JEMS Clinical Review Features
This clinical review feature article is presented in conjunction with the Department of Emergency Medicine Education at the University of Texas Southwestern Medical Center, Dallas.
>>Review the anatomy and physiology of the central and peripheral
>>Identify the components of a neurological examination.
>>Discuss and apply an appropriate neurological assessment based upon a given patient_s presentation, mechanism of injury and/or
Afferent nerve:A nerve that carries sensory impulses from receptors to the central nervous system.
Aphasia:Partial or total loss of the ability to articulate or understand spoken or written language.
Decerebrate posturing:Abnormal body posture involving rigid extension of the arms and legs, usually associated with a lower brain injury.
Dermatome:An area of skin in which sensory nerves all come from a single spinal nerve root.
Efferent nerve:A nerve that carries motor impulses from the central nervous system to the periphery of the body.
Meninges:Three layers of membranes that surround the brain and spinal cord.
Neuron:The main functional unit of the nervous system.
Transient ischemic attack (TIA):A neurological disorder occurring when a patient temporarily exhibits the signs and symptoms of a stroke.
Anatomy & Physiology
The nervous system includes a complex array of components and functions that interact in a wide variety of ways on a daily basis. It_s functionally and structurally separated into the central and peripheral nervous systems. The brain and spinal cord comprise the central nervous system (CNS) and the peripheral nerves constitute the peripheral nervous system (PNS).
There are two subdivisions of the PNSƒthe somatic nervous system and autonomic nervous system. The somatic nervous system is under conscious control. In contrast, the autonomic nervous system regulates activities that aren_t under conscious control. Pupillary size, blood vessel diameter and heart rate are a few of the activities regulated by the autonomic nervous system. The autonomic nervous system is further subdivided into the sympathetic ("fight or flight") and parasympathetic ("feed or breed") nervous systems. These two systems work in direct opposition to maintain homeostasis.
At the cellular level is the main functional unit of the nervous systemƒtheneuron. Any disruption in the structure or function of neurons can lead to a negative condition. Structural disruption could occur from a stroke, leading to damaged and dead neurons. Improper function can result because of electrolyte imbalances, such as hyponatremia.
The structure of nerves (tracts in the CNS) is relatively complex, with each possessing multiple components. There are 32 pairs of nerves in the peripheral nervous system and 12 pairs of cranial nerves. They can be classified into sensory (afferent), motor (efferent) or mixed. Sensory nerves receive information from the body and deliver the message to the spinal cord, which is the pathway to the brain. Motor nerves extend to their target organs, such as muscle tissue or glands. Mixed nerves gather information and cause actions.
The crown jewel of the nervous system is the brain, with its amazing ability to think, interpret stimuli and regulate thousands of functions. Here we find billions of neurons and synaptic connections working in concert to control the entire body. This gray-colored gelatinous mass is more complex than the world_s most sophisticated computer, but it weighs only 1,400 grams in the average adult. The outermost layer of the brain is the cerebral cortex, which has a gray appearance. The inner white area is the subcortex.
Various sulci and gyri give the brain its unique ridged appearance.
The brain is categorized into regionsƒthe cerebrum, cerebellum and brainstem. To help identify structures and functions, the cerebrum is categorized into lobesƒfrontal, temporal, parietal and occipital. Each lobe has a specific function, although they share responsibilities. The frontal lobe can reason, plan and problem-solve, whereas the parietal lobes are associated with movement, orientation and perception of stimuli. Recognition of auditory stimuli occurs in the temporal lobes. In contrast, visual stimuli are interpreted in the occipital lobe. This list is not exhaustive, but knowledge of the main functions of each area can help to localize where an injury or dysfunction is located.
The brainstem, common to all animals, controls such vegetative functions as respiration, heart rate and blood pressure. Like the cerebrum, the brainstem is subdividedƒthe pons, medulla oblongata and midbrain. The brainstem lies atop the highest portion of the spinal cord. Most of the 12 pairs of cranial nerves extend off the brainstem.
