82% of patients with traumatic brain injury (TBI). Post-traumatic stress disorder (PTSD) occurs in 39% of those with TBI. This study evaluates whether PTSD affects PTH disability. Methods 151 consecutive patients with TBI were evaluated from a secondary care trauma centre. Headache disability was assessed using the Headache Impact Test version 6 (HIT 6) and PTSD using PTSD Check List Civilian version (PCL-C). Results In patients with chronic PTH, increased PTSD symptoms were significantly associated with increased headache disability (p<0.001), as were employment status and loss of consciousness (p=0.049 and 0.016, respectively). Age was negatively correlated with headache disability (Spearmans correlation −0.361, p=0.001). Conclusion Increased PTSD severity is significantly associated with increased headache disability in patients with chronic PTH. Managing PTSD in patients with chronic PTH may facilitate headache management.

Monitoring the Injured Brain - High density near infrared probes and registered atlas models improve cerebral saturation recovery

High density near infrared probes and registered subject specific head models are used to show the potential improvements to the quantitative accuracy of recovered parameters relevant to monitoring an injured brain.

Do we forget to treat concussion

Although the absolute definition is often debated, concussion can be defined as a temporary disruption in normal brain function after a mechanical impact or transmission of force through cerebral tissue. A frequent misconception in the diagnosis is that an individual must have ‘lost consciousness’ to have become concussed; this is not the case. A temporary loss of function may be manifested as blurring of vision, confusion or unsteadiness.

Monitoring the injured brain: registered, patient specific atlas models to improve accuracy of recovered brain saturation values

The subject of superficial contamination and signal origins remains a widely debated topic in the field of Near Infrared Spectroscopy (NIRS), yet the concept of using the technology to monitor an injured brain, in a clinical setting, poses additional challenges concerning the quantitative accuracy of recovered parameters. Using high density diffuse optical tomography probes, quantitatively accurate parameters from different layers (skin, bone and brain) can be recovered from subject specific reconstruction models. This study assesses the use of registered atlas models for situations where subject specific models are not available. Data simulated from subject specific models were reconstructed using the 8 registered atlas models implementing a regional (layered) parameter recovery in NIRFAST. A 3-region recovery based on the atlas model yielded recovered brain saturation values which were accurate to within 4.6% (percentage error) of the simulated values, validating the technique. The recovered saturations in the superficial regions were not quantitatively accurate. These findings highlight differences in superficial (skin and bone) layer thickness between the subject and atlas models. This layer thickness mismatch was propagated through the reconstruction process decreasing the parameter accuracy.

Comparison of neurological NIRS signals during standing Valsalva maneuvers, pre and post vasoconstrictor injection

Near infrared spectroscopy (NIRS) has potential to offer a fast and non-invasive method of assessing cerebral saturation in a clinical setting, however, there are concerns that NIRS brain measures suffer contamination from superficial tissues. This study used the Valsalva manoeuver (VM) to determine whether NIRS could differentiate between superficial (from somatic tissue) and neurological changes in the context of traumatic brain injury. A potent vasopressor was used to assess the effect of reducing total haemoglobin concentration in the superficial regions of the forehead. Frequency domain NIRS measurements during the VM pre and post vasoconstrictor injection, combined with simulation data, conclusively show that NIRS can detect neurological changes, in both haemoglobin content and saturation, when positioned on the forehead. The effect of superficial contamination in this instance appeared to be insignificant, with no statistically significant change in saturation over 8 patients, even with a drop in superficial haemoglobin concentration due to the vasoconstrictor, confirmed by laser Doppler. Nevertheless, simulations indicated that the absolute values of the recovered NIRS parameters are not quantitatively accurate; however a direct comparison with invasive measures is needed to confirm this.