Abstract
Spinal cord injury (SCI) is a major cause of paralysis and disability, with more than one-third of all injuries occurring at the thoracic level. Injury to the thoracic spinal cord, with its unique anatomy, rib articulation, and innervation of the abdominal and intercostal muscles, results in paraplegia and upper motor neuron findings. Patients present with paraplegia, sensory loss, autonomic dysfunction, and alteration in bowel and bladder function. Complications may arise immediately, or years later, and include autonomic dysreflexia, postural hypotension, deep vein thrombosis, heterotopic ossification, respiratory compromise, spasticity, skin ulcers, pain, and bowel and bladder dysfunction. Depending on the level and severity of injury, patients with thoracic SCI may have significantly different levels of impairment of body structure and function, disability, and function. Rehabilitation of the spinal cord injured patient can be challenging, requiring a focus on not only the acute medical conditions, but also on prevention of complications, and optimization of function and independence.
Definition
Spinal cord injury (SCI) is a lesion of the neural elements in the spinal canal, resulting in temporary or permanent sensory deficit, motor deficit, and/or bowel/bladder dysfunction. SCI is a common cause of paralysis, particularly in young men. Motor vehicle accidents continue to be the most common etiology of SCI, followed closely by falls ( Fig. 157.1 ). Over one-third of all injuries to the spinal cord occur at the thoracic level, most commonly at T12. With thoracic SCI, 67% of patients will have complete injury, 8% will have a sensory incomplete injury, and 24% will have a motor incomplete injury. Mean age at the time of injury has increased over time: from 2010 to 2015, the mean age was 42 years, compared with 29 years from 1972 to 1979. Overall, there is still higher representation of males with SCI, with 81% of patients being male and 19% being female. Compromise to the thoracic spinal cord typically results in paraplegia. Unlike paraplegia that results from compromise of the cauda equina associated with lumbar spine injuries, the clinical findings are consistent with upper motor neuron injury. However, lower limb paralysis is not the only impairment. The thoracic spinal cord also segmentally innervates the intercostal muscles as well as the upper and lower abdominal muscles. The intercostal muscles are innervated by the T1 to T12 spinal segments. The upper abdominal muscles are innervated by the T8 to T10 spinal segments; the T11 to T12 spinal segments innervate the lower abdominal muscles.
A quantitative three-dimensional anatomy of the thoracic spine reveals three distinct zones: the cervicothoracic transition zone, the middle region, and the thoracolumbar transition zone. The T1 to T4 region is characterized by a narrowing of the vertebral end plate and spinal canal widths. The middle thoracic region (T4-T9) is notable for its relatively narrow end plate and small spinal canal. The rib articulations provide an increased degree of protection at this level. An enlargement of the spinal canal characterizes the lower thoracic region (T10-T12). There is also less rigidity of the spine at the T11 and T12 segments because of the lack of ventral attachment of the ribs. Therefore, there is an increased vulnerability to SCI at the lower thoracic levels. Compared with the cervical and lumbar spinal levels, the blood supply is more tenuous in the thoracic spinal cord, and therefore ischemia poses a greater threat to neurologic function in this area.
Symptoms
The presenting symptoms of thoracic SCI are consistent with the alteration to the motor, sensory, and autonomic pathways. The chief symptoms are weakness or paralysis of the abdominal and lower extremity musculature and loss of sensation in the lower limbs, thorax, and perineum. Patients may also experience altered bowel or bladder function in addition to spasticity and sexual dysfunction.
With lesions above the T6 level, patients may experience symptoms of autonomic dysreflexia. Autonomic dysreflexia is characterized by pounding headaches, nasal congestion, anxiety, visual disturbances, pallor below the level of injury, and sweating and flushing above the level of injury. In patients with an old, stable injury who are experiencing new or progressive symptoms (e.g., pain, increasing weakness, loss of sensation), the clinician should consider the possibility of a syrinx.
Patients with SCI are often insensate to the pain that accompanies deep venous thrombosis, and therefore both the clinician and the patient should be attentive to clinical signs such as edema, erythema, and increased tone. Heterotopic ossification may mimic deep venous thrombosis because the symptoms include swelling, warmth, erythema, increased spasticity, pain, low-grade fever, as well as decreased range of movement.
Pain can originate from musculoskeletal, visceral, or neuropathic pain generators. An analysis of several studies addressing prevalence of pain after SCI showed a variable overall prevalence of pain ranging from as low as 26% to as high as 96%. Pain originating from either musculoskeletal or neurologic sources is common. Neuropathic pain resulting from central or peripheral nervous disruption may be described as burning or shooting. Chronic visceral pain is found in approximately 30% of the population and is often associated with constipation, while neuropathic pain is present in 40% to 50% of patients.