Superior and posterior to the brainstem is the cerebellum, which fine-tunes muscular movements into smoothly coordinated motions. Inferior to the brainstem lies the body_s main neural conduit, the spinal cord. This amazing structure serves as the pathway for all nervous system impulses going to and from the body. It extends from the base of the brain down to approximately the first lumbar vertebrae. Thirty-two pairs of spinal nerves extend from the spinal cord out to the rest of the body.
Given the central nervous system_s important function, it makes sense that the brain and spinal cord are so well-protected. A rigid, yet lightweight skull provides an armor-like defense against direct contact with external stimuli. The spinal cord is protected by a collection of 33 bones arranged in an S-shaped curve. There_s also a three-layered cloth-like covering, known as themeninges, which covers the brain and spinal cord. It provides added protection and support. The dura mater lies on the outermost surface and is a tough, inelastic layer. Under the dura mater lies the arachnoid membrane, a more delicate structure that resembles a spider_s web. The pia mater lies adjacent to the brain and spinal cord.
Now that we_ve refreshed your knowledge of related anatomy and physiology, let_s apply it to common scenarios and consider how each indicates a neurological exam.
Case #1: Confusion
EMS is dispatched to the home of a 66-year-old male, whose wife called 9-1-1. On arrival, the wife relates that the patient suddenly began acting "confused" and called a pencil a penguin. The patient has a history of hypertension and atrial fibrillation for which he takes prescribed medication. Vital signs are pulse 102, respirations 20, BP 188/90 and pulse oximetry 98%. He_s not a diabetic, and the blood glucose reading is 82 mg/dL. He has a history of atransient ischemic attack (TIA)occurring three months prior to this event.
Given the history provided by the wife, the patient is experiencing a neurological deficit that hasn_t yet been assessed. The paramedic suspects a stroke is present and begins a neurological assessment. Using the Cincinnati Prehospital Stroke Scale (CPSS), the paramedic asks the patient to repeat a simple sentence. There_s no slurring, but the patient repeats words that are different than what the paramedic stated. Assessment for facial droop reveals a right-sided deficit, although the family initially reported that the left side appeared abnormal. Next, the patient is asked to raise his arms upward at a 90_ angle, close his eyes and hold the position for five seconds. During this test, the patient_s right arm drifts down toward his body. The entire exam takes less than a minute to complete. With enough information for the EMS crew to declare a stroke alert, the patient is quickly moved to the ambulance.
While en route to the hospital, additional assessment is performed to further measure the level of deficit. Using the Miami Emergency Neurological Deficit (MEND) exam, the field providers ask the patient to repeat the phrase, "You can_t teach an old dog new tricks." As with the initial on-scene assessment, the patient continues to recite different words. Next, they begin to assess the patient_s ability to recall his age and the month. The patient says the word "Friday" when asked both questions and appears frustrated. He_s then asked to close his eyes and open them and is able to do both on command. Facial droop is reassessed with no change.
The next step is to assess the visual fields. The EMT places both hands equidistantly apart and spaces them approximately the width of the patient_s shoulders. Both hands are held approximately six to 12 inches away from the patient at approximately head level for the top two visual fields. Because of the language problem and right-sided weakness, the patient is asked to point at any movement with his left hand. Each of the EMT_s hands are moved, but the patient detects movement only on the left. The same procedure is repeated for the lower visual fields, with the EMT_s hands positioned at approximately shoulder level. Movement is detected on the left again but not on the right. The EMS crew continues the exam, asking the patient to hold his head still while tracking the side-to-side motion of the paramedic_s finger with his eyes only. The patient is able to move his eyes to the center, but they drift back to the left when the finger is moved to the patient_s right.
Assessment of the upper extremities includes assessment of motor and sensation. The patient is again asked to raise his arms until they are fully extended at the chest level. He_s asked to close his eyes, and the crew again witnesses the right arm drifting downward. The patient is asked to keep his eyes closed while sensation is assessed. Knowing that the patient isn_t communicating well verbally, the paramedic asks the patient to raise the hand that_s being touched. A gentle brushing motion against the skin of the patient_s left hand is quickly detected. The same assessment performed on the right elicits no response. When both sides are assessed, the patient only raises his left hand.
