• Clinical science

Incomplete spinal cord syndromes

Abstract

Incomplete spinal cord syndromes are caused by lesions of the ascending or descending spinal tracts that result from trauma, spinal compression, or occlusion of spinal arteries. Central cord syndrome, anterior cord syndrome, posterior cord syndrome, and Brown-Séquard syndrome are the most common types of incomplete spinal cord syndromes. In contrast to a complete spinal cord injury, lesions only affect part of the cord and patients present with a dissociated sensory loss. A spine MRI is the diagnostic modality of choice to determine the etiology, level, and extent of the lesion. Treatment depends on the underlying etiology. In some cases, surgery may be necessary to treat the underlying cause and to improve the patient's outcome. Spinal compression is a medical emergency and requires urgent treatment with steroids and decompressive surgery.

Overview

Basic neuroanatomy and function

  1. Pyramidal tracts (lateral corticospinal tract and anterior corticospinal tract)
    • Descending tracts originate in the cerebral cortex and extend to the alpha (α) motor neuron in the ventral horn of the spinal cord.
    • About 90% of pyramidal neurons decussate as they pass through the medulla and descend further as the lateral corticospinal tract.
    • The remaining 10% continue as the anterior corticospinal tract and decussate at the segmental level.
    • Function: controls motor function
  2. Posterior column (posterior funiculus consisting of gracile and cuneate fasciculi)
  3. Spinothalamic tract (anterior spinothalamic tract and lateral spinothalamic tract)
    • Decussation only at segmental level or shortly above
    • Function: : conveys protopathic sensation: contralateral temperature, pain stimuli, and crude touch

Types of incomplete spinal cord syndromes

  • All types present with dissociated sensory loss: a pattern of selective sensory loss (“dissociation of modalities”); suggests a focal lesion of a single tract within the spinal cord (or brainstem)
Affected spinal tracts Etiology Clinical features
Central cord syndrome (most common)
  • Bilateral paresis: upper > lower extremities
Anterior cord syndrome
  • Corticospinal and spinothalamic tracts
  • Trauma (e.g., penetrating injury, burst fracture of vertebra)
  • Occlusion of anterior spinal artery
  • Bilateral motor paralysis, loss of pain and temperature sensation, and autonomic dysfunction below the level of the lesion
Posterior cord syndrome
  • Trauma (e.g., penetrating injury)
  • Occlusion of the posterior spinal artery
  • Multiple sclerosis
  • Ipsilateral loss of proprioception, vibration, and touch sensation below the level of the lesion
Brown-Séquard syndrome (hemisection syndrome)
  • Hemisection of the cord

Spinal arteriovenous malformation

  • Definition: congenital malformation of spinal blood vessels
  • Epidemiology: usually presents in younger patients (mid-20s)
  • Pathophysiology: abnormal arteriovenous connections of spinal arteries to veins within the dura (intramedullary, mostly thoracic or lumbar) → arterialization of spinal veins → congestive myelopathy because of venous hypertension, stasis, and multi-segmental spinal cord lesions → mass effect and/or ischemia and/or hemorrhage into the cord
  • Clinical features
  • Diagnostics
    • MRI: cluster of low-intensity signal foci
    • Spinal digital subtraction angiography (DSA)
  • Therapy: possibly endovascular embolization/occlusion or surgical resection (depends on type and localization)
  • Complication: tetraplegia with motor and sensory loss

References:[1][2][3][4][5][6][7][8][9][10]

Central cord syndrome

  • Definition: injury to the central region of the spinal cord (central corticospinal tracts and decussating fibers of the lateral spinothalamic tract)
  • Epidemiology:
    • Most common type of incomplete cord syndrome
    • Common in the elderly with preexisting degenerative changes in the cervical spine
  • Etiology: syringomyelia, degenerative spine disease, cervical spondylosis, traumatic disc herniation, various hyperextension injuries (e.g., car crash → whiplash injury in a person with long-standing cervical spondylosis)
  • Clinical features
    • Bilateral motor paresis (upper > lower extremities; distally > proximally)
    • Variable sensory impairment
      • Sometimes burning pain in the arms
      • Sometimes loss of pain and temperature in the arms
  • Diagnostics: CT and/or MRI to determine location, cause, and extent of neurological damage
  • Therapy: see management of spinal cord injuries
  • Prognosis: relatively good prognosis

References:[11][12]

Anterior cord syndrome

  • Definition: damage to the anterior two-thirds of the spinal cord usually as a result of reduced blood flow or occlusion to the anterior spinal artery (ASA) Anterior spinal artery syndrome (∼ 95% of cases)
  • Etiology
    • Arteriosclerosis, vasculitis (e.g., associated with diabetes or syphillis), thrombosis, embolic occlusion
    • Aortic dissection, aneurysm
    • Trauma (e.g., penetrating injury, burst fracture, hyperflexion injury with vertebral instability which is common in young athletes)
    • Iatrogenic (e.g., during aortic surgery, spinal angiography, or spinal anesthesia))
    • Severe hypotension (e.g., following hemorrhage)
    • Pathological compression (e.g., tumors, cervical spondylosis)
  • Clinical features
  • Special variant: Lesion of the artery of Adamkiewicz
    • Etiology: : same etiologies as mentioned above (especially aortic repairs) → reduced blood flow or occlusion of the artery of Adamkiewicz
    • Clinical features: features of ASA syndrome
  • Diagnostics
    • Spinal MRI (best confirmatory test): excludes soft-tissue lesions (e.g., tumors, hematomas), bone lesions, and detects spinal cord parenchyma abnormalities (e.g., infarction)
    • Consider VDRL or RPR if syphilis is suspected
  • Therapy
  • Prognosis: 10–15% functional recovery; if no recovery is evident and progressive after 24 hours, prognosis is poor

Vibration and proprioception are typically spared because of an intact dorsal column!

References:[11][13][14][15][16][17][18]

Posterior cord syndrome

  • Definition: injury of the posterior spinal cord affecting the posterior column (fine touch, vibration, pressure, and proprioception)
  • Epidemiology: very rare
  • Etiology: occlusion of the posterior spinal artery , multiple sclerosis
  • Clinical features: ipsilateral loss of vibration and proprioceptive sensation below the lesion
  • Diagnostics: MRI showing infarction of the dorsal columns in the case of posterior spinal artery occlusion
  • Therapy: see management of spinal cord injuries
  • Prognosis: patients show functional gain with rehabilitation

References:[19][20][21][22]

Brown-Séquard syndrome

Autonomic symptoms are generally absent because of unilateral involvement of the descending autonomic fibers.

References:[11][4][23]