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How Do I Diagnose and Manage SCIWORA?

Jack E. Wilberger

BRIEF ANSWER

Background

The term SCIWORA was coined in 1982 by Pang and Wilber ger¹ to describe the entity of traumatic myelopathy in the absence of any abnormality on plain spine x-rays, flexion/extension radiographs, CT, or myelography. Since the introduction of MRI, SCIWORA has become a misnomer because only rarely is MRI normal in such situations. Nevertheless, SCIWORA is a distinct clinical entity in the spectrum of spinal cord injury (SCI) and warrants elucidation of its presentation, pathophysiology, and treatment.

Literature Review

A Medline search of the literature from 1980 to 2001 was conducted with the following key words: SCIWORA, Spinal Cord Injury Without Radiographic Abnormality, and MRI in Spinal Cord Injury. One hundred twenty-two articles were found. All represented case reports, retrospective studies, and reviews; that is, only class III data were available for review. Only articles from which specific patient information could be gleaned were reviewed.

A total of 364 cases were identified, with all but 15 occurring in individuals over 15 years of age.^2–14 The cervical spine was affected more than twice as frequently as the thoracolumbar spine: 68% versus 32%, respectively.

Even though pediatric spinal cord injury is a rare entity that makes up no more than 10 to 12% of all spinal cord injury,¹⁵ SCIWORA is the most common cause of pediatric SCI; up to 60% of such cases may fall into the category of SCIWORA.^16,17

Age was a significant determinant not only of location but also of injury severity. Virtually all reported cases of SCIWORA involving the upper cervical spine occurred in children under 8 years of age, as did the most severe neurologic syndromes and sequelae.1,12,13

Pathophysiology

The suspected pathophysiology of SCIWORA as first postulated by Pang and Wilberger has not been challenged. These injuries are thought to occur as a result of flexion, hyperextension, longitudinal distraction, and ischemia.

The pediatric population is particularly susceptible to excessive flexion and hyperextension because of the inherent ligamentous laxity of this age group and because of the more horizontal orientation of the cervical facet joints, which permits excessive translational movement.^3,18 In addition, the relatively larger size of the head in relation to the weak cervical musculature predisposes the cervical spine to undergo a fulcrum-like movement. With extreme hyperextension, the spinal canal can narrow by up to 50% because of buckling of the ligamentum flavum, with possible transient obstruction of one or both vertebral arteries.³

Longitudinal distraction occurs most commonly in neonatal injuries. Once again, because of ligamentous laxity, the spine can “stretch” up to 2 inches without suffering apparent damage. Spinal cord disruption, however, occurs after approximately –1/4-inch of distraction.¹⁹

In the few adult cases reported, 50% were thought to be due to a concussive injury to the bone, with subsequent transmission to the spinal cord.²⁰

The literature contains 29 reported cases of SCIWORA due to traumatic disk herniations. In each case, the patient returned to normal neurologic function after treatment. Also, Bondurant and Oro⁴ suggested an association between Arnold-Chiari malformation type I and SCIWORA in four children.

Clinical Presentation

Virtually all reported SCIWORA cases describe a transient, often nonspecific neurologic syndrome followed within hours to days by the onset of more severe symptoms, up to and including quadriplegia. In most instances, no “secondary injury” could be identified.^1,12,13 The reported incidence of this type of delayed onset of SCIWORA varies, exceeding 50% in some series.^1,6,12–14 Although the underlying mechanism is far from clear, it is suspected that the pathophysiologic factors previously described play a significant role in making the spine/spinal cord more susceptible to a seemingly trivial and perhaps unperceived second insult, which precipitates the ultimate neurologic manifestations.

Pollack et al¹³ studied a further variation of the delayed presentation of SCIWORA. Eight children suffered further neurologic injury in spite of 2 months of immobilization with collars and restrictions on activity. There was a clear inciting traumatic incident in seven of the eight children and, in many cases, activity limitations were ignored and collars were discarded. This, however, suggests that healing of the spinal ligamentous injuries may be prolonged, even in a young population.

Magnetic Resonance Imaging in SCIWORA

MRI findings have been reported in 45 reported cases of SCIWORA (15 adults and 30 children).^2,20–22 The incidence of MRI abnormalities appears to be greater in adults (14 out of 15) than in children (19 out of 30).

Grabb and Pang²² reviewed MRIs in seven children with SCIWORA and found no extraaxial compressive lesions. They concluded that MRI in SCIWORA “probably influences its acute management infrequently.” However, these same authors did identify two significant ligamentous injuries on MRIs in this small series of patients.

SCIWORA Management

Virtually all authors on this subject recommend a complete workup in any child presenting with transient neurologic deficits after suspected spine trauma. This workup includes adequate spine x-rays, CT scans of any inadequately visualized area or any area that is suspicious for injury, and flexion/extension views. It must be recognized, however, that “normal” flexion/extension films may not rule out SCIWORA because, when muscle spasm is present, suboptimal studies may be obtained. Additionally, flexion/extension films are generally accomplished in a gentle fashion in a supervised setting, which in no way simulates real-life situations. MRI is indicated if all of the above studies are normal. SEPs may be useful in documenting and following any subclinical electrophysiologic spinal cord dysfunction.