156: Spinal Cord Injury (Thoracic)

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CHAPTER 156

Spinal Cord Injury (Thoracic)

Jesse D. Ennis, MD, FRCP(C); Jane Wierbicky, RN, BSN; Shanker Nesathurai, MD, MPH, FRCP(C)

Synonym

Paraplegia

ICD-9 Code

344.1  Paraplegia

ICD-10 Codes

G82.20  Paraplegia of both lower limbs, unspecified

G82.21  Paraplegia of both lower limbs, complete

G82.22  Paraplegia of both lower limbs, incomplete

Definition

Spinal cord injury (SCI) is a common cause of paralysis, particularly in young men (Table 156.1). Just more than one third of all injuries to the spinal cord occur at the thoracic level, most commonly at T12 [1]. With thoracic SCI, 68% of patients will have complete injury, 8% will have a sensory incomplete injury, and 23% will have a motor incomplete injury. Mean age at the time of injury has increased over time: from 2005 to 2011, the mean age was 41 years, compared with 28.7 years from 1973 to 1979. Overall, there is still higher representation of males with SCI, with 80.6% of patients being male and 19.6% being female [1]. 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 [2].

A quantitative three-dimensional anatomy of the thoracic spine reveals three distinct zones: the cervical-thoracic transition zone, the middle region, and the thoracic-lumbar transition zone [3,4]. The T1-T4 region is characterized by a narrowing of the vertebral end plate and spinal canal widths [3]. 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) [3]. There is also less rigidity of the spine at the T11 and T12 segments because of the lack of ventral attachment of the ribs [3]. 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 [4].

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 the 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., 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, decreased range of motion, erythema, increased spasticity, pain, and low-grade fever.

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. 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% [5].

Physical Examination

The diagnosis of a thoracic-level SCI necessitates a thorough physical examination, including a comprehensive neurologic 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 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.

Functional Limitations

Persons who suffer from thoracic SCI can have significantly different levels of disability, depending on their degree of paralysis and associated potential complications (e.g., contractures, spasticity). 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. Tasiemski and colleagues [6] 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; reported rates of depression in the newly injured range between 20% and 44% [7]. The most recent large-scale retrospective study of veterans with SCI showed a depression rate of 22% [8]. Depression has been associated with an increase in secondary complications and poor compliance with self-care activities [7]. 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. The stability of the injury is assessed by evaluation of the anterior, middle, and posterior columns of the spine. Magnetic resonance imaging 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 magnetic resonance imaging study to detect osteomyelitis. The triple-phase bone scan is also used in the diagnosis of heterotopic ossification (see Chapter 130). Doppler surveillance studies are sometimes performed to detect deep venous thrombosis in this highly susceptible population (see Chapter 127). Routine colonoscopy and fecal occult blood testing may be appropriate for patients 50 years and older [9]. In patients susceptible to autonomic dysreflexia, appropriate precautions must be used during colonoscopy.

Differential Diagnosis

Amyotrophic lateral sclerosis

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

Skin Management

In an analysis of long-term medical complications among subjects enrolled in the National Spinal Cord Injury Statistical Center database, pressure ulcers were the most commonly reported postinjury complication. McKinley and colleagues [10] reported a 15.2% incidence of pressure ulcers in the first annual follow-up postinjury year. The rates increased steadily during all follow-up years in both complete and incomplete SCIs. 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, weight gain, and incontinence [11].

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 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 148).

Pain

The presentation of pain among the SCI population can be varied in nature; both neuropathic pain and pain resulting from abnormal mechanical stresses (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; however, tricyclic antidepressants, antiseizure medications, and pregabalin have been effective in its treatment but should be prescribed with caution [12].

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 (co-contraction of the bladder and sphincter) is common. 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 (e.g., oxybutynin) or, alternatively, decrease sphincter tone (e.g., terazosin, tamsulosin, or sphincter chemodenervation) [13,14] (see Chapter 137).

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