Spinal Cord Injury

Introduction

Spinal cord injury (SCI) is a devastating, life-altering event for patients and their families. In spite of decades of innovative research in the field, no pharmacologic “silver bullet” has been developed that can mitigate or cure the extent of neurologic impairment in SCI patients. Preservation of function by providing early stability to the injured spine followed by neurorehabilitation remains the current standard of care. Surgical decision making should hinge on evaluation and early restoration of the “Holy Trinity” of the spine (alignment, stability, and neurology) to provide the best baseline opportunity for recovery of the injured spinal cord. Compression of neural elements should be mitigated by early surgical management, and episodes of postinjury hypoxia and hypotension should be strictly avoided to prevent secondary insults to the injured spinal cord. A protocol-driven multidisciplinary approach to the management of SCI patients is imperative to reduce the risk for preventable complications and to improve long-term patient outcomes.

• Assume that all trauma patients have a spinal injury until proven otherwise. Start by ensuring that the patient is adequately immobilized while maintaining strict log-roll precautions. Initially, all trauma patients should be placed in a rigid cervical immobilizer. These cervical collars (C-collars) should be kept in place until the cervical spine is “cleared.” Clearance is the process by which the treatment team confirms that a spinal injury is absent. Once this is done, the C-collar can be removed. On the contrary, if a spinal injury is identified, then a spine surgery consult should be placed to determine the proper course of treatment. Patients should be removed from the backboard as soon as possible, using a team-based log-rolling maneuver. Simultaneously, a care provider should inspect the entire spine for external trauma while also investigating for irregularities and areas of palpable step-off. A complete and thorough neurologic examination must occur. Muscle strength is assessed in all myotomes of the four extremities. The sensory examination includes the assessment of light touch, proprioception, pain, and temperature in all dermatomes. A reflex examination is performed to evaluate the upper and lower extremities while also evaluating pathologic reflexes like Hoffmann's and clonus. A complete sphincter examination must also be performed. This includes inspection of the anus, evaluation of perianal sensation with dull and sharp probes, detection of resting rectal tone with digital insertion, evaluation of voluntary anal sphincter contraction, and determination of the presence or absence of the bulbocavernosus reflex. The examiner should also check for priapism. All examination results should be completely and thoroughly documented.

• Members of the treatment team should be aware of the mechanism of injury and the presence of distracting injuries. This knowledge can be invaluable when attempting to assess for SCI because the neurologic examination can be extremely difficult in polytrauma patients who exhibit severe injuries to multiple organ systems. Further complicating the assessment of such patients can be the presence of intoxicating substances that alter the level of consciousness and render a patient uncooperative or unresponsive. Even in severely obtunded patients with multiple concomitant injuries, however, there can be an injury pattern that suggests to the care provider a need to be extremely vigilant about the possibility of SCI. An example of such a scenario is a patient involved in a high-speed MVC who also has severe facial and cranial injuries suggesting a hyperextension mechanism to the neck. In this situation, providers need to be alerted to the likelihood of a significant cervical spine hyperextension injury that could be associated with an SCI. Close evaluation of the cervical spine with advanced imaging is mandatory in this situation.

• The treatment team should adhere to an algorithmic approach to SCI when assessing a trauma patient. The first step must be to ask if a neurologic injury is present. If so, the care provider must ask if the encountered neurologic deficit is attributable to the spine. To do so, neurologic dysfunction associated with cranial or extremity injuries must be considered carefully and then confirmed as absent or occurring simultaneously with the SCI. Once the possibility of an SCI is either identified, excluded, or deemed indeterminate, then the care provider can follow each branch of the decision tree and arrive at an appropriate conclusion regarding surgical decision making.

  Multiply-injured patients with cranial trauma and other injuries can be very difficult to examine. In addition to significant cranial trauma that limits the neurologic evaluation, these patients are also frequently intubated, sedated, and can even be pharmaceutically paralyzed. It is important for the examiner to be aware of these confounding variables. Despite these challenges, it is still possible to obtain important information concerning the neurologic examination and spinal cord function. Flaccid motor tone and absent reflexes should raise suspicion of SCI. In contrast, these findings are extremely unusual with isolated brain injury. When patients cannot be assessed for motor and sensory function, it is important to examine reflexes and also to perform a complete and thorough sphincter examination. Spinal-cord-injured patients typically have flaccid paralysis with associated areflexia. It is important to compare the reflexes of the upper and lower extremities. The examiner should check for priapism. Priapism is common with SCI but is not caused by head injury. The examiner should also perform a thorough anorectal examination. This detailed examination can be a “window” to the spinal cord. Radiographic imaging should also be used liberally when a neurologic deficit is suspected.