Physical Examination
The diagnosis of a thoracic-level SCI necessitates a thorough physical examination, including a comprehensive American Spinal Injury Association (ASIA) assessment. Findings on physical examination include a motor and sensory level. Depending on whether the injury is partial or complete, there may be sparing of sacral sensation or anal sphincter motor function below the neurologic level of injury. In the acute period, the motor examination is characterized by loss of muscle tone and deep tendon reflexes. During subsequent days and weeks, there is emergence of increased muscle tone, reflexes, and pathologic reflexes. Cutaneous reflexes including the plantar response, cremasteric reflex, and bulbocavernosus reflex are initially depressed and follow a variable course to gradual return. The neurologic level of injury should be reassessed once spinal shock has resolved, as it may be different from previous assessments. The initial evaluation of the patient also includes the assessment of vital signs and the cardiovascular, respiratory, musculoskeletal, gastrointestinal, and genitourinary systems. A thorough examination of the skin is necessary. In thoracic SCI, pressure ulcers are more common over bone prominences such as the sacrum, calcaneus, and greater trochanter. In addition, it is important to evaluate the patient for spasticity and contractures.
New neurologic abnormalities on physical examination should alert the clinician to consider imaging studies to exclude syringomyelia. In this case, typical physical examination findings include change in sensory level, change in motor level, and reflex abnormality as well as spasticity. However, there are individuals with radiological evidence of syringomyelia, but no recognizable clinical symptoms.
Functional Limitations
Persons who suffer from thoracic SCI can have significantly different impairments and levels of disability, depending on their degree of paralysis and associated potential complications (e.g., contractures, spasticity). For example, a patient with high thoracic paraplegia (i.e., T2 level) typically has some component of truncal instability; as a result, the patient’s wheelchair requires a high back. In contrast, a person with low thoracic paraplegia generally has preservation of most of the intercostal and abdominal muscles and could opt for a chair with a low back. Intercostal muscle impairment in patients with SCI in the upper thoracic region may cause an impaired cough and a decreased ability to mobilize secretions.
Functional goals for individuals with thoracic SCI include the ability to complete activities of daily living and instrumental activities of daily living with or without the use of assistive equipment. At 1 year, approximately 12% of patients return to work and this increases to 34% at 20-year follow-up. Tasiemski and colleagues have described a positive association of involvement in sports and recreational activities with increased life satisfaction in a community sample of people with SCI. Numerous sports and recreational organizations offer adaptive sports programs for people with disabilities.
Bowel and bladder function may cause social embarrassment, leading to self-imposed social isolation. Sexual dysfunction may result in a loss of intimacy. The availability of partners is a concern for many patients because their disability as well as environmental and social barriers may preclude their involvement in some of the more typical dating activities.
Depression is common in patients with SCI; a recent meta-analysis found the prevalence of depression to range between 19% and 26%. Depression impacts the rehabilitation process, negatively affecting the level of participation in therapeutic programming and resulting in poor compliance with self-care activities. Referral to mental health professionals is encouraged for patients at risk.
Diagnostic Studies
The diagnosis of thoracic SCI is often corroborated with magnetic resonance imaging (MRI). The stability of the injury is assessed by evaluation of the anterior, middle, and posterior columns of the spine. MRI is also the study of choice when syringomyelia is suspected.
Urodynamic testing is commonly used to evaluate bladder function in the individual with SCI. Urodynamic studies involve filling of the bladder with fluid or gas and use of electromyographic and fluoroscopic techniques to evaluate voiding function. Annual evaluations often include an ultrasound examination to further assess the integrity of the renal system.
Patients with grade IV pressure ulcers may require a bone scan or MRI study to detect osteomyelitis. The triple-phase bone scan is also used in the diagnosis of heterotopic ossification (see Chapter 131 ). Doppler surveillance studies are sometimes performed to detect deep venous thrombosis in this highly susceptible population (see Chapter 128 ). Computer tomography pulmonary angiogram is employed in cases of suspected pulmonary embolism. Routine colonoscopy and fecal occult blood testing may be appropriate for patients 50 years and older. In patients susceptible to autonomic dysreflexia, appropriate precautions must be used during colonoscopy.
Amyotrophic lateral sclerosis
Hereditary spastic paraplegia
Post-traumatic syringomyelia
Guillain-Barré syndrome
Spinal cord infarction
Ischemic injury to spinal cord (i.e., secondary to abdominal and thoracic aneurysms)
Multiple sclerosis
Transverse myelitis
Treatment
Initial
The initial management of SCI consists of medical stabilization of the patient, immobilization of the spine, and procurement of relevant medical imaging to determine etiology and extent of injury. In the case of traumatic SCI, Advanced Trauma Life Support (ATLS) protocol should be initiated. Any mobilization of the patient should incorporate logrolling to ensure anatomic alignment of the spine. A back board is used for immobilization of the spinal cord, but should be discontinued as soon as possible to prevent pressure ulcers. Imaging of the spine includes computed tomography to visualize bony structures and MRI for soft tissue visualization. Suspected infection and cancer of the spinal cord should warrant blood work, inflammatory markers, and MRI. Damage to the spinal vasculature and thrombosis requires contrast angiography.
