Distinguishing sports-related SRC (SRC) from traumatic brain injury (TBI) in athletes having suffered acute head impact trauma has long been a challenge for sports health care providers. SRC and TBI, or injury resulting in intracranial hemorrhage (IH), cerebral swelling, or mid-line shift, can present with similar acute signs and symptoms. While proper management of both conditions is critical to the athlete’s health and well- being, failure to provide accurate acute differential diagnosis could result in unnecessary catastrophic outcomes. Elevated intracranial pressure (ICP) has been shown to result in specific sign and symptom patterns that may be useful in helping sports health care providers distinguish TBI from SRC (1), (2). Therefore, this paper will: 1) explain how TBI may result in elevated ICP, 2) discuss specific signs and symptoms that evolve as ICP rises, 3) explain how serial monitoring of specific signs and symptoms may be useful in identifying rising ICP, and 4) demonstrate a possible sideline assessment protocol using Sports Medicine Concepts’ Enhanced Vital Signs Assessment Tool.
Body’s Response to Rising ICP
The cranial compartment, vertebral canal, and dura form a rigid inelastic container that houses the brain, blood, and cerebral spinal fluid (CSF). ICP is the pressure inside the cranial compartment. Under normal conditions autoregulatory processes maintain pressure within the cranial compartment to within 1 mmHg (3). Rising ICP results from cerebral swelling or volume changes in the brain, CSF, or blood. In order to maintain ICP an increase in the volume of one of the cranial constituents must be offset by a compensatory decrease in volume of another. For example, an IH resulting in an increase blood volume within the cranial compartment is compensated for by elasticity properties of the brain and by displacement of CSF into spinal canal and ventricles within the brain. This compensatory mechanism allows for small increases in cranial volume that do not immediately result in elevated ICP (4), (3).
Signs and Symptoms of Rising ICP
Normal adult ICP is 7-15 mmHg (3). The body’s compensatory mechanism for controlling small increases in cranial compartment volume will accommodate pressures up to 25 mmHg. Therefore, initial increases in ICP may not result in any outward signs and symptoms that can be readily observed during acute sideline management. Mean arterial pressure (MAP) is the average pressure in an individual’s arteries during one cardiac cycle. The normal MAP range is between 65 and 100 mmHg. Cerebral perfusion pressure (CPP) is the pressure gradient between the systemic blood pressure and the pressure in the cranial compartment. The pressure difference is the gradient that is necessary to drive blood from the aorta into the cranial compartment. As ICP reaches MAP the pressure gradient required to drive blood from the aorta into the brain, or the CPP falls. The result of falling CPP is a decrease in cerebral blood flow (CBF). The decreased CBF triggers the body’s autoregulatory processes that increase systemic blood pressure (SBP) in an attempt to maintain adequate CBF. In the case of an IH, an increase in systemic blood pressure (BP) will facilitate bleeding into the cranial compartment leading to further elevation of ICP. The result is the initiation of a spiraling ICP-CPP-SBP cycle that will ultimately result in elevated ICP that leads to ischemia and brain infarction secondary to inadequate CBF (1), (2), (5).
As ICP exceeds the body’s compensatory mechanism an athlete is likely to begin exhibiting an increase in the number and severity of specific signs and symptoms. Signs and symptoms indicative of rising ICP may include headache, nausea, vomiting without nausea, ocular palsies, altered levels of consciousness, back pain, papilledema, and widened pulse pressure. In children, bradycardia may be particularly suggestive of high ICP (6). Specific signs and symptoms indicating the presence of an IH include bradycardia, hypotension, hypertension, respiratory depression, systemic vasoconstriction, altered mental status or lucid interval, hyperventilation, sluggish dilated pupils, and widened pulse pressure. Early recognition of these signs and symptoms is paramount to ensure that injured athletes receive medical treatment before ICP reaches 40-50 mmHg, at which point catastrophic outcomes secondary to brain infarction and brain death become more likely (7).
