Lumbosacral spinal cord injury (SCI) refers to impairment or loss of motor or sensory function in the lumbar or sacral segments of the spinal cord, secondary to damage of neural elements within the spinal canal. Conus medullaris syndrome results from an injury to the sacral spinal cord (conus) and lumbar nerve roots within the spinal canal. Cauda equina syndrome refers to injury to the lumbosacral nerve roots within the neural canal. Lumbosacral SCI may manifest with weakness in the legs, lower extremity or perineal sensory loss, bladder and bowel disturbances (urinary retention, constipation, bladder or bowel incontinence), impotence, back pain, and burning perianal or lower extremity pain. Patients may also present with secondary conditions and associated problems, such as urinary tract infections or pressure ulcers. The continuum of SCI care includes initial and post-initial medical and surgical management, initial and ongoing rehabilitation, and life-long sustaining care. The focus of rehabilitation is to minimize impairments and enhance function and participation, with attention to individual personal and environmental factors. An interdisciplinary approach and inclusion of the patient as an active participant in establishment of goals are important elements of care. Coordinated systems of SCI care can reduce complications.
Keywordscauda equina syndrome, conus medullaris syndrome, paraplegia, spinal cord injury
|G83.4||Cauda equina syndrome|
|G83.9||Paralytic syndrome, unspecified|
|S32.009||Unspecified fracture of unspecified lumbar vertebra|
|S34.109||Unspecified injury to unspecified level of lumbar spinal cord|
|S32.10||Unspecified fracture of sacrum|
|S34.139||Unspecified injury to sacral spinal cord|
|Add seventh character for S32 (A—initial encounter for closed fracture, B—initial encounter for open fracture, D—subsequent encounter for fracture with routine healing, G—subsequent encounter for fracture with delayed healing, K—subsequent encounter for fracture with nonunion, P—subsequent encounter for fracture with malunion, S—sequelae)|
|Add seventh character for episode of care for S34|
Lumbosacral spinal cord injury (SCI) refers to impairment or loss of motor or sensory function in the lumbar or sacral segments of the spinal cord, secondary to damage of neural elements within the spinal canal. With this level of injury, arm and trunk functions are spared, but the legs and pelvic organs are involved.
The terms lumbosacral SCI and paraplegia are also used in referring to conus medullaris and cauda equina injuries, but not to impaired sensorimotor function due to injury to neural involvement outside the spinal canal (as in lumbosacral plexus lesions or injury to peripheral nerves). Conus medullaris syndrome results from an injury to the sacral spinal cord (conus) and lumbar nerve roots within the spinal canal. Cauda equina syndrome refers to injury to the lumbosacral nerve roots within the neural canal.
Lumbosacral injuries account for about 11% of traumatic SCI cases in the national Spinal Cord Injury Model Systems database, with L1 being the most common neurologic level. The most frequent causes of injury include motor vehicle crashes, falls, acts of violence, and recreational sporting activities. There is an association between level of injury and cause of injury, and acts of violence are more often associated with paraplegia than with cervical injury and tetraplegia. In addition to trauma, damage to lumbosacral spinal cord and cauda equina may occur due to non-traumatic causes including midline lumbar disk herniation (most commonly at L4-L5), spinal stenosis, tumor, abscess, and hematoma.
Neurologic Versus Skeletal Level of Injury
Lumbosacral SCI refers to the neurologic level of injury, which is different from the skeletal level of injury. Because of the discrepancy between the lengths of the spinal cord and the vertebral column, the L1-L5 lumbar spinal cord segments are typically located at the T11-T12 vertebral level, and the S1-S5 sacral spinal cord segments are at the L1 vertebral level. The spinal cord ends between T12 and L2 (most often at L1 vertebra), and injury within the neural canal below that bone level involves the cauda equina. Lesions at the level of the lowermost thoracic and first lumbar vertebrae may result in mixed cauda equina and conus medullaris lesions ( Fig. 158.1 ).
Lumbosacral SCI may be manifested with weakness in the lower extremities, numbness and tingling, bladder (see Chapter 138 ) and bowel (see Chapter 139 ) disturbances (urinary retention, constipation, bladder or bowel incontinence), impotence, back pain, and burning perianal or lower extremity pain.
There is sometimes a tendency to minimize new symptoms in those with long-standing back problems both on part of the patient and providers. Development of new symptoms of perianal sensory changes or bladder symptoms with increased back pain or sciatica in such patients should be urgently investigated with appropriate imaging and consultation. A high index of suspicion for a hematoma is warranted in patients who develop bladder or sacral sensory impairments postoperatively after spine surgery or while on anticoagulant therapy.
In the outpatient setting, patients may also present with secondary conditions and associated problems, such as urinary tract infections or pressure ulcers. Patients with SCI may have vague, atypical, or nonspecific symptoms. Classic symptoms of urinary tract infection, such as urinary frequency, urgency, and dysuria, may be absent, and patients may present instead with an increased frequency of spontaneous voiding or increased muscle spasms. Fever and malaise may be indicative of a urinary tract infection, but can also be due to other infections (such as osteomyelitis underlying a pressure ulcer) or noninfectious causes, such as osteoporotic long bone fracture, deep venous thrombosis, heterotopic ossification, or drug fever (e.g., due to antibiotics). Unilateral leg swelling may be the only presentation of osteoporotic lower limb fractures, but could also be due to deep venous thrombosis, heterotopic ossification, hematoma, or cellulitis in the setting of SCI.
