Cauda Equina; Spinal Stenosis; Sarcoma

Question 1

Describe the anatomy of the cauda equina [1]

Answer 1

The cauda equina is a collection of nerve roots that travel through the spinal canal after the spinal cord terminates around L2/L3.

The spinal cord tapers down at the end in a section called the conus medullaris.

Question 2

Describe the innervation the nerve roots of the cauda equina supply [4]

Answer 2

• Sensory and motor innervation to the lower limbs
• Sensory innervation of the saddle area
• Motor innervation to the anal sphincters
• Parasympathetic innervation of the bladder

Question 3

In cauda equina syndrome, the nerves of the cauda equina are compressed. There are several possible causes of compression, including: [7]

Answer 3

• Herniated disc (the most common cause)
• Degenerative lumbar canal stenosis
• Tumours, particularly metastasis
• Spondylolisthesis (anterior displacement of a vertebra out of line with the one below)
• Abscess
• Trauma
• Infection (Potts; HSV; meningitis, or neurosyphilis)
• Late stage AS
• Spinal haemorrhage
• IVC thrombosis

Question 4

Describe why the nerve roots in the cauda equina are susceptible to damage [1]

Answer 4

They have a poorly developed epineurium surrounding their sheaths and do not have a segmental blood supply.

Question 5

What are the key red flad symptoms to look out for when investigating CES? [7]

Answer 5

• Saddle anaesthesia (loss of sensation in the perineum – around the genitals and anus)
• Loss of sensation in the bladder and rectum (not knowing when they are full)
• Urinary retention or incontinence
• Faecal incontinence
• Bilateral sciatica
• Bilateral or severe motor weakness in the legs
• Reduced anal tone on PR examination

Question 6

What are the key symptoms to ask about when investigating CES? [+]

Answer 6

Core diagnostic symptoms:
- Urinary dysfunction: difficulty starting or stopping stream; urinary retention; reduced bladder sensitivity; overflow incontinence
- Bowel dysfunction: constipation or faecal incontinence
- Sexual dysfunction
- Saddle anaesthesia

Accompanying symptoms: Symptoms may be unilateral or bilateral depending upon the aetiology
* Lower back pain with or without sciatica
* Lower limb sensory loss
* Lower limb lower motor neurone signs: most notably weakness, hypotonia and hyporeflexia

Question 7

CES can be classified into two groups based upon the clinical presentation. What are they? [2]

Answer 7

Cauda equina syndrome with retention (CESR): 50-60% of patients
* Presents with established urinary retention and/or overflow incontinence

Incomplete cauda equina syndrome (CESI): 40-50% of patients
* Presents without urinary retention or overflow incontinence. Patients may have reduced bladder sensation, loss of desire to void and/or poor urinary stream

Question 8

All patients with suspected CES require an urgent []

Answer 8

All patients with suspected CES require an urgent MRI scan to:
- Confirm or exclude a diagnosis of CES
If a diagnosis of CES is made, identify the level of compression and possible underlying cause

Question 9

Conus medullaris syndrome (CMS): The conus medullaris is the tapered end of the spinal cord which spans from T12-L2. Injuries to the lumbar vertebrae may result in compression of the conus medullaris, resulting in symptoms.

How would you differentiate this to CES? [2]

Answer 9

CMS differences: Sudden onset (typically after injury to the back); Patients have a mix of upper and lower motor neurone signs with hyperreflexia, weakness and fasciculations often being present.

Question 10

Which causes of CES require immediate surgical spinal decompression?

Answer 10

• After a lumbar disc herniation
• Spinal trauma and fractures
• Haematomas
• Space occupying lesions with radiological imaging indicating likely surgical removal
• Spinal stenosis

Question 11

Which patients with CES would not be suitable for sugery? [3] How would you treat them instead? [3]

Answer 11

Inflammatory disease such as late stage ankylosing spondylitis
* These patients may benefit from steroids

Infection
* These patients will be treated with antibiotics

Spinal neoplastic disease which is not suitable for surgical removal or where surgical removal was incomplete
* These patients should be given IV dexamethasone and be evaluated for chemo-radiotherapy

Question 12

Describe when dexamethasone treatment is used in CES [2]

Answer 12

If CES is caused by primary or metastatic malignancy, IV dexamethasone is recommended prior to surgical or other further intervention to try and reduce oedema which may be worsening compression of the cauda equina.

