Cauda Equina Syndrome

This article is a stub.

Cauda equina syndrome can be caused by a lesion in the spinal canal at any level below T10. The cauda equina includes the terminal spinal cord, all of the T12-S5 spinal roots, and the filum terminale. The filum terminale is a fibrous band that extends from the tip of the cord and attaches to the sacrum.^[1]

Clinical Pictures

There are three main clinical pictures of Cauda Equina lesions in adults. In children, disc lesions are exceptionally rare below 15 years of age.^[1]

Lateral Cauda Equina Syndrome

Neurofibroma is the most frequent cause, and high disc lesions are a rarer cause. The clinical features include anterior thigh pain, quadriceps wasting, weakness of foot inversion (L4 root lesion), and an absent knee jerk. With very high lesions that lie lateral to the terminal spinal cord, there may be pyramidal signs below the lesion. In this case there may be very brisk ankle jerks, ankle clonus, and an extensor plantar response. In this context, any sphincter compromise is likely a result of the cord compression.^[1]

Midline Cauda Equina Lesions from Within

This is also called a conus lesion. The most common causes are ependymomas, dermoid tumours, and lipomas of the terminal cord. The roots are damaged from the inside, that is from S5 to S4 to S3 etc. In the early stages clinical features include rectal and genital pain, urination problems, and erectile dysfunction, but with no clear physical signs except if the perianal sensation (saddle anaesthesia) and anal reflex are tested carefully. Later clinical features include reduced ankle jerks and weakness of L5 and S1 myotomes. For ependymomas, the patient may have a 5 year history of a dull backache.^[1]

Midline Cauda Equina Lesions From Outside

This is characterised by bilateral lumbar and sacral root lesions. If the patient has pain in unusual dermatomes such as L2, L3, S2, or S3, then the clinician should be suspicious. Pain in an L4, L5, or S1 region on the other hand is usually due to disc disease, but further imaging may still be required to exclude other pathology. The causes include primary sacral bone tumours (chordomas), metastatic disease (especially prostate), reticulosis, leukaemia, direct seeding from malignant tumours in the CNS (medulloblastomas, ependymomas, pinealomas).^[1]

↑ ^1.0 ^1.1 ^1.2 ^1.3 ^1.4 Patten, John. Neurological differential diagnosis. London New York: Springer, 1996.

[patten-1] 1.0 ^1.1 ^1.2 ^1.3 ^1.4 Patten, John. Neurological differential diagnosis. London New York: Springer, 1996.

[1]