Neurotrauma Review Series—Part 2: What Should a Neurologic Exam Entail?

In this, the second in a series of four articles on neurologic injuries, we will look at the origins of a selective immobilization protocol, consider some of the anatomy involved in a good spinal assessment and discuss the importance of that assessment. This article will also review two very important nerve tracts, which will be featured in coming articles as well.

EMS providers have for years erred on the side of caution and immobilized all of our trauma patients, no matter how slight their trauma, in hopes we’d never miss a spinal injury.¹ As time has gone on, however, we’ve recognized that this practice is inefficient for our providers and could in some cases be detrimental to our patients.

This second notion was given credence with a 1987 study that illustrated association between pressure sores and spinal immobilization in a group of 32 hospitalized patients after prehospital spinal immobilization.² A 1994 study, “The Effect of Spinal Immobilization on Healthy Volunteers,” followed and also raised concerns about unnecessary spinal immobilization.³ Although it also had a small sample size of only 21 volunteers, it demonstrated a link between a 30-minute spinal immobilization period on a long board and complaints of new-onset back pain both during and after.

In July 2000 the National Emergency X-Radiography Utilization Study Group validated the now-famous National Emergency X-Radiography Utilization Study criteria (better known as NEXUS).⁴ In NEXUS, researchers gathered information from 34,069 patients in 21 hospitals across the U.S. who had suffered blunt trauma. Clinicians used criteria based upon patient reliability and examination findings (but not mechanism of injury) to predict which patients needed a cervical spine x-ray and which did not. They then x-rayed the patients’ cervical spines to see who was really injured.

The results shook out like this: Out of the 34,069 patients, 818 had a cervical spine injury on x-ray. The NEXUS physical examination criteria correctly identified all but 8 of those injured patients, and out of the 8 missed, only 2 had injuries that were deemed “clinically significant”⁵ (Injuries categorized as not clinically significant were those that occurred in isolation, without evidence of other bony injury or ligamentous or spinal cord injury; required no specific treatment; and, if not identified, would be very unlikely to result in any harm to patients.⁴)

This made the criteria 99.6 % sensitive for cervical spine injury—pretty good! Many physician medical directors found the study credible and molded their spinal immobilization protocols to mimic the NEXUS criteria. After all, why fully immobilize patients in the field whom we are not going to x-ray in the hospital? Protocols like these are used today in multiple EMS systems, including some in Maine, California and the U.K.^6–8

In one such selective immobilization protocol (based upon NEXUS), there are four criteria for immobilization:⁶

1. Patient reliability—The injured patient must be calm, cooperative, sober and alert. Otherwise they should undergo spinal immobilization.

2. The presence of a painful, distracting injury necessitates spinal immobilization.

3. Complaint of pain or tenderness to the midline posterior spine necessitates spinal immobilization.

4. Neurologic exam—The patient must not exhibit an abnormal sensory/motor exam.

These criteria were taken from the Maine spinal assessment protocol. For more on the details and success of the protocol, see “A Statewide, Prehospital Emergency Medical Service Selective Patient Spine Immobilization Protocol,” John H. Burton, et al., J Trauma, 2006 Jul; 61(1): 161–7.

A Closer Look

The first three criteria in this protocol are straightforward and well worn. The fourth is more interesting. It is all well and good that a protocol dictates that we do a neurologic exam to assess our patients for injury, but of what should that exam consist? Are we all doing similar exams? When we have positive findings, what do those findings really mean? And should we even bother to do an exam on a patient who fails one of the first three protocol criteria?

To try to answer some of these questions, I went back to the training materials from an early Maine spinal immobilization protocol rollout. They say:

If the patient is reliable and without distracting injury, prehospital providers should proceed to a careful and complete neurological examination. This examination should include commonly accepted assessment means for consideration of motor or sensory deficits from spine injury. Any abnormal neurological examination finding(s), including loss of urethral or rectal sphincter control, should direct providers to proceed with spinal immobilization.⁹

This was helpful but not quite what I wanted, so I leaned on a tried-and-true standby: What was I taught in paramedic school? The neurologic exam I learned there was probably similar to what most of us learned early in our careers. It was composed of four parts. It taught me to ask the patient to:

• Pull me toward them using their biceps;
• Abduct their fingers out against my resistance;
• Push down on my hands with their feet; and
• Report whether their hands and feet felt normal (no numbness or tingling) when I touched them.

