The Effect of Cryotherapy on Cerebral Hemodynamics Within Healthy Subjects
Condition: Cryotherapy Effect; Oxygen Deficiency
MeSH terms: Hypoxia
Study type: Interventional
Phase: Phase 1

Summary: 
      Upon suffering a concussion, a neurometabolic cascade including an increase in glucose and
      oxygen demand occurs for up to 48 hours post-insult.5 This period of increased glucose and
      oxygen demand is coupled with a period of hyperperfusion and decreased cerebral blood flow.
      6-9 Cryotherapy in the musculoskeletal system has been shown to decrease tissue temperature,
      blood flow, oxygen and metabolic demands.10-17 Cryotherapy following moderate or severe
      traumatic brain injury has been demonstrated to decrease intracranial metabolic processes and
      oxygenation consumption.18-23 Although the benefits of cryotherapy have been established in
      moderate-severe TBI, the effects of superficial cranial cooling in individuals with and
      without concussion are unknown. The purpose of this randomized control trial is to evaluate
      the effects of superficial cryotherapy on cerebral blood flow and cognitive function in
      healthy, recreationally active young adults.
    

Detailed description: 
      The prevalence of concussion has been estimated to be between 4,380 and 10,403 concussions
      per day in the United States annually with over an estimated 3 million visits to emergency
      departments each year.1 Symptoms following a concussion last up to 10 days for 90% of cases2;
      however, the reduction of symptoms in this time frame does not indicate full neurometabolic
      recovery.

      Following concussion, a neurometabolic cascade of events immediately occurs following initial
      impact with return to normative values around 30 days post-injury. In an attempt to maintain
      homeostasis in the brain following impact, glucose and oxygen demand increases temporarily
      and are coupled with periods of increased hyperperfusion and decreased cerebral blood flow
      (CBF). Although the neurometabolic timeline immediately following impact is only generally
      understood, there is consensus upon acute increases in CBF and metabolic activity followed by
      decreased CBF until return to normative values.

      Cryotherapy has been studied extensively for its' effects throughout the musculoskeletal
      system. Cryotherapy in the musculoskeletal system has been shown to decrease tissue
      temperature and blood flow, as well as decrease oxygen and energy demands.12-19 Cryotherapy
      has also been applied in cases of moderate or severe traumatic brain injury and has
      demonstrated to decrease intracranial metabolic processes and oxygenation consumption.
      Although the potential benefits of cryotherapy have been established in cases of moderate to
      severe traumatic brain injury (TBI), there is no current research examining cryotherapy in
      the treatment of concussion.

      A convenience sample of 34 healthy, recreationally active individuals between the ages of
      18-25 years will be recruited for participation in this study. The independent variable in
      this study will be group (cryotherapy, control). The primary outcome measures of interest are
      cognitive functioning measured using the Stroop Test and cerebral blood hemodynamics and
      hemoglobin saturation measured using near infrared spectroscopy. The pain visual analog scale
      (VAS) will be used to quantify tolerance to the intervention.

      The following study will address the following objectives and related hypotheses:

      Objective 1: To determine if the application of cryotherapy influences intracranial
      hemodynamics within healthy recreationally active young adults.

      Hypothesis 1: Cryotherapy will cause a decrease in intracranial hemodynamics; specifically,
      the CO2 saturation and deoxygenated hemoglobin causing a decrease in intracranial metabolic
      activity.

      Objective 2: To determine if the application of cryotherapy decreases cerebral blood flow
      within healthy recreationally active individuals.

      Hypothesis 2: The application of cryotherapy will not cause a change in cerebral blood flow
      due to the highly regulated central nervous system.
    

Intervention name(s): CryoHelmet
Intervention type(s): Device
Intervention description(s): Cryotherapy was administered using the Catalyst CryoHelmet™ (All-Star Sporting Goods®, Shirley, Massachusetts, USA). The CyroHelmet is a flexible helmet equipped with gel ice packs meant to cool the head and neck.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Thirty-four healthy participants were recruited from a large urban university. Participants were included if they were healthy and between the age of 18 and 25 years old. After obtaining consent, participants completed symptom, mood and medical history inventories. After determining if a participant met inclusion criteria, the subject remained seated at a testing station for a 10-minute rest period prior to NIRS data collection. Randomization was performed a priori using a random number generator and was stratified on sex. Participants either received superficial cryotherapy or sat quietly for 20 minutes.
Masking: Single (Investigator)
Primary purpose: Treatment