Definition

Transverse myelitis is a focal inflammation across the spinal cord along one or more levels. This inflammation can cause damage to the ensheathing nerve cell fiber myelin, with resultant nervous system dysfunction [1]. The diagnosis may incorporate the terms acute, meaning arising suddenly and intensely, and idiopathic, in which no specific bacterial, viral, or other obvious inflammatory cause can be found. Other descriptors include acute partial, acute complete, and longitudinally extensive. Few population-based studies are available, and comparative or meta-analysis of the literature is difficult because of the different presentations of transverse myelitis being reported. It appears, however, that acute transverse myelitis is rare, with only 1400 new cases annually in the United States, or 1 to 4 cases per million population per year [1,2].

An older study from 1993 in the United States on acute or subacute noncompressive myelopathy showed these cases to be 45% parainfectious, 21% multiple sclerosis, 12% spinal cord ischemia, and 21% idiopathic [3]. With the availability of improved diagnostic tools, possible changes in disease patterns, and longer follow-up, the etiology of transverse myelitis may be clearer. A 2012 study from France on acute partial transverse myelitis with a median follow-up period of 104.8 months reported the etiology of cases as 62% multiple sclerosis, 1% postinfectious myelitis, 1% neuromyelitis optica, 1% Sjögren syndrome, and 34% undetermined (i.e., idiopathic) [4]. However, another French multicenter retrospective study applying the Transverse Myelitis Consortium Working Group criteria [2] for acute transverse myelitis to 288 subjects was more evenly spread. It reported the etiology as 20.5% systemic disease (systemic lupus erythematosus, Sjögren syndrome, antiphospholipid syndrome), 18.8% spinal cord infarct, 10.8% multiple sclerosis, 17.3% infectious or parainfectious, 17% neuromyelitis optica, and 15.6% idiopathic acute transverse myelitis [5].

There is a female predominance of 60% to 75% [4–9] and a bimodal age distribution. Patients having transverse myelitis related to multiple sclerosis, postinfectious transverse myelitis, or idiopathic transverse myelitis are younger, whereas those with transverse myelitis related to spinal cord infarcts or delayed radiation effects are older [4,6,8,10]. Transverse myelitis may recur, with reported rates ranging from 17.5% [9] to 61% [8], and relapse appears to be more common with acute partial transverse myelitis [11].

According to one magnetic resonance imaging (MRI) study, idiopathic acute transverse myelitis most commonly affects the cervical region (60%), followed by the thoracic region (33%) [5]. The onset of transverse myelitis can be acute (within hours or days) or subacute (between 1 and 4 weeks) [1,3]. The period from onset to complete weakness in idiopathic transverse myelitis has been reported to range from 10 hours to 28 days, with a mean of 5 days [10]. Subacute presentations, progressing over days to weeks and ascending, are associated with a good to fair prognosis. Acute and catastrophic presentations with back pain have a poorer outcome [12].

Symptoms

Patients with transverse myelitis may present in the ambulatory clinic or hospital setting with complaints of weakness of the arms and legs, pain, sensory impairments, or difficulties with the bowel and bladder. Weakness may affect the lower limbs or all four limbs with varying severity. Sensory complaints may include hypersensitivity, numbness, tingling, coldness, or burning. Pain is a common symptom in a third to one half of patients and may be localized or shooting in character. Bowel frequency or constipation may occur, and bladder symptoms include increased frequency, retention, and incontinence [1,10].

The history may reveal symptoms of recent infection, immunocompromised or autoimmune condition, space-occupying lesion, demyelinating disease, travel, vaccination, trauma, sexual exposure, animal bites, and insect or tick bites. A careful review may yield systemic symptoms, including the upper respiratory tract with cough and difficulty in breathing, chest pain, rashes, joint aches, muscle pain, vision changes, nausea, diarrhea, constipation, and problems with urinary function. Particular attention should be paid to details pointing toward potentially treatable or reversible conditions responsive to antimicrobials or surgical decompression.

Any history of invasive spinal intervention for pain management should be explored. Cases of acute paraplegia with sensory, bowel, and bladder dysfunction have been reported after epidural steroid injections and lumbosacral nerve root blocks. Inadvertent direct cord injury may occur, or a vascular injury resulting in cord infarction may be the cause [13–15]. Damage to an abnormally low artery of Adamkiewicz as it travels with the nerve root through the neural foramen has been postulated. This dominant radiculomedullary artery arises between T9 and L2 levels in 85% of people, but it may arise from the lower lumbar region to as low as S1 [15]. There has also been a report of transverse myelitis resulting from the infected catheter tip of an intrathecal morphine pump for chronic pain [12].

Physical Examination

The physical examination follows a thorough history taking and will focus on the manifestations and findings relating to myelopathy, such as motor weakness, changes in sensation (pinprick, light touch, vibration, position sense, or temperature), tone, muscle stretch reflexes, coordination, and bowel and bladder functioning. Changes affecting the brain, such as cognitive dysfunction and cranial nerve and visual abnormalities, are generally not seen with idiopathic transverse myelitis and suggest other diagnoses.

