Pathophysiology and surgical decision-making in central cord syndrome and degenerative cervical myelopathy: correcting the somatotopic fallacy

Abstract

Our understanding of Central Cord Syndrome (CCS), a form of incomplete spinal cord injury characterized by disproportionate upper extremity weakness, is evolving. Recent advances challenge the traditional somatotopic model of corticospinal tract organization within the spinal cord, suggesting that CCS is likely a diffuse injury rather than focal lesion. Diagnostic criteria for CCS lack consensus, and varied definitions impact patient identification and treatment. Evidence has mounted for early surgery for CCS, although significant variability persists in surgical timing preferences among practitioners. A demographic shift toward an aging population has increased the overlap between CCS and Degenerative Cervical Myelopathy (DCM). Understanding this intersection is crucial for comprehensive patient care. Assessment tools, including quantitative measures and objective evaluations, aid in distinguishing CCS from DCM. The treatment landscape for CCS in the context of pre-existing DCM is complex, requiring careful consideration of pre-existing neurologic injury, patient factors, and injury factors. This review synthesizes emerging evidence, outlines current guidelines in diagnosis and management, and emphasizes the need for ongoing research to refine our understanding and treatment strategies for this evolving patient population.

Keywords: central cord syndrome; cervical spine; clinical outcome; myelopathy; neurosurgery; operative management; spinal cord injury; surgical intervention.

Figure 1

Re-appraisal of pathophysiology of central cord syndrome (CCS) with error of historic models of somatotopic organization in the spinal cord. (A) Central cord syndrome as classically described in 1954 by Schneider et al. as traumatic hyper-extension in a stenotic cervical spinal column leading to an incomplete spinal cord injury affecting the upper more than the lower extremities (6). (B) The prevailing theory for the pathophysiology of CCS, until recently, was that the cortical spinal tract (CST) has a lamellar organization in the cervical spinal cord with the upper extremity axons coursing in the most mesial portion, thereby leading to greater injury of the descending control of the arm and hand, and preservation of the leg. This theory was propagated in most—if not all—major texts of anatomy and neurology until recently, including this image from Gray's Anatomy (41^st Ed, 2016). (C–E) This long-held hypothesis of CST somatotopy has been shown inaccurate by careful work in non-human primates. (C) The CST fibers serving the upper extremity and lower extremity course throughout the cross-sectional area of the tract. (D) Quantification of axon density shows no difference in mesial to lateral sections. (E) A recent model from Lemon and Morecraft (7) demonstrates a complete lack of somatotopic organization with random dispersion of CST axons in the cervical enlargement in primates. C5, 5^th cervical level; CCS, central cord syndrome; CST, corticospinal tract; M1, primary motor cortex; ns, not significant. (A) This figure is protected by Copyright, is owned by The JNS Publishing Group, and is used with permission only within this document. Permission to use it otherwise must be secured from The JNS Publishing Group. Full text of the article containing the original figure is available at thejns.org. (C–E) © 2022 The authors, CC BY-NC-ND 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/); (F) © 2022 Roberto Suazo.

Figure 2

Illustrative case study of Central Cord Syndrome (CCS) on pre-existing Degenerative Cervical Myelopathy (DCM): evaluating best patient selection in elective and emergent settings. Patient selection for elective decompression of DCM and emergent decompression of CCS can prove difficult. (i) While both previously healthy, Patient A is a healthy 74-year-old-male who has not received decompression for his moderate DCM (mJOA 14), while Patient B is a healthy 71 year-old-female who was offered a two-level ACDF for mild DCM (mJOA 16). (ii) Following falls, both these patients presented with CCS that included significant weakness and sensory changes. Patient A had a C5 level ASIA C grade injury, with inability to move his arms and hands against gravity. Patient B had a C4 level ASIA D grade injury, with ability to move her arms and hand against gravity but without meaningful strength. (iii) Each patient had a successful decompression of their cervical compression; however, Patient A was delayed in receiving surgery due to inadequate identification of spinal cord injury and consultation to a specialized Spine Surgeon. Patient B had emergent surgery in less than 24 h. Based on current evidence, we suggest that—while both patients are candidates—Patient A may have a greater predictive benefit from elective decompression of chronic moderate DCM, as well as emergent (< 24 h) surgical decompression of acute traumatic AIS C grade CCS. #, fracture; ACDF, anterior cervical decompression and fusion; ASD, adjacent segment disease; ASIA, American Spinal Cord Injury Association Impairment Scale; C4/5, 4/5^th cervical level; CCS, central cord syndrome; DCM, degenerative cervical myelopathy; mJOA, modified Japanese Orthopedic Association scale; PM/SHx, past medical and surgical history; PSF, posterior spinal decompression and fusion; UEMS/LEMS, Upper/Lower Extremity Motor Score.