Cauda Equina Syndrome

Question 1

Cauda equina syndrome is due to compression of the collection of nerves distal to the terminal part of the spinal cord known as the cauda equina.

Answer 1

Cauda equina syndrome is due to compression of the collection of nerves distal to the terminal part of the spinal cord known as the cauda equina.

Question 2

The cauda equina, which is Latin for ‘horses tail’, refers to the collection of spinal nerves that lie within the subarachnoid space distal to the last part of the spinal cord known as the … medullaris. Compression of the cauda equina leads to a syndrome characterised by lower limb weakness, bladder and bowel dysfunction, and abnormal perianal sensation. It is considered a neurosurgical emergency.

Answer 2

The cauda equina, which is Latin for ‘horses tail’, refers to the collection of spinal nerves that lie within the subarachnoid space distal to the last part of the spinal cord known as the conus medullaris. Compression of the cauda equina leads to a syndrome characterised by lower limb weakness, bladder and bowel dysfunction, and abnormal perianal sensation. It is considered a neurosurgical emergency.

Question 3

The spinal cord originates at the base of the medulla oblongata, exiting the skull through the … …. It then extends through the spinal canal and ends at the level of the L1/L2 spinal vertebrae.

Answer 3

The spinal cord originates at the base of the medulla oblongata, exiting the skull through the foramen magnum. It then extends through the spinal canal and ends at the level of the L1/L2 spinal vertebrae.

Question 4

The spinal cord is part of the central nervous system (CNS) and forms the main communication between the brain and peripheral nerves.

Answer 4

The spinal cord originates at the base of the medulla oblongata, exiting the skull through the foramen magnum. It then extends through the spinal canal and ends at the level of the L1/L2 spinal vertebrae.

It is divided into four main regions termed cervical, thoracic, lumbar, and sacral. This is further divided into 31 spinal cord segments. Arising from the 31 spinal cord segments are the paired ventral and dorsal spinal nerve roots, which join to form the 31 paired spinal nerves.

Question 5

Label

Answer 5

Question 6

The terminal end of the spinal cord is termed the … …

Answer 6

The terminal end of the spinal cord is termed the conus medullaris

Beyond this is a collection of spinal nerves composed of lumbar, sacral, and coccygeal nerves. Together these make up the cauda equina. These nerves have important innervation for lower extremity motor function, perianal sensation, and parasympathetic sensation to the bladder and bowel including the sphincters.

Question 7

The terminal end of the spinal cord is termed the conus medullaris

Beyond this is a collection of spinal nerves composed of lumbar, sacral, and coccygeal nerves.

Together these make up the cauda equina. These nerves have important innervation for lower extremity motor function, … sensation, and parasympathetic sensation to the … and bowel including the ….

Answer 7

The terminal end of the spinal cord is termed the conus medullaris

Beyond this is a collection of spinal nerves composed of lumbar, sacral, and coccygeal nerves. Together these make up the cauda equina. These nerves have important innervation for lower extremity motor function, perianal sensation, and parasympathetic sensation to the bladder and bowel including the sphincters.

Question 8

Epidemiology

Cauda equina

Answer 8

Cauda equina syndrome is a rare condition.

Question 9

Cauda equina syndrome has a … global incidence

Answer 9

Cauda equina syndrome has a low global incidence with no large data reporting the prevalence of the condition. It is estimated to account for 2-6% of lumbar disc operations and a UK GP may go their entire career without seeing a complete case.

Question 10

Any … of the spinal canal at the level of the cauda equina can give rise to the syndrome.

Answer 10

Any narrowing of the spinal canal at the level of the cauda equina can give rise to the syndrome.

Question 11

Cauda equina syndrome may be caused by a variety of pathologies that lead to narrowing of the spinal canal from L1/2 downwards. This narrowing leads to compression of several, or many, of the nerves contained within the cauda equina.

Common causes include: (6)

Answer 11

Lumbar stenosis: narrowing of the spinal canal in the lumbar region
Spinal trauma
Disc disease: herniation of the disc
Malignancy: primary tumour of the nervous system or metastasis
Spinal infections: abscess, tuberculosis
Neural tube defects (e.g. spinal Bifida)

Question 12

The cauda equina contains nerves that exit from the spinal cord and form part of the peripheral nervous system. Therefore, patients usually have features of …

Answer 12

The cauda equina contains nerves that exit from the spinal cord and form part of the peripheral nervous system. Therefore, patients usually have features of a lower motor neuron weakness (i.e. low tone, weakness, hyporeflexia, downing plantars). Patients with a lesion of the spinal cord have evidence of upper motor neuron weakness (i.e. high tone, weakness, hyperreflexia, upgoing plantars).

