Spinal cord injury (SCI) is a serious medical condition, which often results in severe morbidity and permanent disability. It occurs when the axons of nerves running through the spinal cord are disrupted, leading to loss of motor and sensory function below the level of injury. Injury is usually the result of a major trauma, and primary injury is often irreversible. These injuries are particularly costly and disabling as they disproportionately affect patients under 30-years-old, lead to significant functional impairment for the remainder of the individual’s life, and put the individual at risk for numerous complications leading to increased morbidity and mortality. SCI is estimated to have a lifetime economic impact of 2 to 4 billion dollars.
Within the United States, the leading cause of spinal cord injury is motor vehicle collisions, constituting 38% of new SCI each year. 30% are due to falls, 13% due to violence, 9% from sports injuries, and 5% from medical and surgical etiologies.
Globally, between 250,000 and 500,000 patients each year suffer a spinal cord injury. Most of these cases are due to preventable causes such as violence and motor vehicle accidents. In the United States, there are approximately 17,000 new cases of SCI each year, and roughly 282,000 persons estimated to be living with SCI. Males represent the majority of patients with SCI related to a sports injury. The age group with the highest risk of SCI is from 16 to 30 years of age.
Spinal cord injuries are most often due to either direct trauma to the spinal cord or from compression due to fractured vertebrae or masses such as epidural hematomas or abscesses. Less commonly, the spinal cord may become injured due to compromise of blood flow, inflammatory processes, metabolic derangements, or exposure to toxins.
SCI results from initial insult such as mechanical forces to it, which is known as the primary injury. The most common mechanism of primary injury is a direct impact, and persistent compression typically occurs by bony fragments through fracture-dislocation injuries. Contrary to fracture-dislocation, hyperextension injuries usually result in less frequent, impact alone plus transient compression. The third mechanism, distraction injury, a stretch and tear of the spinal cord in its axial plane, occur by pulling apart of two adjacent vertebrae. Lastly, laceration/transection injury, which arises through sharp bone fragments, severe dislocations, and missile injuries.
Secondary injury is a series of biological phenomena that begins within minutes and continue to self-immolation for weeks or months following the initial primary injury. The acute phase of secondary injury begins after SCI and involves vascular damage, ionic imbalances, free-radical formation, the initial inflammatory response, and neurotransmitter accumulation (excitotoxicity). The subacute phase follows, which includes demyelination of surviving axons, Wallerian degeneration, matrix remodeling, and formation of the glial scar.
Immune Response Spinal Cord Injury
Neuroinflammation can be either beneficial or detrimental following SCI, providing time-point and the state of immune cells. The first three days following SCI, inflammatory events involve recruiting blood-born neutrophils resident microglia and astrocytes to the injury site. The second phase, approximately three days post-injury, enrolls macrophages, B- and T-lymphocytes to the injury site. CD4+ helper T become activated by antigen-presenting cells and release cytokines that subsequently stimulate B cell to synthesize and release antibodies, which exacerbate neuroinflammation and subsequent tissue destruction. Neuroinflammation is more robust in the acute phase of SCI.
Ongoing inflammation may persist in subacute and chronic phases, even for the rest of a patient's life. Inflammatory cell composition and phenotype alter according to the stage of inflammation and the signals existing in the injury microenvironment. T cells, B cells, and microglia/macrophages are capable of gaining either pro-inflammatory or an anti-inflammatory pro-regenerative phenotype.
Disruption of nerve axons running through spinal cord tracts leads to loss of motor and sensory function below the level of injury. Patterns of disability are dependent on the level of the injury and which spinal tracts are affected.
Spinothalamic tracts run within the anterior aspect of the spinal cord. These nerve axons carry sensory information for pain and temperature. Damage to these tracts leads to contralateral loss of pain and temperature sensation. Corticospinal tracts run within the lateral aspects of the spinal cord. These nerve axons control motor function. Damage to these tracts leads to ipsilateral weakness or paralysis. In the cervical spine, axons leading to the upper extremities are located close to the center of the spinal cord.
In contrast, axons leading to the lower extremities are located on the periphery. The dorsal columns run within the posterior aspect of the spinal cord. These tracts carry information for tactile, proprioceptive, and vibratory sensation. Damage to these tracts leads to contralateral loss of tactile, proprioceptive, and vibratory sensation.
Typically patients will present after a significant traumatic event such as a motor vehicle accident, fall from a height, or gunshot wound. Vitals are unlikely to be abnormal, although high cervical injuries can result in hypotension and bradycardia due to loss of sympathetic tone. The physical exam will reveal weakness and sensory deficits correlating to the pattern of injury, and the spinal tracts affected. Several classic patterns of injury are well described.
Complete Transection of the Spinal Cord 
Central Cord Syndrome
Anterior Cord Syndrome
Posterior Cord Syndrome
Brown-Séquard Syndrome 
Conus medullaris Syndrome
As spinal cord injuries most often occur in the context of significant trauma, a comprehensive physical examination and clinical assessment for concurrent injuries are necessary at the time of presentation. Recognition of the above injury patterns can help localize the location and type of injury suffered. Clinical examination with a detailed and accurate examination of motor and sensory nerves is essential for classification.