Catastrophic outcomes may also result secondary to a mid-line shift of the brain within the cranial compartment. A mid-line shift may result over time as IH results in a growing mass of blood that eventually pushes the brain from mid-line. If the mid-line shift results secondary to an IH, the on-set of signs and symptoms may develop over a time, depending on how long it takes for enough blood to collect in the cranial compartment to result in pushing the brain from mid-line. Signs and symptoms of a growing mass effect IH may include pupillary dilatation, abducens palsies, increased systemic blood pressure, bradycardia, irregular respiratory patterns, and a widen pulse pressure. Trauma may result in an immediate mid-line shift. If the mid-line shift is a direct result of trauma, dire signs and symptoms may present immediately. Regardless of a gradual or immediate on-set, a resulting mid-line shift will ultimately lead to brain herniation or brain stem compression resulting in brain infarction and decrease respiratory drive(8).
An injury resulting in rapid increases in ICP or mid-line shift will present with immediately life-threatening outward signs and symptoms indicating the need for immediate transport to an appropriate medical facility. Injury to the brain resulting in more gradual rises in ICP may initially mimic SRC. However, observation of certain sign and symptom trends could alert sports medicine professionals to the possibility of elevated ICP and the need for immediate transport. Vital signs trending is an assessment strategy that has been used to observe serial measures of heart rate (HR), respiration(R), blood pressure (BP), and temperature (T) at 10min intervals over a 30-minute period (9). In the following section the vital signs trending philosophy is modified and used to observe for the development of specific signs and symptoms indicative of rising ICP and the need for immediate transport of an injured athlete. Specifically, the traditional pre-hospital vital
signs trending protocol was changed from 10-minute to 5-minute serial measures to be more sensitive to the onset of subtle signs and symptoms.
Many of the subtle signs and symptoms of rising ICP or mid-line shift that present themselves during sideline assessment may be readily observed by trending three specific assessment batteries; the Sport Concussion Assessment Tool (SCAT) Symptoms Severity Score (10), the Sports Medicine Concepts’ Cranial Nerve Assessment Survey (See Appendix A), and Cushing’s Triad, which compares heart rate, respiration, and pulse pressure. Therefore, these traditional indicators of SRC and elevated ICP were added to the vital signs trending protocol. A theoretical application of this trending approach is explained in detail below followed by Sports Medicine Concepts’ Enhanced Vital Signs Assessment Tool that offers a means of efficiently applying this concept during sideline management.
Symptom Severity Graph
Typical sideline assessment using the SCAT form includes assessment of 22 signs and symptoms for which athletes are instructed to rate their symptom severity at the time of evaluation. Athletes are given a severity score ranging from 0 points, if they are not experiencing the sign or symptom at all, to 6 points, indicating the sign or symptom is severe. The total number of signs and symptoms out of a possible 22 is placed on the ICP Symptom Score Trending Graph (See Figure 1). The symptom severity score is calculated by adding up the severity rating numbers. This number is plotted on the Symptom Severity Trending Graph (See Figure 2). If this process were repeated at 5-minute intervals for a total of 30-minutes, general trends indicating the possibility of rising ICP may become evident. Generally, athletes who may have sustained a head injury resulting in IH may present with an increasing number of signs and symptoms or an increasing symptom severity rating. A rapid rise in symptoms or symptom severity scores during any interval in trending period may be indicative of rising ICP and the need to transport an athlete prior to the completion of the 30-minute trending period, particularly if the signs and symptoms involved include headache, nausea, or vomiting in the absence of nausea. Figures 1 and 2 illustrate a theoretical model of general trends in the number and severity of signs and symptoms that might be indicative rising ICP due to IH.
Another significant sign of IH that may be observed using the Symptom Score and Symptom Severity Trending Graphs is a lucid interval. A lucid interval is a period of time during which an athlete reports improvement in signs and symptoms followed by worsening signs and symptoms, including altered mental status (AMS). Figures 1 and 2 depict potential graphic representations of a lucid interval by illustrating a general trend of improvement followed by worsening severity scores.