Question 13

Cauda equina syndrome is characterised by … (4)

Answer 13

Cauda equina syndrome is characterised by low back pain, leg weakness, saddle anaesthesia, and bladder/bowel dysfunction.

Question 14

When should cauda equina be suspected?

Answer 14

It should always be suspected in low back pain and new-onset neurological deficits. Asymmetrical, bilateral sciatica-like pain (shooting pain due to irritation of lumbosacral nerve roots) with new neurological deficits in the lower limb and bladder/bowel dysfunction is classic.

Question 15

Symptoms of cauda equina syndrome

Answer 15

Low back pain
Asymmetrical sciatica pain
Saddle anaesthesia: reduced or absent sensation around the perineal skin
Bladder dysfunction: urinary retention, difficulty passing urine, overflow incontinence
Bowel dysfunction: constipation, incontinence, loss of anal tone
Lower limb weakness: often asymmetrical

Question 16

Signs of cauda equina syndrome

Answer 16

Hypotonia
Leg weakness
Hyporeflexia
Leg sensory changes: may have abnormal sensation along a single dermatome
Reduced sensation around perianal area
Loss of anal tone (on PR examination)
Palpable bladder

Question 17

Differential diagnosis

It is important to differentiate between three conditions that all lead to back pain and neurological deficits.
What are the three?

Answer 17

Cauda equina: compression of the lumbosarcal nerve roots that make up the cauda equina. These are peripheral nerves and therefore compression causes a lower motor neuron pattern of weakness.
Conus medullaris: compression of the last part of the spinal cord at L1/L2. Compression at the conus causes a clinical picture similar to cauda equina but with mixed neurological signs (upper and lower motor neuron features) as it also affects part of the cord.
Cord compression: compression of the spinal cord at any level within the cervical, thoracic or lumbar region. Following the acute insult, this causes a classical upper motor neuron pattern of weakness.

Question 18

NOTE: acute … usually causes flaccid paralysis (i.e. low tone and hyporeflexia). Over time, the pattern of weakness classically becomes upper motor neuron with features of high tone and hyperreflexia.

Answer 18

NOTE: acute cord compression usually causes flaccid paralysis (i.e. low tone and hyporeflexia). Over time, the pattern of weakness classically becomes upper motor neuron with features of high tone and hyperreflexia.

Question 19

The key differences between spinal cord compression, conus medullaris syndrome and cauda equina syndrome are shown in the table below:

Answer 19

Question 20

The principal investigation for the diagnosis of suspected cauda equina is an …

Answer 20

The principal investigation for the diagnosis of suspected cauda equina is an MRI spine.

Question 21

Diagnosis & investigations

Cauda equina

Answer 21

Patients with suspected cauda equina should be referred urgently to accident and emergency for assessment and imaging of the spine. The reliability of a clinical diagnosis of Cauda equina syndrome is low. This means there should be a low threshold for performing an MRI spine in suspected cases.

MRI should be performed as soon as possible. In metastatic cord compression, MRI is recommended within 24 hours of presentation. CT of the spine is not recommended for the diagnosis but may be an alternative for patients who are unable to undergo MRI imaging.

Basic investigations should be requested looking for a possible underlying cause, any complications and in preparation for surgery (e.g. blood gas, basic blood tests, coagulation, group & save, ECG, bladder scan).

Question 22

Cauda equina syndrome is a …

Answer 22

Cauda equina syndrome is a neurosurgical emergency.

Question 23

Management of cauda equina

Answer 23

Cauda equina syndrome is considered a neurosurgical emergency, requiring operative management to prevent symptom progression and permanent paralysis.

Patients with Cauda equina syndrome should be discussed urgently with the most appropriate regional service (e.g. neurosurgeons, spinal orthopaedic team). The decision to proceed with emergency surgery depends on the acuity of the presentation and the extent of neurological dysfunction. The type of surgery depends on the aetiology with the overall goal to improve the space within the spinal canal and remove the agent leading to compression (i.e. decompressive surgery)

Patients with evidence of bladder dysfunction (e.g. urinary retention) generally need immediate surgery.

Question 24

Complications of cauda equina (long-term) - 5

Answer 24

Without intervention, cauda equina syndrome can lead to permanent paralysis.
There are many long-term complications associated with Cauda equina syndrome that include:

Bladder and bowel dysfunction
Sexual dysfunction
Chronic pain
Paralysis
Pressure ulcers

Question 25

The spinal cord ends at what anatomical level within the spinal canal?

Answer 25

The spinal cord originates at the base of the medulla oblongata, exiting the skull through the foramen magnum. It then extends through the spinal canal and ends at the level of the L1/L2 spinal vertebrae.