Spinal Cord Injuries

Spinal cord injuries (SCIs) are multidimensional disorders arising from direct or indirect spinal cord damage. The most common cause of SCI is acute trauma from motor vehicle collisions, although the condition may also arise from insidious etiologies such as malignancies and chronic tuberculous infection. Spinal cord lesions may lead to permanent disability, significant morbidity, and mortality. High spinal injuries often impair cardiorespiratory function and require emergent interventions. Nerve axon disruption results in loss of motor and sensory function below the injury level. SCIs disproportionately impact individuals younger than 30, resulting in substantial lifelong functional impairment and potential health, financial, and psychosocial complications. One case of SCI is estimated to have a lifetime economic impact of $2 to $4 billion. Interventions range from initial emergency stabilization to advanced treatments, such as stem cell therapy, which require a long-term commitment. As such, selecting the appropriate therapeutic approach is essential for clinicians across the continuum of care. The spinal cord is a cylindrical structure that extends from the brain caudally through the vertebral column, typically beginning at the base of the brainstem at the medulla oblongata, passing through the foramen magnum, and continues within the spinal canal formed by the vertebrae, terminating at approximately the L1–L2 vertebrae in adults. The spinal cord serves as a critical conduit for communication between the brain and the rest of the body, transmitting sensory signals from the body to the brain through the afferent pathways and motor signals from the brain to the body through the efferent pathways; it also integrates certain reflexes independently of the brain. The spinal cord is divided into segments corresponding to the vertebral levels. Each segment gives rise to spinal nerves supplying specific body regions. The key structures within the spinal cord include the corticospinal (CST) and spinothalamic (STT) tracts, as well as the dorsal columns—nerve pathways that exchange information between the brain and the body. The CST is a major motor pathway responsible for voluntary movement. This nerve tract originates from the motor cortex of the cerebrum and descends through the brainstem and spinal cord. Approximately 90% of the CST fibers travel on the lateral side of the spinal cord, forming the lateral CST (LCST). The LCST nerves travel throughout the cord. The remaining fibers transit ventrally or anteriorly, forming the ventral CST (VCST). However, VCST fibers do not reach levels below the superior thoracic spinal segments.  The STT is a sensory pathway that relays pain and temperature information from the body to the brain. The spinothalamic tract ascends through the anterolateral spinal cord, synapsing in the thalamus before projecting to the somatosensory cortex. Furthermore, the dorsal columns, also known as the posterior columns or dorsal funiculi, convey proprioceptive and tactile sensations (ie, touch, pressure, vibration) from the body to the brain. Dorsal column fibers ascend in the spinal cord's posterior area and consist of the fasciculus gracilis medially and the fasciculus cuneatus laterally. The spinal cord comprises several distinct regions, each corresponding to a specific vertebral segment level. Cervical nerves (C1–C8) supply the neck, shoulders, arms, and hands. Thoracic nerves (T1–T12) innervate the ulnar side of the upper limbs, the trunk, and abdominal muscles. Lumbar nerves L1 to L5 supply the lower back, buttocks, and lower limbs. Sacral nerves (S1–S5) innervate the pelvic organs, buttocks, genitals, and lower limbs. The coccygeal nerve (C0) provides sensory innervation to the skin overlying the coccyx and surrounding areas and also contributes to the motor function of the pelvic floor muscles. Spinal nerve distributions are best represented by dermatomal maps (see . Dermatome Map). The cauda equina consists of spinal nerve roots L2 to S5/C0, extending from the lower end of the spinal cord. The conus medullaris is the terminal portion of the spinal cord and is typically located at the L1 to L2 levels. The filum terminale extends from the conus medullaris and anchors the spinal cord and dural sac to the coccyx, providing structural support to the spinal cord. SCIs result in a wide range of clinical symptoms, each requiring individualized management strategies. Understanding the anatomy and organization of the spinal cord, including the locations of critical nerve pathways, is essential for diagnosing and managing neurological conditions that affect motor and sensory function.