Surgical Treatment Modalities for Cervical Stenosis: Central Cord Syndrome and Other Spinal Cord Injuries in the Elderly

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27 Surgical Treatment Modalities for Cervical Stenosis: Central Cord Syndrome and Other Spinal Cord Injuries in the Elderly

Michael Fehlings, Randolph Gray

KEY POINTS

• Central cord syndrome occurs more often in the elderly population.

• The pathophysiology of spinal cord injury involves a primary mechanical insult, followed by secondary injury that is multifactorial, though triggered by ischemia.

• Cord deformation and signal change are commonly seen in patients with central cord syndrome.

• There is currently no standard regarding the timing of surgery in patients with central cord syndrome.

• If surgery is elected, evidence suggests that surgery can be performed safely within the first 24 hours, which may positively influence neurological outcomes.

Acute central cord syndrome was first described in 1954 by Schneider, in a case series of 8 patients with neurological deficits following hyperextension injury to the cervical spine and a review of another 6 cases reported in the literature with a similar injury mechanism and neurological presentation. ¹

The leading causes of SCI are motor vehicle accidents, sports and recreational activities, accidents at work, falls in the home, and violence.

It is estimated that the annual incidence of SCI varies between 11.5 to 53.4 per million population.² In the United States, the annual incidence is around 40 per million. Central cord syndrome is the most common spinal cord injury pattern.³ The relative distribution of other types of SCI is shown in Figure 27-1.

Figure 27-1 The relative distribution of syndromes in spinal cord injury. BSS, Brown-Séquard syndrome; CMS, Conus medullaris syndrome; ACS, Anterior cord syndrome; PCS, Posterior cord syndrome; CCS, Central cord syndrome; CES, Cauda equina syndrome.

Mechanism

Based on radiographic, operative, and postmortem findings, Schneider postulated that during forceful hyperextension the anterior osteophytes and the bulging of the ligamentum flavum caused significant anteroposterior narrowing of the spinal canal and contusion of the spinal cord (Figure 27-2). He noted in the postmortem findings that the maximum injury was in the central part of the spinal cord. The mechanism of central cord syndrome is a hyperextension injury, often on a background of long-standing cervical spondylosis, with no bony or ligamentous injury. Hyperextension of the cervical spine causes overlapping of the laminae and buckling of the ligamentum flavum, reducing the canal diameter by a further 2 to 3 mm. This compromise may cause significant acute cord compression in an aging spondylotic cervical spine with preexisting discoligamentous and osseous compression. It is estimated that this mechanism of hyperextension accounts for around 50% of cases of acute traumatic central cord syndrome (ATCCS). The other mechanisms are fractures and/or subluxations and herniated nucleus pulposus.⁴ The most common mechanism of injury in the elderly population is a low-energy ground-level fall with impact on the head or chin causing forceful hyperextension of the neck. Typically this low-energy impact does not cause any bony injury.

Figure 27-2 Original drawing of the hyperextension mechanism from Schneider’s paper in 1954.

(From Schneider RC, Cherry G, Pantek H: The syndrome of acute central cervical spinal cord injury; with special reference to the mechanisms involved in hyperextension injuries of cervical spine [part 1], J Neurosurg 11:546-577, 1954.)

Definition of Central Cord Syndrome

Central cord syndrome was described by Schneider in 1954: ‘‘It is characterized by disproportionately more motor impairment of the upper than the lower extremities, bladder dysfunction, usually urinary retention, and varying degrees of sensory loss below the level of the lesion.’’ (Box 27-2).¹

Box 27-2

• Acute cervical spinal cord injury caused by traumatic forceful hyperextension of the neck

• Disproportionate motor impairment of upper more than lower extremities

• Bladder dysfunction and urinary retention

• Varying degrees of sensory loss below the level of the lesion

• Recovery pattern is characterized by the return of lower extremity function first, followed by upper limb function, with finger movement being the last of the upper limb functions to return.

Incidence and Age

The average age of spinal cord injury (SCI) has increased from 28.7 to 38 years, and the percentage of spinal cord injury in people over 60 years of age has increased from 4.7% to 11.5%. After the age of 45 years, falls are the most common cause of cervical spinal cord injury, increasing in incidence with advancing age. In one series, 74% of injuries in patients 70 years of age or older were caused by falls (Figure 27-3).⁵ SCI in the elderly typically results from a low-energy injury sustained from a fall at ground level. There is a bimodal pattern of the age distribution in ATCCS patients. The increase in age has had an impact on the pathogenesis, functional deficit, recovery, and rehabilitation of patients with spinal cord injuries.⁶ In general, older patients demonstrate less recovery from spinal cord injury compared to younger patients (Box 27-3).⁷ Experimental animal studies have shown that increased age increases the area of pathology and amount of demyelination, while demonstrating a significantly lower amount of endogenous remyelination following induced SCI.⁶ These studies have demonstrated that abnormalities in myelination and functional deficits secondary to SCI are age-related.