• There is a high incidence of noncontiguous spinal injuries when a major spinal injury is identified in a polytrauma patient. Therefore it is imperative to visualize the entire spinal column using a high-resolution computed tomography (CT) scan with reconstructed coronal and sagittal reformations when an SCI is suspected. It is not unusual for such patients to need spinal surgery in more than one spinal region. Furthermore, SCI in more than one site can lead to very complicated neurologic findings. As such, it is imperative that care providers be able to discern these findings based on the various levels of involvement of the neural tissue. Instruments are available to guide the treatment team in proper neurologic assessment. The most important example of this is the American Spinal Injury Association (ASIA) impairment scale.

• A magnetic resonance imaging (MRI) scan of the affected spinal region (cervical, thoracic, lumbar) is important to help clarify the neurologic deficit and is invaluable for surgical planning. This study allows visualization of the neurologic elements and characterization of the location, extent, and type of neural compression. This study is essential for preoperative surgical templating. Spinal surgeons pay close attention to the integrity of the spinal bones and the intervertebral disks and the posterior ligamentous complex (PLC). The PLC includes the ligamentum flavum, the interspinous and supraspinous ligaments, and the facet-joint capsules and the intertransverse ligaments. Injury to the PLC is a significant finding that can render the spinal column mechanically unstable. Spinal surgeons also thoroughly evaluate the morphology of the injury as evidenced by the CT and MRI images. Injury morphology is interpreted carefully to infer the injury mechanism. Once mechanism and morphology are confirmed, then the spinal surgeon couples this information with the neurologic assessment of the patient and the stability of the spinal column, paying close attention to the disco-ligamentous and bony structures. Compiling all of this information soon leads to a conclusive surgical decision-making process.

• Clarifying the neurologic deficit and classifying the injury severity will significantly affect surgical timing. Incomplete SCI is a surgical spinal emergency with the goal of preserving the precious remaining function of the spinal cord. Incomplete injury to the spinal cord involves the preservation of some motor or sensory function below the damaged level. Typically, there is also variable sparing of sacral nerve-root function manifesting as some appreciation of peri-anal sensation and some existence of sphincter control. Cauda equina syndrome (CES) is a surgical urgency that requires decompression of the lumbar nerve rootlets. CES exists as a spectrum of disease ranging from subtle bowel and bladder dysfunction to full-blown flaccid lower-extremity paralysis and loss of sensation with areflexia and complete sphincter incompetence. Complete SCI is a less urgent clinical scenario given the extremely limited potential for neurologic recovery in these patients. Despite this, surgical stabilization of the spine should be strongly considered when appropriate so as to ensure early and safe mobilization of these patients. Early mobilization of critically ill patients is of paramount importance. This will allow prevention of dreaded complications associated with recumbency: pneumonia, urinary tract infections, thromboembolic events, and pressure sores are pertinent examples. Nerve root and plexus injuries are urgent elective conditions that may or may not respond to surgical intervention. Penetrating injuries to nerve roots or the brachial plexus often accompany surgical indications for exploration and repair. Compressive lesions about the nerve roots or brachial plexus (e.g., hematoma, bone or disk fragments, bullets or shrapnel) may also be surgically removed.

  It is mandatory to classify the injury to the spine because this can assist in guiding surgical treatment. Multiple classification systems exist. Pertinent examples include the Subaxial Cervical and Thoracolumbar Injury Classification Systems and Severity-Scores (SLICSS and TLICSS) by the Spine Trauma Study Group and the AO/OTA Spine Injury Classification System by the Orthopaedic Trauma Association (AO/OTA). Although these classification systems can be very detailed and somewhat cumbersome, they all have certain characteristics in common. These characteristics include the analysis of the mechanism and morphology of the injury, the presence and classification of the neurologic injury, and the integrity of the intervertebral disk and posterior ligamentous complex. When considering these three important areas together, spinal surgeons can quickly make conclusions about the necessity for surgery and the desired approach and techniques.

  The classification of SCI relies on the full understanding of the following clinical/neurologic entities:

  • Tetraplegia involves an injury to the cervical spinal cord leading to impairment of function in the upper extremities, trunk, lower extremities, and pelvic organs.