I used to think these were pretty simple maneuvers and doubted whether I was really doing a good job. Perhaps you have had these thoughts too. We shouldn’t have worried. Although there are more detailed exams aplenty, the brief four-part exam we originally learned, along with observation of a patient’s bladder and bowel continence, is actually useful and well suited for the environment surrounding an EMS call.

Components of a Good Exam

Like the cranial nerve exam, the short neurologic exam can be used effectively without knowing exactly which part of the spine goes with which exam finding. That said, taking the time to master this information can be useful in making the most of your exams. Also like the cranial nerve exam, the neurologic exam works best if you are consistent and methodical (always do all four steps and always do them exactly the same way).

The Motor Exam

1. Biceps—When evaluating bicep function, have the patient grasp both of your hands and then, with their palms facing toward their body, flex their elbows and pull strongly toward their shoulders (Figure 1).

2. Fingers—For the finger abduction assessment, have the patient start with their fingers together and place your thumb and pointer finger on the outside edges of the patient’s thumb and pinky finger. Provide moderate resistance with your fingers as the patient spreads his/her fingers (Figure 2).

3. Feet—For the pedal push (plantar flexion) exam, have the patient sit with his/her feet flat (Figure 3). Almost any sitting position will do as long as there is room for movement beneath the patient’s feet. Place your hands beneath the balls of the feet and have the patient push down on your hands like gas pedals.

To be judged to have “normal” exam findings, all of the patient’s movements should be strong and symmetrical.

The Sensory Exam

For the sensory portion of the exam, touch or gently grasp the skin of the patient’s hands (or wrists) and feet (or ankles) with your hands while they avert their gaze. Have them tell you whether they can feel your hands and whether the sensation feels normal. Ask if there’s numbness or tingling. You can maximize the findings of this test if your hands are a different temperature than the patient’s skin. Ask the patient whether your hands feel warm or cold to them (if you are unsure of the result of this finding, you can use hot and cold packs to assess it as well).

What the Exam Means

If this is the part of the article you’ve been waiting for, then you’re an official prehospital medicine geek, and I am proud of you. This is where we begin to discuss nerve tracts.

In neuroanatomy, the word tract means a bundle of nerves. There are lots of nerve tracts in the spinal cord, and most of them are named for their purpose and location. The tract that transmits nerve impulses from the brain’s cortex down the spinal cord and out to the muscles is situated on the lateral sides of the cord (Figure 4), so it is appropriately named the lateral corticospinal tract. It is damage to the nerves of the lateral corticospinal tract that causes most of the muscle paralysis we associate with cord injuries, and it is the lateral corticospinal tract we’re testing when we ask our patients to move and observe it for strength and symmetry.

The motor nerves (in this context nerves that innervate skeletal muscles) of the lateral corticospinal tract that go to the biceps exit the spinal cord just above the C6 vertebral bone. Therefore, if the patient can exhibit strong, equal bicep flexion, we know the lateral parts of the spinal cord are intact at least from the brain down to C6 (Figure 5). You can remember this by thinking, You need C6 to curl the sodas from your six-pack.

The nerves that abduct the fingers exit the spinal cord just above the T2 vertebra, so if the patient can exhibit finger abduction against resistance, then the lateral corticospinal tract must be intact between the brain and T2. Remember this by thinking of someone holding a teacup with their little finger abducted: If having tea for two, you need T2 to hold your teacup properly.

The motor nerves for the gastrocnemius muscles that plantar-flex the ankles exit the spinal cord at the S1 and S2 vertebrae, so patients who can push on your hands like gas pedals have an intact lateral corticospinal tract between the brain and S1 and S2. Remember this by thinking you need two socks for your two feet: Sock 1 and Sock 2.

The last step in spinal assessment training told me that I should be aware of “loss of urethral or rectal sphincter control.”⁹ The peripheral nerves for the bladder and anal sphincters exit the cord between vertebrae S2 and S4. This finding is a little different than the ones previously described, because our patients’ bladders and rectums are not always full at the time of injury. Dry, clean underwear, therefore, is not always a reliable indicator of lack of injury to the lateral corticospinal tract between the brain and S2–S5. Incontinence, however (when it is not associated with something already resolved, like pressure from a seat belt or reaction to fear), can be an ominous sign. You can remember this by thinking S2 through S4, keep your bowels off the floor.