Temperature elevation, tachycardia, and tachypnea may indicate an infectious etiology. Infections and autoimmune conditions that cause acute inflammation of the spinal cord may also be manifested in the other body systems. The respiratory, cardiovascular, gastrointestinal, and genitourinary tracts as well as the musculoskeletal and integumentary systems should be assessed accordingly. The findings may assist in determining the level of spinal involvement, guide diagnostic testing for the myelitis, and help rule out other diagnoses.

Functional Limitations

The physiatrist is likely to encounter the patient as a consultation or referral for rehabilitation assessment and management or for specific problems, such as spasticity and pain intervention. As with other spinal cord injuries, the functional limitations in transverse myelitis usually depend on the level or levels of injury and the muscles that are affected or continue to be innervated normally. Debilitation and deconditioning from associated illnesses and prolonged recumbence will also affect function secondarily.

Recovery is often related to the clinical presentation and may or may not be complete. In general, one third of patients with acute transverse myelitis make a good recovery, another third have fair recovery, and the rest either fail to improve or die [5,7,10,16]. In idiopathic transverse myelitis treated with methylprednisolone, by use of the Medical Research Council (MRC) scale for muscle strength (5, normal; 0, no movement is observed), 37.5% were reported to have complete recovery or minimal residual deficit (MRC 5-4), 43% had partial recovery (MRC 3), and 19.4% had severe disability or absent recovery (MRC 0-2). Factors associated with poor outcomes include severe initial symptoms with spinal shock, delayed presentation to the hospital after maximum deficits have already occurred, development of syringomyelia, and extensive MRI lesions [5,10]. If no recovery has occurred by 1 to 3 months, complete recovery is less likely [3,12].

The following functional capability review according to spinal level may be influenced by whether the cord injury is unilateral or bilateral and the degree of completeness. A patient with only C4 innervation preserved and loss of function distally may or may not have respiratory difficulties but will be dependent for most self-care activities. Using appropriate technology and devices, whether they are customized or commercially available, the patient may be able to control the immediate home environment, summon assistance, and mobilize in an electric wheelchair with a chin control or a sip-and-puff interface. Devices that can be controlled by moving and positioning the head, cheek, or tongue and by infrared-sensitive or voice-activated mechanisms include door openers and various electronic devices such as the television and personal computer.

A patient with C5 level may be able to self-feed and groom with equipment such as a glove with universal cuff allowing attachment of tools (e.g., fork, spoon, or comb). The patient can independently use a powered wheelchair and propel a lightweight manual wheelchair with rim projections (“quad knobs”) for limited distances over level ground. C6 innervation allows independence with upper extremity dressing, bathing with equipment, and functional use of a manual wheelchair indoors. The patient with superior balance and motor control could potentially perform independent or supervised transfers with a sliding board, self-catheterize with appropriate aids, and drive a specially adapted automatic transmission vehicle with powered steering, hand-controlled accelerator and brake. A C7 level allows independence in all self-care activities with equipment and independent transfers because of preserved ability to push off with the elbow extensors, and the patient may be able to live alone. A patient with C8 and T1 innervation will have improved manual dexterity and strength for self-care, is independent with a manual wheelchair, and should be able to self-catheterize.

The patient with preservation of upper thoracic innervation has a degree of trunk control that increases stability during use and propulsion of a manual wheelchair. It also adds to ease and independence with bladder and bowel self-management. With bracing of the hips, knees, and ankles (knee-ankle-foot orthoses), minimal ambulation can be attempted, although this would be more for encouragement and exercise purposes than truly functional. Independent ambulation even with bracing and bilateral axillary or forearm crutches is usually not realistic unless the patient has preservation of some upper lumbar innervation. Further preservation of lumbar and sacral innervation will increase ease of ambulation with better trunk and pelvic control. There have been developments in exoskeleton systems to assist standing and ambulation, such as the ReWalk (Argo Medical Technologies Inc., Marlborough, Mass) and Ekso (Ekso Bionics, Richmond, Calif), although these are currently still limited by the individual patient’s abilities, terrain, and need for safety supervision. The patient with incomplete spinal injury is less predictable, and functional abilities will largely depend on the degree and nature of neurologic preservation.

Diagnostic Studies

With increasingly greater resolution, T1 versus T2 weighting, and other techniques to enhance and to suppress the appearance of tissues of different densities, the best tool when transverse myelitis is suspected is MRI. MRI not only allows visualization of the lesion but also helps rule out potentially treatable causes, such as tumor, abscess, and other lesions causing compressive myelopathy. Contrast material can be given to highlight lesions [17], and myelography may be considered if MRI is not available.

Although it is not definitive, there are MRI features that help differentiate transverse myelitis from other disorders, such as multiple sclerosis (Figs. 161.1 and 161.2). Transverse myelitis is more likely to have high signal intensity on T2-weighted images extending longitudinally over more segments [17,18]. The number of segments involved may be 1 or 2, to as many as 11. The entire cord or sometimes only the medulla may be affected [17–20]. In transverse myelitis, the lesion appears more likely to affect the central region of the cord and to involve more than two thirds of the cord diameter.

In multiple sclerosis, the lesion appears more peripheral and generally involves less than half of the diameter of the cord [17