Skin Management
The prevention of skin ulcers is paramount. In a long-term analysis of subjects enrolled in the National Spinal Cord Injury Statistical Center database, skin diseases were the second most common cause of re-hospitalization. Gélis and colleagues reported a 15% to 30% prevalence of pressure ulcers in the chronic stages of SCI. Common sites for pressure ulcers are the sacrum, greater trochanter, and heels. Excessive pressure, shearing, friction, and maceration can increase the risk for pressure ulcers. Other risk factors include spasticity, impaired sensation, immobility, poor nutrition, heterotopic ossification, weight gain, and incontinence.
The maintenance of skin integrity is an ever-present goal in patients with SCI. Pressure ulcer formation will lead to the development of scar tissue and an even greater likelihood of ulcer recurrence. Seating surfaces should be reevaluated on a regular basis, ensuring that they have not worn out and still fit the patient’s weight and size. Patients are encouraged to perform daily skin examinations, and most paraplegic patients are able to independently perform pressure-relieving strategies, such as wheelchair pushups. These techniques should be performed every 15 minutes to minimize excessive pressure. Patients immobilized in bed should be turned and repositioned every 2 hours.
Patients who have a pressure ulcer must minimize pressure to that area until the wound is healed. A variety of débridement methods are available for removal of necrotic debris from pressure ulcers (see Chapter 149 ).
Pain
The presentation of pain among the SCI population can be varied in nature; both neuropathic pain and pain resulting from abnormal mechanical stresses on the musculoskeletal system (e.g., tendinitis) are common. Many times, patients with musculoskeletal pain have a well-defined disorder that is amenable to standard physiatric treatment (e.g., rotator cuff tendinitis, lateral epicondylitis). Non-narcotic analgesics and nonsteroidal anti-inflammatory drugs can be used to treat musculoskeletal causes of pain. Neuropathic pain generally is not responsive to these medications, but there is strong support both for the usefulness and safety of pregabalin. Medications such as gabapentin, amitriptyline, and duloxetine may also be effective.
Bladder Management
Most patients with thoracic-level SCI will have upper motor neuron bladder dysfunction, characterized by low urinary volumes, high bladder pressures, bladder trabeculation, and diminished bladder compliance. Detrusor-sphincter dyssynergia (contraction of the bladder wall with incomplete relaxation of the urethral sphincter) is a common occurrence. This can contribute to vesicoureteral reflux, which may result in hydronephrosis and subsequent chronic renal failure. Detrusor-sphincter dyssynergia can be treated with medical interventions that decrease bladder tone such as antimuscarinics (e.g., oxybutynin) or β 3 agonists (e.g., mirabegron), although high level evidence for the latter is lacking. Alternatively, α-adrenoreceptor blockers (e.g., terazosin, tamsulosin) may be used if there is evidence of a non-relaxing bladder neck or benign prostate enlargement. Detrusor or sphincter chemodenervation through the use of botulinum toxin has also been shown to be beneficial (see Chapter 138 ).
Bladder management strategies should be individualized, but intermittent catheterization is the preferred treatment option. A typical intermittent catheterization program requires bladder emptying four to six times per day, with bladder volumes remaining less than 500 mL. Most paraplegic patients have the manual dexterity to perform self-catheterization; some individuals, because of physical or sociomedical factors, must use indwelling catheters (with suprapubic preferred to urethral). Indwelling catheters are associated with a higher incidence of bladder stones and bladder carcinoma. In addition, in men, urethral catheters are associated with prostatitis, epididymitis, and urethral strictures. Long-term use of urethral catheters in women may result in urethral dilation.
Bowel Management
The patient with thoracic-level injuries will most likely have constipation; therefore, a bowel program is necessary. A reasonable goal for a bowel regimen is to achieve socially acceptable fecal continence, with bowel evacuations at least three times per week. A bowel regimen may include medications ( Table 157.1 ). In addition, bowel evacuation is scheduled after a meal to capitalize on the intrinsic increase in peristalsis after meals (i.e., the gastrocolic reflex). Bowel care programs done on a raised toilet seat use the benefits of gravity. Digital stimulation (gentle insertion of the finger) of the rectum or insertion of a suppository can activate the rectocolic reflex by stimulating peristalsis and promoting regular bowel movements. Enemas (Fleet, soapsuds) should not be part of a regular bowel program. However, these agents are useful in emptying the colon before initiation of a bowel program or treatment of fecal obstipation. The administration of an enema, suppository, or digital stimulation can precipitate autonomic dysreflexia in susceptible patients. If administration of an oral osmotic laxative is required, consideration should be given to polyethylene glycol 3350 (PEG 3350) over the traditional use of lactulose. This is supported by a recent Cochrane review that demonstrated greater efficacy and less abdominal pain compared with lactulose for all-cause chronic constipation (see Chapter 139 ).
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