Figure 1. Symptom Score indicating a possible hematoma
Figure 2. Symptom Severity Score trend indicating a possible hematoma
Cranial Nerve Assessment Graph
Although there is some overlap in the cranial nerve assessment survey with theSCAT Symptom Evaluation Form, specific assessment of all 12 cranial nerves is warrantedbecause any rise in ICP could have immediate impact on any of the cranial nerves due to their anatomical location at the base of the brain within the cranial compartment. Therefore, assess both motor and sensory function for all 12 cranial nerves using SMC’s Cranial Nerve Assessment Survey provided in Appendix A. Calculate the total number of abnormal findings out of a possible 12 and place this number on the Cranial Nerve Trending Graph shown in Figure 3. Repeat this assessment at 5-minute intervals for a total of 30 minutes. A general trend indicating a rise in the number of abnormal findings may indicate the presence of rising ICP due to IH, and the need for immediate transport of the injured athlete. More specifically, rising ICP has been shown to result in ocular palsies, papilledema, pupillary dilatation, and abducens palsies. These specific conditions may present themselves upon assessment of the Optic (II), Oculomotor (III), Trochlear (IV), and Abducens (VI) nerves.
Cushing’s Triad is an assessment battery that compares pulse pressure, heart rate, and breathing patterns to indicate the presence of intracranial hemorrhage or edema. Pulse pressure, or the amount of pressure required to create the feeling of a pulse, is the mathematical difference between the systolic and diastolic pressure. For example, normal blood pressure is 120mmHg (systolic) / 80mmHg (diastolic), resulting in an normal healthy pulse pressure of P (systolic) – P (diastolic) = 40 mmHg. The normal resting pulse pressure of a healthy individual, sitting position, is about 40-80 mmHg (11). Pulse pressure, heart rate, and respiration rate will increase with exercise, but have all shown to trend towards normal within 10-minutes following the cessation of exercise. Therefore, an injured athlete presenting with an elevated pulse pressure, heart rate, or respiration rate should be trending towards normal within 10-minutes, and should certainly demonstrate a normal pulse pressure, heart rate, and respirations following a 30-minute trending period.
Figure 3. Cranial Nerve Trending Graph indicating a potential hematoma
To assess Cushing’s Triad, use a blood pressure monitor to measure blood pressure and heart rate. Additionally, assess the athlete’s respirations and respiration rate. Calculate pulse pressure and place the pulse pressure, heart rate, and respiration rate values on the Cushing’s Triad Trending Graph shown in Tables 4. Blood pressure of a normal healthy individual should trend toward 120mmHg (systolic) / 80mmHg (diastolic) resulting in a normal pulse pressure of 40-80mmHg. Respiration rates should trend toward 10-12 breaths per minute. A more sensitive measure of effective respiration may be obtained by using a simple finger pulse oximeter to measure blood oxygen saturation (SpO2). Normal range for SpO2 is typically considered from 95%-99%, but SpO2 may be lower for individuals in high altitude environments (12). A general trend indicating an elevated pulse pressure combined with bradycardia and ineffective respirations might indicate the presence of IH or edema and the need for immediate transport of the injured athlete. Incidentally, a low pulse pressure may also be problematic, indicating the presence of shock or significant
blood loss. A pulse pressure is considered low if it is less than 25% of the systolic value(11).
Figure 4. Cushing’s Triad indicating elevated pulse pressure, bradycardia, and erratic respirations.
SMC Enhanced Vital Signs Assessment Tool
The intent of the prior discussion was to graphically demonstrate how sign and symptom trends indicative of rising ICP secondary to IH may present. The SMC Enhanced Vital Signs Trending Assessment Tool is intended to offer sports medicine professionals a mechanism for applying vital signs trending concept during on-field assessment of a potentially head injured athlete.
When the signs and symptoms indicating the need for immediate transport to an emergency department have been ruled out, but the potential for the athlete’s condition to deteriorate remains or when vital sign measures are abnormal, begin recording information on the SMC Enhanced Vital Signs Trending Assessment Tool at 5-minute intervals for 30-minutes. Clinical signs and symptoms that fail to normalize following the 30 min trending period or that worsen significantly during any interval during the trending period may be indicative of rising ICP pressure secondary to TBI.
Total Number of SCAT Symptoms and Symptom Severity Score
Using the SCAT Symptom Evaluation chart calculate the total number of SRC-like symptoms and the corresponding Symptom Severity Score. A significant increase in the number of SRC-like symptoms or the symptom severity score may indicate the need to transport the athlete to the nearest Level 1 trauma center.
Altered Mental Status
Using the Glasgow Coma Scale assess the athlete for any variations in level of consciousness or the presence of a lucid interval.