Coordination of the upper extremities is assessed next by asking the patient to reach out and touch an extended finger to the paramedic_s finger, which is positioned a full arm_s length away. The patient is then directed to touch his nose in a smooth motion with the same finger and return it to the paramedic_s finger. No dyscoordination is discovered. Assessment of the right upper extremity is attempted, but weakness prevents the assessment from being performed.
A similar motor-strength assessment is performed on the patient_s lower extremities. For this test, the patient doesn_t need to close his eyes. He_s asked to raise each leg approximately 12 inches off the stretcher. The left leg rises without difficulty, but the right doesn_t rise at all. Sensation is assessed using the same technique outlined for the upper extremities with a sensory deficit noted on the right. Coordination is assessed by asking the patient to lift his left leg, touch his left heel to the right knee, and slide the foot down in one motion. No deficit is discovered on the left. Although the assessment was attempted on the right, weakness prevented the patient from performing the motion.
The EMS crew was tipped off to the possibility of a stroke from the wife_s report of confusion along with the history of hypertension, atrial fibrillation and prior TIA. When presented with findings that suggest stroke, EMS providers should use the quick and efficient CPSS exam. Discovering deficits suggesting stroke, such as facial droop, speech abnormalities or arm drift, should prompt rapid transport with interventions and further assessments performed en route.
In this case, the crew also performed the MEND exam to provide additional information to the emergency department (ED) staff. This particular neurological assessment is derived from elements found in the National Institutes of Health Stroke Scale (NIHSS), a more comprehensive exam that_s conducted at the hospital. The MEND exam can be taught to prehospital providers in such a manner that enables the student to detect stroke and define its overall location at the conclusion of the course. By using features directly from the hospital assessment, a more accurate comparison from field assessment to hospital assessment is possible. In other words, we can compare apples to apples. If the field providers simply assessed grip strength and pupils, there would be no direct correlation to the hospital exam.
Exam findings for this patient strongly correlate to a left hemisphere stroke, which includes right-sided weakness, left gaze preference andaphasia. The initial report of confusion was not accurate from a medical assessment standpoint. If the patient were in fact confused, he wouldn_t have been able to follow all the commands outlined in the case. This is an important point for the savvy EMS provider to note. A patient with expressive aphasia is not necessarily confused but has a dysfunction in the brain that prevents normal verbal or written communication.
Case #2:Fall Injury
An ambulance is dispatched to a commercial building for a fall injury. On arrival, the EMS crew is met by a frantic employee of a shipping warehouse. The man reports that a co-worker fell off a ladder and was unconscious for at least two minutes. The crew rushes to the patient_s side and observes a 24-foot extension ladder propped against the building near the injured man. The patient is approximately 24 years old and is fully lucid when the crew reaches his side. His primary complaint is head pain.
While one EMT begins conducting the initial assessment, the paramedic assesses the height of the fall, surface struck and body part first impacted. It_s determined that the patient struck his head on the concrete first, but from an oblique angle. The initial assessment reveals a patent airway, rapid respirations, a rapid pulse and an alert patient. A non-rebreather mask with 100% oxygen is applied while the base hospital is notified of a trauma alert. Vital signs are obtained, and the Glasgow Coma Score (GCS) is measured at a 15. No significant medical history exists. The patient complains of head pain, nausea and dizziness, but is awake enough to deny the presence of any allergies. He relates that he simply lost his footing and fell off the ladder.
During questioning, the patient_s mental status rapidly declines. Both crew members rapidly immobilize his spine and place him on the stretcher. A rapid trauma exam reveals swelling along the right parietal region of the skull. The EMT notes that the patient_s arms and neck are rigidly extended and the feet are flexed downward. The patient_s GCS is reassessed and is now 4ƒeyes 1, verbal 1 anddecerebrate posturing2.
En route, the airway is managed, IV access is established and a second head-to-toe assessment is performed. The GCS remains a 4. BP is found to be 198/124, pulse 58 and respirations 12. Assessment of the pupils reveals constriction on both sides with no response to light. The crew arrives at the trauma center within 12 minutes. During transfer of patient care, the lead caregiver reports his concern of an epidural hematoma.