Sensory information about pain, temperature and crude touch is transmitted from the skin to the part of the brain called the thalamus by a tract located on the anterior and lateral sides of the spinal cord. This tract is called the anterolateral spinothalamic tract (Figure 2). Because they are the most distal parts of the sensory nervous system, an intact sense of touch at the hands and feet demonstrates that the anterolateral spinothalamic tract, and hence the anterior/lateral parts of the spinal cord receiving and relaying information to the thalamus, are undamaged.

Early Detection

Many times, whether we practice with a selective spinal immobilization protocol or not, we decide to immobilize our multitrauma patients without needing to get to a neurologic exam. Even if we have a protocol, our patients often “fail” it early on by being intoxicated or distracted or having midline back pain. What, under those all-too-common circumstances, is the advantage of continuing on to do a simple neurologic exam?

There are two major causes of spinal cord injury. The first is the direct trauma that occurs when a knife or bullet or fence post or piece of broken vertebra actually cuts nerve fibers in the cord. Damage from this kind of trauma is normally permanent because nerve fibers, once severed, do not regrow well. The second cause is the indirect trauma precipitated by inflammation and swelling. Traumatized vertebral bones and disks can cause inflammation and swelling into the spinal canal, and this can temporarily squeeze the spinal cord. Full or partial recovery can sometimes follow this kind of trauma.

Unless you have a pair of MRI sunglasses, it is impossible to discern severed nerve fibers from impinged ones at the scene. You can, however, discern which nerve tracts are still intact very shortly after injury by means of your physical exam, and document that baseline.

What’s the importance of documenting a legitimate neurologic exam? Swelling takes time, and EMS providers often see patients so soon after injury that very little swelling has occurred. Because of this we are in the best position of any medical provider to find out what a patient’s baseline neurologic status really is. When we evaluate our patient shortly after the time of accident and sensory or motor loss is mild or has not yet occurred, it may be surmised that deficits that happen later in treatment are more probably a result of swelling than direct trauma. The physical examination findings we obtain at the scene in neurotrauma patients are not reproducible by any other medical provider because of the effects of time. This means the quality of the assessment that we, and only we, can do at the scene and our documentation of that assessment can make an important difference to emergency physicians, trauma surgeons, critical care physicians, neurosurgeons, neurologists, physical therapy physicians and a host of other providers when they make diagnoses, treatment decisions and prognoses for our patients.

I think that’s important and exciting, and you should too.

References

1. Munk MD. Maine Taps Medics’ Spinal Skills. J Emerg Med Serv, 1997 Mar; 22(3): 76–80, 82–3.

2. Linares HA, Mawson AR, Suarez E, Biundo JJ. Association between pressure sores and immobilization in the immediate post-injury period. Orthopedics, 1987 Apr; 10(4): 571–3.

3. Chan D, Goldberg R, et al. The effect of spinal immobilization on healthy volunteers. Ann Emerg Med, 1994 Jan; 23: 48–51.

4. Hoffman JR, et al. Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma. N Engl J Med, 2000; 343: 94–9.

5. Hoffman JR, et al. Correspondence: Clinical criteria to rule out cervical-spine injury. N Engl J Med, 2000; 343: 1,338–9.

6. Maine Emergency Medical Services. 2011 Maine EMS Prehospital Treatment Protocols, https://www.maine.gov/ems/documents/2011MaineEMSProtocols.pdf.

7. Stroh G, Braude D. Can an out-of-hospital cervical spine clearance protocol identify all patients with injuries? An argument for selective immobilization. Ann Emerg Med, 2001 Jun; 37(6): 609–15.

8. Armstrong BP, et al. Prehospital clearance of the cervical spine: does it need to be a pain in the neck? Emerg Med J, 2007; 24: 501–3.

9. Maine Emergency Medical Services. Spinal Assessment Training Program, https://www.maine.gov/ems/providers/training/spinal-assessment.html.

10. Stiell IG, et al. The Canadian C-Spine Rule for radiography in alert and stable trauma patients. JAMA, 2001; 286(15): 1,841–8.

Tiffany Bombard, NREMT-P, MD, has been an EMS provider, firefighter and paramedic for many years in Vermont, Utah, New York, New Hampshire and Maine. She is currently a resident emergency physician at Albany Medical Center and a paramedic for the Albany County Sheriff’s Office in New York. Contact her at bombieskifast@yahoo.com.