26th June 2023

Cauda Equina syndrome and Conus Medullaris syndromes

Both syndromes are relatively uncommon and approached very similarly in the practical day-to-day work on a medical unit, i.e. if suspected, a digital rectal examination, sensory body map of the lower limbs to both touch and pinprick, pre-void and post-void bladder scan should be performed and MRI imaging with neurosurgical referral made, as both are neurosurgical emergencies that warrant emergent surgical intervention.

Conus Medullaris syndrome is the result of a lesion to, or of, the spinal cord itself at the conus medullaris (termination of spinal cord at L1-L2), and hence presents with bilateral symmetrical signs and is usually due to spinal cord intrinsic lesions, e.g. intrinsic tumours such as ependymomas or astrocytomas, spinal cord metastases, sarcoidosis, and demyelinating lesions.

Cauda Equina syndrome results from a lesion to the nerve roots that make up the cauda equina and is usually caused by compression from intervertebral disc herniation or trauma, with other causes being epidural lesions, e.g. epidural metastases and abscesses, leptomeningeal carcinomatosis, schwannoma of the nerve roots, and rarely inflammatory causes, e.g. arachnoiditis, cytomegalovirus polyradiculitis.

Clinical features

Spinal Cord Compression

A spinal cord compression can be due to a large variety of traumatic and atraumatic causes similar to Cauda Equina and Conus Medullaris syndromes. Traumatic causes include intervertebral disc herniation and compression from vertebral fractures, while atraumatic causes include degenerative spondylosis with resulting myelopathy, spinal epidural abscesses or haematomas, and primary and metastatic spinal cord tumours. A spinal cord compression is a medical emergency, and suspicion should prompt an urgent MRI scan and treatment with urgent glucocorticoids, typically dexamethasone which downregulates vascular endothelial growth factor and prostaglandin E2, decreasing spinal cord oedema. Prompt referral to neurosurgery, and if indicated, oncology teams for rescue radiotherapy should be considered.