Although the neurological assessment for this patient may not seem as evident as that for the stroke patient, there were several important items. First, the crew assessed the mechanism of injury. A neurological insult associated with falling 20 feet, landing on concrete and striking the head first has a high probability for a poor outcome. Discovering that the patient was unconscious prior to arrival was also important information.
Second, the crew assessed why the patient fell. It_s possible for a patient to have a medical problem that leads to trauma, which should be discovered by patient and bystander questioning. Third, the crew assessed the level of consciousness during the initial assessment to find that the patient was alert. The first mental assessment is a gross exam to discern if the patient is alert, responsive to verbal stimulus, responsive to pain or unresponsive (AVPU). Once the initial assessment iscomplete, the more comprehensive GCSis assessed and documented. In this case, the GCS score was important because the EMS crew knew that the patient was at a 15 before the sudden deterioration, which is vital information for the receiving facility.
Fourth, the crew noted that posturing was present. It_s possible to miss the presence of posturing during a critical call if the field providers aren_t paying close attention.
Fifth, the pupils were assessed and found to be constricted and non-reactive. Pupils should be assessed any time a neurological injury is known or suspected. They may be unequal, dilated, constricted or non-reactive to lightƒall of which are important determine.
Last, the crew reassessed the GCS to provide objective data on the patient_s deterioration. Putting all the information together resulted in an accurate field impression of an epidural hematoma. Patients with this form of injury can experience a loss of consciousness, appear alert (lucid interval) and then rapidly decline.
A call is received at the 9-1-1 dispatch center for a patient who_s "shaking." Unit 66 isdispatched with two paramedics and an EMT. They arrive at a single-family residence to find a young child being held by an obviously anxious parent. Initial assessment reveals no obvious threats to life; however, the child is alert only to verbal stimulus. His skin also feels hot to the touch.
Assessment of the vital signs reveals nothing out of the ordinary. The pulse oximetry reading is 99% when the crew leader begins to assess the child_s neurological status. The pediatric GCS is calculated to be 13, based on eye-opening on verbal stimulus, crying that can be consoled, and movement that_s spontaneous and purposeful. Knowing history is an important part of the overall neurological assessment, the crew leader asks the parents to describe what happened. The mother relates that the two-year-old began "shaking all over" with his "eyes rolled back in his head." The incident lasted approximately 30Ï60 seconds with no prior history of seizures.
With the parent_s approval, the crew packages and moves the child into the ambulance. Assessment is continued en route with the child_s mental status improving to a GCS of 15. The blood glucose level is determined to be 78 mg/dL. Oxygen is applied and an IV of normal saline is established. During transport, the child actively seizes. Diazepam is administered at 0.1 mg/kg, and the seizure abates within 30 seconds of administration.
Caring for a pediatric patient who_s already experienced a seizure necessitates rapid assessment, transport to a hospital and basic care measures. In this case example, it would have been easy for the crew to assume that the patient had a febrile seizure. It_s not within the scope of EMS practice to render a diagnosis of febrile seizure, and some caregivers have innocently left children at home believing that the seizure was related solely to the rapid increase in temperature. Assessment of seizures requires the field provider to consider multiple possible causes. The popular AEIOU-TIPS mnemonic is a good tool for remembering the various causes.
Expect the patient who experienced a grand mal seizure to present with an altered mental status. Attempt to determine if there_s a prior history of seizures and assess medication compliance for patients with a history of seizure activity. It_s possible for a patient with a specific type of seizure (Jacksonian) to present similarly to a stroke. History can be helpful in distinguishing between the two.
Case #4:Back Pain
EMS is summoned to an assault at a local night club. Police have secured the scene and the two crew members are directed to a patient that was stabbed in the back. A young man in his 20s is lying on his side in a pool of blood but is conscious. He reports that he was stabbed in the back with a switchblade knife that had an approximate 6" blade. No other injuries are noted.
Initial assessment reveals no immediate threat to life, although early signs of shock are beginning to manifest. A 2" wound is noted adjacent to the thoracic spine with blood steadily flowing. A dressing and bandage are quickly applied. Oxygen is administered while the crew works quickly to immobilize the patient onto a backboard. An engine company with three personnel arrives to provide assistance. One of the crew members jumps in the back of the ambulance to prepare two IV setups with large bags of normal saline.