Pain is a common symptom in people with SCI, and some studies suggest that pain prevalence may be even higher with paraplegia than with cervical injury and tetraplegia. Nociceptive upper extremity pain, most commonly shoulder pain, is reported between 30% and 78% of people with SCI, depending on the population sampled, and neuropathic pain is reported in approximately 35% to 40%. A comprehensive history of pain characteristics is needed to accurately determine the underlying cause, which may be nociceptive, neuropathic, or a combination of both.
New weakness or sensory deficits in the upper extremities may indicate post-traumatic syringomyelia extending into the cervical spinal cord or a peripheral nerve entrapment, such as the median nerve at the carpal tunnel or ulnar nerve at the elbow. Patients with chronic SCI who present with extension or worsening of lower extremity weakness or numbness may have post-traumatic syringomyelia or spinal cord or nerve root compression due to progressive spinal deformity or instability.
Rectal bleeding is often caused by hemorrhoids, but may be a manifestation of more serious disease, such as colorectal cancer. Similarly, hematuria may be due to urinary tract infection, stones, or catheter-induced trauma, but bladder cancer should be considered in the differential diagnosis, especially in smokers and those with chronic indwelling bladder catheters.
Mood disturbances are common in SCI. Depression may be manifested with somatic symptoms such as appetite change and sleep disturbance, although symptoms like loss of energy may be difficult to interpret in the setting of SCI. Because many medical diseases may produce similar somatic symptoms, it is helpful to inquire about specific symptoms typically associated with depression, such as suicidal thoughts, dysphoria, and feelings of hopelessness and worthlessness. Early morning awakening is suggestive of primary depression, and fatigue caused by depression is often worse in the morning.
Spinal Inspection and Palpation
There may be reduced lumbar lordosis due to muscle spasm from pain. Spine fractures may result in deformity, and palpation may reveal areas of tenderness.
Evidence of Concurrent Injuries
Concurrent injuries, including head injury, extremity fractures, and abdominal visceral injury, may accompany lumbosacral SCI and should be considered during physical examination.
Neurologic examination is conducted in accordance with the International Standards for Neurological and Functional Classification of Spinal Cord Injury published by the American Spinal Injury Association. The neurologic findings may sometimes be subtle (e.g., limited to perineal anesthesia or urinary retention) and can be missed in the setting of acute trauma with routine placement of an indwelling catheter or drug-induced sedation, unless they are carefully considered. The neurologic examination should be repeated at regular intervals to monitor for improvement or deterioration.
The required portion of the sensory examination is completed through testing of key points in each dermatome on the right and left sides of the body ( Table 158.1 ) for pinprick (tested with a disposable safety pin) and light touch sensation (tested with cotton). Pinprick and light touch sensation are separately scored at each key point on a 3-point scale: 0, absent; 1, impaired; and 2, normal. In testing for pinprick sensation, inability to distinguish dull from sharp sensation is graded 0.
|Level||Key Sensory Point|
|T12||Inguinal ligament at midpoint|
|L1||Half the distance between T12 and L2|
|L2||Mid anterior thigh|
|L3||Medial femoral condyle|
|L5||Dorsum of the foot at the third metatarsophalangeal joint|
|S2||Popliteal fossa in the midline|
|S4-S5||Perianal area (taken as one level)|
Muscle strength is graded on a 6-point scale of 0 to 5; 0 is no contraction and 5 is normal strength. For the lumbosacral myotomes, five key muscle groups are tested bilaterally ( Table 158.2 ).
|Level||Muscle Group||Position for Testing Key Muscles for Grades 4 and 5|
|L2||Hip flexors (iliopsoas)||Hip flexed to 90 degrees|
|L3||Knee extensors (quadriceps)||Knee flexed to 15 degrees|
|L4||Ankle dorsiflexors (tibialis anterior)||Full-dorsiflexed position of the ankle|
|L5||Long toe extensors (extensor hallucis longus)||First toe fully extended|
|S1||Ankle plantar flexors (gastrocnemius, soleus)||Hip in neutral rotation, knee fully extended, and ankle in full plantar flexion|
Neurologic Rectal Examination
Neurologic rectal examination includes determination of deep anal sensation and testing for voluntary contraction of the external anal sphincter around the examiner’s finger (graded as present or absent). If there is voluntary contraction of the anal sphincter, the patient has a motor incomplete injury.
Additional Neurologic Examination
In addition to these required elements for neurologic classification of SCI, position and deep pressure sensation and muscle strength of additional lower extremity muscles, such as medial hamstrings and hip adductors, are also tested. Examination also includes assessment of muscle stretch reflexes, muscle tone, anal sphincter tone, bulbocavernosus reflex, and plantar reflexes.
Conus Medullaris and Cauda Equina Injuries
The examination will vary with the level of damage and the relative involvement of the conus and cauda equina and may include evidence of lower or upper motor neuron involvement. Patients with injury above the conus medullaris typically present with signs consistent with upper motor neuron or suprasacral SCI, whereas those with injury below this level present with a clinical picture consistent with lower motor neuron impairment. Lesions affecting the transition between the two regions (typically around L1 vertebral-level injury) can have a mixed picture. Conus medullaris lesions typically result in impaired sensation over the sacral dermatomes (saddle and perineal anesthesia), lax anal sphincter with loss of anal and bulbocavernosus reflexes, and sometimes weakness in the lower extremity muscles. Cauda equina involvement results in asymmetric atrophic, areflexic paralysis, radicular sensory loss, and sphincter impairment.
Skin examination is conducted with particular attention to the areas most vulnerable to pressure ulcer development. These include the sacrum-coccyx, heels, trochanters, and ischial tuberosities.