  • Paraplegia involves an injury to the thoracic, lumbar, or thoracolumbar spinal cord leading to impairment of function in the trunk, lower extremities, and pelvic organs. Upper-extremity function is preserved.

  • Pentaplegia is an SCI at or above the C4 level that results in the complete loss of motor, sensory, and reflexive functions below the injured level. Importantly, this also includes paralysis of the respiratory muscles. Patients enduring this type of SCI often remain ventilator dependent.

  • Complete SCI may result from transection, stretch, or contusion of the spinal cord. All function—motor, sensory, and reflexive—below the level of the lesion is lost. This injury is associated with the worst prognosis.

  • Incomplete SCI involves some preservation of motor or sensory function below the neurologic lesion. There is often sacral sparing.

  • Anterior cord syndrome results from an injury of the anterior two-thirds of the spinal cord (the distribution of the anterior spinal artery), which carries motor, pain, and temperature tracts. Vibration sense and proprioception are left intact because the posterior columns are typically preserved. This injury usually stems from a vascular insult. The prognosis is poor.

  • Posterior cord syndrome results from an injury to the posterior one-third of the spinal cord (the distribution of the posterior spinal artery), which carries proprioceptive and sensory tracts. Motor function and interpretation of painful and temperature stimuli are preserved. This injury usually results from a vascular problem, and the prognosis is variable. However, the outlook for patients with this syndrome is much better than for those with anterior cord syndrome.

  • Central cord syndrome results from injury to the central area of the spinal cord. This entity is often found in patients with preexisting cervical stenosis resulting from spondylotic changes. Characteristic deficits are more severe in the upper extremities than in the lower extremities because of the axial arrangement of the neuronal tracts. Distal deficits are more profound than proximal deficits within the limbs. Injury is thought to be a result of buckling of a thickened posterior ligamentum flavum into the spinal cord with an extension moment of the neck. Histological analysis shows there is hemorrhage in the center of the spinal cord. Motor function is typically affected more than sensory function. The prognosis is variable, but there tends to be some clinically detectable recovery. Patients are often left with clumsiness of the hands.

  • Brown–Séquard syndrome is usually seen in penetrating injuries that affect one side of the spinal cord through unilateral hemisection. This entity may also be seen in blunt injury, especially with unilateral traumatically herniated disks. The syndrome results from injury to half of the spinal cord where clinical manifestations result in motor, position, and vibration deficits on the ipsilateral side of the injury, whereas the contralateral side shows deficits in pain and temperature sensation. This pattern of deficits occurs as a result of the decussation level of the neuronal tracts within the spinal cord. The prognosis is typically good.

  • Spinal shock is a clinical syndrome caused by trauma marked by the absence of all spinal cord function below the level of the injury. This condition results in flaccid motor paralysis, complete loss of sensation, and areflexia. As spinal shock evolves, the return of reflex activity begins to occur. This happens in phases and begins with the bulbocavernosus reflex around 48 to 72 hours. Deep tendon reflexes may take days or weeks to return. The term “shock” in spinal shock does not involve end-organ hypoperfusion. Spinal shock, however, can lead to neurogenic shock. Although both of these clinical entities should be recognized, understood, and treated, they should not be confused.

  • Neurogenic shock refers to diminished end-organ perfusion caused by hypotension that can result from cervical or upper-thoracic SCI. Hypotension results from a lack of sympathetic tone below the neurologic lesion. It is characterized by bradycardia from unbalanced vagal input to the heart, decreased systemic vascular resistance, and blood pooling in the extremities. Fluid resuscitation should be used judiciously, and vasopressors should be used to keep the systolic blood pressure (SBP) > 90 mm Hg. Atropine may be necessary to treat bradycardia.

• A pragmatic and simplistic approach to decision making for operative versus nonoperative management in SCI relates to the concept of the “Holy Trinity” of the spine.

  The “Holy Trinity” of the spine is simply defined as “alignment, stability, and neurology.” Elaborating on this concept reveals that a normally functioning spinal column and its associated neurologic elements maintain anatomic alignment, preserve stability under physiological conditions, and manifest normal function of the spinal cord and the nerve roots. When assessing a patient with SCI, the care providers and treating spinal surgeon must ask themselves simple yes/no questions related to spinal alignment, stability, and neurology:

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    Is the spine aligned—yes or no?

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    Is the spine stable—yes or no?