En route to the hospital, oxygen is continued while two IV lines are placed. A physical exam is conducted. The patient is asked to grasp both of the paramedics hands, and a firm grip is noted on both sides. The patient is asked to close his eyes while a strong pinch is applied to each upper extremity with no deficit noted.
The exam is repeated on both lower extremities with very different results. The patient is asked to press his feet downward against resistance of the medic_s hands. No movement is made on the left, but good strength is noted on the right. The same strong pinch is applied to both lower extremities. A clear deficit is noted on the right; sensation is intact on the left. The sensory deficit is present all the way up to the patient_s trunk.
Because the findings are not what were expected, the other EMS provider is asked to confirm them. The same test reveals the same results. Shortly thereafter, the crew arrives at the trauma center and transfers care without incident.
This patient is presenting with classic signs of Brown-Sequard syndrome, which presents clinically with motor deficits on one side accompanied by pain and temperature deficits on the opposite side. It_s found in patients with penetrating injuries that affect only part of the spinal cord and can also be found in patients with spinal tumors, tuberculosis and multiple sclerosis.
The neurological exam for this patient was focused on the upper and lower extremities because of the mechanism of injury. Assessment of motor and sensation are critical components of determining nervous system injury. A simple but efficient method of assessing upper extremity strength for a patient strapped to a backboard is to check grip strength. The lower extremity motor strength can be quickly assessed by asking the patient to press the balls of the feet against the resistance of the EMS provider_s hands, much like pressing on a gas or brake pedal.
Assessing sensation should at least include light touch and pain for all four extremities with a comparison made between the left and right. The examination is conducted with the patient_s eyes closed. Lightly brush the left upper extremity and then the right, and note any deficits. Then, assess both sides simultaneously. Because pain receptors are different than those that detect light touch, the same process should be repeated with a painful stimulus, such as a strong pinch. This examination is repeated for the lower extremities.
When a deficit is noted in one or more extremities, you should continue the sensation assessment proximally to find how much of the body is impaired. Learning the major skindermatomeshelps the prehospital provider detect what level of the spinal cord is impacted.
The nervous system is a vital communication and coordination control center that can be compromised by illness or injury. Assessment of this important system entails gathering a history, performing a physical exam and ruling out other causes (e.g., low blood glucose level). A comprehensive exam can be performed on stroke patients whereas a basic examination is just as important for the trauma patient. Providers should take the time to learn as much as possible about assessing for neurological deficits in an effort to provide excellent care.JEMS
Chad Brocato, DHSc, EMT-P, is the assistant chief of operations with Deerfield Beach Fire-Rescue in South Florida, an adjunct professor of anatomy and physiology at Kaplan University and coordinator for the JEMS Games clinical skills competition. He recently completed a 5-year project to create a fully narrated and interactive online paramedic program, which was released February 2009. Chad also co-owns Emergency Training Solutions in Boca Raton, Fla. Contact him email@example.com.
Learn more from Chad Brocato at the EMS Today Conference & Expo, March 2Ï6 in Baltimore.
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- National Association of EMS Physicians: Role of EMS in the management of acute stroke: Triage, treatment and stroke systems.www.naemsp.org/position.html
- LaCombe DM, Gordon DL, Issenberg SB, et al: "Stroke on the MEND: University of Miami pioneers an innovative stroke curriculum." JEMS. 25(10):32Ï34, 2000.
- American Academy of Pediatrics and American College of Emergency Physicians: APLS: The Pediatric Emergency Medicine Resource, 4th Edition. Jones and Bartlett: Sudbury, Mass., 2004.
- Chu-Shore CJ, Stead SM, Tseng BS: First Seizure: Pediatric Perspective.http://emedicine.medscape.com/article/1179097-overview
- Schreiber D: Spinal Cord Injuries.http://emedicine.medscape.com/article/793582-overview
- National Institute of Neurological Disorders and Stroke: Brown-Sequard Syndrome Information Pa ge.www.ninds.nih.gov/disorders/brown_sequard/brown-sequard.htm