Using the Sports Medicine Concepts, Inc., Cranial Nerve Assessment Survey record the number of abnormal clinical findings (out of a possible 12). An increase in the number of abnormal clinical findings during any interval or remaining abnormal findings following the 30-minute trending period may be indicative of the need to transport the athlete from the field to the nearest Level 1 trauma center.
Heart Rate, Blood Pressure, and Pulse-Pressure
Use an appropriate heart rate / blood pressure monitor to record the athlete’s heart rate, blood pressure, and pulse pressure (Systolic-Diastolic) readings. Persistent heart elevation above 100 bpm, hypotension, hypertension, and pulse-pressures above 100 mmHg could be indicative of rising intra-cranial pressure, and the need to transport the athlete by EMS to the nearest Level 1 trauma center.
Blood Oxygen Saturation
Using a pulse-oximeter take serial measures of the athlete’s blood oxygen levels. Abnormal blood oxygen levels may be indicative of the need to transport the athlete by EMS to the nearest Level 1 trauma center.
Figure 5. SMC’s Enhanced Vital Signs Trending Assessment Tool
Assessing pulse pressure, heart rate, respirations, abnormal cranial nerve finding, and signs and symptoms of SRC at 5 minutes intervals for a period of 30 minutes may provide sports medicine providers with a mechanism for sideline identification of head injuries that are greater risk of TBI, resulting in a need to immediately transport the injured athlete to an appropriate medical facility. It is important to note that vital signs trending as a sideline assessment tool is not without significant limitations. The presence of any of the signs and symptom patterns discussed in this article may suggest an increased potential for TBI, but their absence does not rule out the possibility that a TBI exists. Additionally, the trending graph results presented here represent only one example of sign and symptom patterns that result in a graphic form that may indicate the presence of a TBI. Other trending patterns may produce other graphic forms also indicative of a TBI. Therefore, sports medicine providers should consider this sideline evaluation protocol only as part of a comprehensive head injury management plan that includes a multi-disciplined emergency action plan. Future research efforts should focus on the validity and reliability of the ICP Trending Graphs and the SMC Enhanced Vital Signs Trending Assessment Tool as predictors of TBI resulting from head impact trauma in sports.
1. Orlando Regional Healthcare, Education and Development. Orlando Regional Health Care. [Online] 2004. [Cited: April 27, 2012.]
2. S., Dawodu. Traumatic brain injury: definition, epidemiology, pathophysiology.emedicine.com. [Online] 2005. [Cited: April 27, 2012.]
3. Steiner LA, Andrews PJ. Monitoring the injured brain: ICP and CBF. British Journalof Anaesthesia. 2006, Vol. 97, 1, pp. 26-38.
4. B, Mokri. The Monro-Kellie hypothesis in CSF volume depletion. Neurology. June 2001, Vol. 56, 12, pp. 1746-8.
6. K, Sanders MJ and McKenna. Head and facial trauma. [book auth.] Mosby. Mosby’s paramedic textbook. 2nd revised Ed. s.l. : Mosby, 2001, 22.
7. A, Singh J and Stock. Head Trauma. emedicine.com. [Online] 2006. [Cited: April 27, 2012.] http://www.emedicine.com/ped/topic929.htm.
8. A, Downie. Tutorial: CT in head trauma. http://www.radiology.co.uk. [Online] 2001. [Cited: April 27, 2012.] http://www.radiology.co.uk/srs-x/tutors/cttrauma/tutor.htm.
9. Hart JM, Potter B, Sibold J. Vital Signs Trending and the Rule of 100s. Jul 2012, Vol.4, 4, p. 152.
10. McCrory P, Meeuwisse W, Johnston K, Dvorak J, Aubry M, Molloy M, & Cantu R. Consensus statement on SRC in sport: the 3rd international conference in sport help in Zurich, November 2008.Journal of Athletic Training. 2009, Vol. 44, 4, pp. 434-448.
11. High Blood Pressure. highbloodpressure.com. [Online] [Cited: April 27, 2012.]
12. ChoiceMMed. OxyWatch Quick Operation Guide. Bristol, PA : ChoiceMMed America Co., 2013.
13. J, Ghajar. Traumatic brain injury. Lancet. September 2000, Vol. 356, 9233, pp. 923-9.