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Autonomic function appears to be altered inconcussed patients; especially when aphysiological stressor is present. Heart ratevariability (HRV) during whole body exercise isattenuated in concussed patients compared tohealthy controls. However; HRV during isometrichandgrip exercise has been shown to have asimilar response between concussed patientsand healthy controls. The cold pressor test (CPT)is an exercise independent test that could beused to identify shifts in autonomic function inconcussed patients. We tested the hypothesisthat heart rate and the root mean squared ofsuccessive differences (representingparasympathetic control) during the CPT inconcussed patients is impaired versus healthycontrols. We found that parasympathetic controlof heart rate is not altered during the CPT inrecently concussed patient. However; the bluntedheart rate response does indicate that cardiacautonomic control is impaired in recentlyconcussed patients.

Heart Rate and Heart Rate Variability during the Cold Pressor Test in Recently Concussed PatientsMorgan C. O’Leary, James R. Sackett, Zachary J. Schlader, John J. Leddy, and Blair D. JohnsonDepartment of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, Department of Orthopedics, University at Buffalo, Buffalo, NY

Funding

Conclusions

Abstract

Background

• There is conflicting evidence that heart ratevariability (HRV) at rest is attenuated inconcussion patients.

• However, concussion patients have beenshown to have attenuated HRV during physicalstressors, such as hand grip exercise or wholebody exercise, versus healthy controls.

• Autonomic activation during exercise is relianton several peripheral feedback mechanisms,which could be impaired in concussionpatients.

• The cold pressor test (CPT) is widelyrecognized as a general sympathoexcitatorytest that could be easily used to assessautonomic function in concussed patients.

• It is currently not known if HRV during the CPTin concussion patients is attenuated versushealthy controls.

Purpose

We tested the hypothesis that heart rate and the rootmean squared of successive differences (RMSSD,which represents parasympathetic control) duringthe CPT in concussed patients is impaired versushealthy controls.

Methods

SubjectsConcussion Patients: 8 patients diagnosed with a concussion by a physician (4 women; age 20±1) were tested 5±1 days post injury.

Controls: 6 subjects (1 woman; age 25±4) weretested. These participants did not have had ahistory of suspected or confirmed concussion(s)within the last year.

Measurements• Heart rate (ECG)• Visual Analogue Scale (VAS)

Protocol• Subjects rested in the supine position for a 15minute baseline period.• Subjects then submerged their right hand up tothe wrist in an agitated ice/water slurry mixture(~1°C) for 120 seconds.

Data Analysis• Data were analyzed for R to R Interval (RRI),Heart Rate (HR), and RMSSD Using WinCPRSin 60-second increments at baseline, 60 secondsand 120 seconds into the CPT, and 60 secondspost CPT.• Values reported are mean ± standard deviation

• These preliminary data indicate that parasympathetic control of heart rate, represented by RMSSD, is notaltered during the CPT in recently concussed patients.• However, the blunted heart rate response during the CPT does indicate that cardiac autonomic control isimpaired in recently concussed patients.

University at Buffalo Center for Undergraduate Research and Creative ActivitiesUndergraduate Research Award

Symptom SymptomHeadache 4± 2 Difficulty remembering 2± 2"Pressure in head" 2± 2 Fatigue or low energy 4± 2Neck pain 1± 2 Confusion 2± 2Nausea or vomiting 1± 1 Drowsiness 3± 2Dizziness 2± 3 Trouble falling asleep 3± 2Blurred Vision 2± 3 More emotional 2± 2Balance problems 2± 3 Irritability 3± 2Sensitivity to light 3± 2 Sadness 2± 2Sensitivity to noise 2± 2 Nervous or anxious 2± 2Feeling slowed down 3± 2 Worse with physical activity? 87.5% yesFeeling like "in a fog" 3± 2 Worse with mental activity? 87.5% yes"Don't feel right" 4± 2 Worse with stress? 87.5% yesDifficulty concentrating 3± 2

Results

Baseline Symptom Severity

*Scale: none= 0, mild=1-2, moderate=3-4, severe=5-6

Visual Analogue Scale (VAS)

Values for symptom severity are from concussed patients only. Healthy subjects did not report any concussion symptoms

*

*

*

*

*Different from Baseline (P < 0.05).

Feel great, no

symptoms

Some symptoms

but tolerable

Symptoms a little worse

Symptoms much worse

Many symptoms

Feel bad, worst I

ever felt