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    Is the spinal neurologic function normal—yes or no?

  If the answer to any of these questions is no, then the spinal surgeon needs to be acutely ready to perform surgery. The answers to the questions related to alignment and neurology are typically straightforward. However, the answer to the question about stability can be somewhat challenging. A working definition of spinal stability should consider that under physiological loads, the spine does not experience increasing deformity, onset of neurologic insult, or a drastic increase in the patient's pain. If spinal stability can be confirmed without the need for surgical intervention, then immediate mobilization of patients with or without bracing may be possible. If the spine is deemed unstable, then early surgical treatment is necessary to enable immediate mobilization. One must also consider the difference between mechanical and neurologic stability. Mechanical stability is often a binary concept—mechanical stability is either present or absent. Neurologic stability is a much more dynamic process that can include rapid improvement or decline. In cases where neurologic improvement begins to abruptly plateau, spine surgeons often consider surgical intervention even if initial closed treatment was indicated. An example of this is a patient with central-cord syndrome who shows initial improvement but then either plateaus or declines in the setting of ongoing neurologic compression.

• The surgical restoration of the “Holy Trinity” of the spine consists of realigning, stabilizing, and decompressing the spine and its neurologic elements. Although spine surgical techniques are many and variable, the goals of providing and maintaining proper spinal alignment, ensuring immediate and rock-solid stabilization, and decompressing impinged neurologic structures remain constant. Spine surgeons may employ anterior approaches, posterior approaches, lateral approaches, or a combination of approaches to ensure that the principles of spinal surgery are upheld. Modern spine surgery techniques often involve the application of screws, rods, plates, and bone grafting, with the ultimate goal being bony fusion. Protection of the neurologic elements is done acutely by meticulous and thorough decompression of the spinal cord and nerve roots, whereas longer-term protection is accomplished by providing stability to the spinal-column around these structures.

  “Holy Trinity” of spinal surgery:

  • Provide and maintain anatomic alignment of spinal segments.

  • Provide immediate, rock-solid stability to the unstable spine.

  • Decompress neurologic structures (brainstem, spinal cord, spinal nerve rootlets, cauda equina, conus medullaris, nerve roots) if indicated and clinically relevant.

  Once spinal injuries are stabilized, immediate mobilization of these critically ill patients must be allowed. After surgery, patients often have ongoing “spinal precautions,” which typically involve some limitation of bending, lifting, and twisting. Even when nonoperative care of spinal injuries is initially considered, if the spinal precautions are too prohibitive to the care team to adequately rehabilitate the patient, then the spine surgeon must consider surgical fixation and stabilization. This will allow removal of activity restrictions and mobility limitations, thus facilitating the proper care by intensivists, therapists, nurses, and SCI specialists.

• After spinal surgery, patients should be placed on an SCI protocol . These patients have a long list of needs that are specific to SCI. All care-team members should be acutely aware of these needs, and treatment should be protocolized to ensure proper delivery of care. Modern trauma centers typically have clinical practice guidelines specifically for SCI that assist the treatment team in caring for these critically ill patients. Examples of such guidelines include the manner in which SCI patients are properly protected from blood clots, skin ulcerations, pneumonia, and gastric bleeding, to name a few common issues. Prophylaxis against these and other commonly encountered complications in SCI patients is paramount. Furthermore, the SCI team should be involved very early in the process of care. The SCI team is typically composed of intensivists, respiratory therapists, physiatrists, and therapists of myriad types who are experienced in delivering care to patients suffering from an acute traumatic SCI. In addition, a multidisciplinary approach to critically injured patients with SCI is mandatory. Explicit communication is required between care providers to ensure all body systems are appropriately managed, with specific attention paid to the effect that serious spinal injury can have on each of these areas. It is also highly recommended to involve clinical social workers and spiritual-care specialists early in the treatment process. These ancillary providers can be extremely helpful in dealing with the psychological and emotional challenges that accompany SCI. This can not only be said of the patient but also of the involved family members. It is also frequently helpful to employ the expert services of a psychologist, psychiatrist, or other behavioral health specialist. In short, the care of SCI patients after surgery is equally or more important than a very well-executed surgical intervention. Patients with SCI should be mobilized by physical therapy (PT)/occupational therapy (OT) in a timely fashion to reduce preventable complications, with the goal of referral to a neurorehabilitation facility at the earliest time point, once all associated injuries have been definitely managed and patients are fully resuscitated.