SCI is graded using the American Spinal Injury Association (ASIA) Impairment Scale. The grading system varies based on the severity of injury from letters A to E.
Imaging is vital to identify the injuries accurately. Plain radiographs have been used traditionally, however with advancing technology and poor sensitivity with plain radiographs, computerized tomography (CT or CAT scan) has replaced as the initial screen to identify bony abnormalities like fractures. CT can reveal vertebral fractures and raise suspicion for SCI; however, it has very poor sensitivity for soft tissue injuries. Magnetic resonance imaging (MRI) is needed to accurately assess the level of injury to the spinal cord itself. MRI can help with prognostication, and several clinical scores use this to predict prognosis. Early spinal cord injury findings see on an MRI include spinal cord compression, spinal cord contusion, spinal cord edema, spinal cord transection, spinal cord hemorrhage, and ligamentum flavum bulging. Subacute findings include spinal cord edema, subacute progressive ascending myelopathy, and syrinx.
Other associated imaging findings may include:
Treatment begins at the site of injury and paramedics, and emergency medical services staff can play a significant role in stabilization before transfer to the hospital. Immobilization can help prevent the worsening of any existing injuries. In the case of serious trauma, address any life threats or concurrent traumatic injuries immediately.
High dose methylprednisolone therapy has shown to be protective in spinal cord injuries, though the efficacy is very limited, and the impact on outcomes is marginal.
Hypotension and shock will worsen the impact of any existing SCI and worsen the likelihood of neurologic recovery. Immediate measures are necessary to maintain breathing and hemodynamic stability. Surgical decompression may be warranted if feasible to lessen the extent of the injury. This procedure helps to stabilize the spine, to prevent pain, reduce deformity, deliver compression from a herniated disc, blood clot or foreign body.
Patients with SCI are best managed in neurological intensive care units with expertise in managing such patients. Dedicated trauma units must be identified and designated to transfer and care for these patients.
Rehabilitation is an integral part of healing, and these patients have the best possible outcomes with intense rehabilitation therapy under the guidance of physiatrists, physical therapists, and occupational therapists. Rehabilitation is to be continued on an outpatient basis once the patient is ready for discharge from the inpatient rehabilitation unit.
Several medications have had trials to help with improving outcomes in SCI, but the results have not shown significant benefits. Trials with nimodipine, gacyclidine, thyrotropin-releasing hormone, riluzole, gangliosides, minocycline, magnesium, acidic fibroblast growth factor have been studied to see their impact on improvement in patients with SCI. At the current time, further research is necessary with regards to these agents, and high dose steroids are the mainstay for acute treatment of SCI.
The diagnosis of spinal cord injury will likely be relatively precise based on the patient’s presentation, which will probably be following a major traumatic event. However, when the time of onset and preceding events are less clear, a broader differential for motor and sensory deficits should be considered.
Central Nervous System Pathologies
Peripheral Nerve Pathologies
Neuromuscular Junction Pathologies
The prognosis for patients with spinal cord injury is very poor. Unfortunately, there is no definite treatment leading to recovery for SCI. Less than 1% of patients with SCI recover complete function before the time of hospital discharge. The level of disability suffered directly correlates to the level of injury, with higher-level injuries resulting in more significant disability and higher complication rates. Patients will SCI suffer significantly increased mortality in the first year following injury, and those that survive still have decreased life expectancy. Only 12% go on to hold employment, and less than one half will get married.
Spinal cord injuries are associated with numerous complications such as urinary tract infections, pressure sores, deep vein thromboses, autonomic dysreflexia, and chronic pain.
Autonomic dysreflexia occurs in individuals with SCI at or above thoracic spinal level 6 (T6). This condition often manifests as orthostatic hypotension. The symptoms of orthostatic hypotension are often challenging to treat. Symptomatic management with abdominal binders, elastic stockings, peripheral vasoconstrictor medications like midodrine, and mineralocorticoids like fludrocortisone can help. Increased salt intake can also help with volume expansion and help with symptom control.
The most common causes of mortality are pneumonia and sepsis.
Spinal cord injury is very stressful and overwhelming for the patient and the families. Patient education must be an important part of the clinical management of patients with this condition. Counseling is necessary regarding prognosis, complications, and outcomes. Support groups can help with the management of issues like anxiety, frustration, loneliness, and depression. The patient should receive counsel about the diagnosis and the prognosis. Prevention centers can help with mitigating factors leading to traumatic injuries like improvement in motor vehicle safety, gun control, and social programs aimed at the prevention of violence.
Once a patient has suffered spinal cord injury, their quality of life and life expectancy is dependent upon continued well-coordinated care between an interprofessional healthcare team. A team approach is ideal for helping mitigate the many complications that can result from SCI :
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