Conus medullaris syndrome

Background

  • The conus medularis (tapered end of the spinal cord) is proximal to the cauda equina.[1]

Epidural compression syndromes

Clinical Features

Epidural compression syndromes table[2]

Syndrome Spinal cord compression Conus medullaris syndrome Cauda equina syndrome
Location of lesionLesions at vertebral level L2
Spontaneous painUnusual and not severe; bilateral and symmetrical in perineum or thighsOften very prominent and severe, asymmetrical, radicular
Motor findingsDeficits usually affect both legs but are often asymmetricNot severe, symmetrical; rarely twitchesMay be severe, asymmetrical, fibrillary twitches of paralyzed muscles are common
Sensory findingsWeakness in lower extremities, paresthesias/sensory deficits, gait difficultySaddle distribution, bilateral, symmetrical, disassociated sensory loss (impaired pain and temperature with sparing of tactile)Saddle distribution (75% pts), may be asymmetrical, no dissociation of sensory loss
Reflex changesAchilles reflex may be absentPatellar and Achilles reflexes may be absent
Sphincter disturbanceBladder and rectal sphincter paralysis usually reflect involvement of S3-S5 nerve rootsEarly and marked (both urinary and fecal)Late and less severe (60-80% pts)
Male sexual functionImpaired earlyImpairment less severe
OnsetSudden and bilateralGradual and unilateral
OtherUrinary retention with or without overflow incontinence (Sn 90%, Sp 95%)

Differential Diagnosis

Lower Back Pain

Spinal Cord Syndromes

Evaluation

  • Emergent MRI
    • If considering compression due to neoplasm obtain scan of entire spine
  • Consider Bladder scan/ultrasound for bladder volume (post-void residual)

Management

General Epidural Compression Syndrome Management

  • Dexamethasone: at least 16 mg IV as soon as possible after assessment[3]
    • Note: dexamethasone can be used to reduce compressive edema from epidural metastases, but is more likely to worsen an infection from spinal epidural abscess.
  • Consult spine service
  • Consider foley for bladder decompression

Disposition

  • Admit

See Also

References

  1. Cohen MS, Wall EJ, Kerber CW, et al. The Anatomy of the Cauda Equina on CT Scans and MRI. J Bone Joint Surg Br 1991; 73 (3): 381-84.
  2. Bradley WG. Neurology in Clinical Practice: Principles of diagnosis and management. P363
  3. Metastatic spinal cord compression: Diagnosis and management of patients at risk of or with metastatic spinal cord compression. Full Guideline. November 2008. Developed for NICE by the National Collaborating Centre for Cancer. ©2008 National Collaborating Centre for Cancer
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