Question 13

Describe what is meant by (lumbar) spinal stenosis [1]

What are the primary [2] and secondary [4] causes?

Answer 13

Narrowing of the spinal canal in the lumbar region

Primary Causes
* Congenital Stenosis: This is an inherent condition where individuals are born with a narrow spinal canal. It is relatively rare but poses a significant risk for developing LSS.
* Achondroplasia: This genetic disorder impairs bone growth, leading to dwarfism. Individuals with achondroplasia often exhibit abnormal spine development, predisposing them to LSS.

Secondary causes
- Degenerative Changes: Age-related degenerative changes are the most common cause: OA; disc degeneration, and facet joint hypertrophy
- Spondylolisthesis: The forward displacement of one vertebra over another
- Trauma
- Tumours

Question 14

What are the three types of spinal stenosis [3]

Answer 14

Central stenosis – narrowing of the central spinal canal
Lateral stenosis – narrowing of the nerve root canals
Foramina stenosis – narrowing of the intervertebral foramina

Question 15

Describe the general presentation of LSS [5]

Answer 15

Neurogenic claudification
- bilateral, symmetrical buttock or lower extremity pain, numbness, and weakness that is exacerbated by lumbar extension

Radicular pain
- pain in dermatomal pattern
- accompanied by paraesthesia, numbness, or weakness

Back Pain:
- Often a combination of factors including degenerative disc disease, facet joint osteoarthritis, and ligamentum flavum hypertrophy.

Motor and sensory deficits:
- Specific to affected nerve root

Cauda Equina Syndrome

Question 16

How does central lumbar stenosis differ to lateral and foramina stenosis [1]

Answer 16

Lateral stenosis and foramina stenosis in the lumbar spine tends to cause symptoms of sciatica (unilateral pain from the buttock radiating down the back of the thigh to below the knee or feet.)

Intermittent neurogenic claudication is a key presenting feature of lumbar spinal stenosis with central stenosis. It is sometimes referred to as pseudoclaudication. Typical symptoms are:

Question 17

How do you differentiate CES and spinal stenosis? [1]

Answer 17

Symptoms of spinal stenosis tend to have a gradual onset, as opposed to cauda equina syndrome or sudden disc herniation with cord compression

Question 18

TOM TIP: The important thing for your exams is to spot the typical symptoms of intermittent neurogenic claudication. At first glance, they are similar to peripheral arterial disease.

How do you differentiate between them in an exam question?

Answer 18

The exam question might specify that the peripheral pulses or the ankle-brachial pressure index (ABPI) are normal, in which case the diagnosis is more likely to be spinal stenosis.

Additionally, patients with spinal stenosis are more likely to struggle with back pain, whereas back pain is not a feature of peripheral arterial disease.

Question 19

How do you investigate for spinal stenosis?

Answer 19

MRI scanning

Question 20

How do you differentiate between LSS and degenerative disc disease? [1]

Answer 20

DDD typically manifests as constant axial pain without a clear pattern of exacerbation or relief.

In contrast to lumbar spinal stenosis, DDD does not usually cause significant neurological deficits such as numbness or weakness in the legs.

NB: DDD is characterised by the breakdown of intervertebral discs leading to chronic low back pain.

Question 21

What is piriformis syndrome and how does it differentiate with LSSS? [1]

Answer 21

Piriformis Syndrome
- neuromuscular disorder occurs when the piriformis muscle compresses the sciatic nerve
- piriformis syndrome often presents unilaterally with symptoms exacerbated by sitting for prolonged periods, unlike lumbar spinal stenosis which typically causes bilateral symptoms exacerbated by standing or walking.

Question 22

Describe the management of LSS

Answer 22

Conservative management:
- NSAIDS; paracetamol; opoids
- Physio
- Epidural injections - temporary pain relief

Decompression surgery: removing bone or ligament tissue and relieving nerves
Spinal fusion: This procedure stabilises the spine by fusing two or more vertebrae together using grafts or hardware.

Question 23

Define sarcoma [1]

Answer 23

Sarcomas are cancers originating in the muscles, bones or other types of connective tissue.

Question 24

Describe three types of bone sarcoma [3]

Answer 24

Osteosarcoma – the most common form of bone cancer

Chondrosarcoma – cancer originating from the cartilage

Ewing sarcoma – a form of bone and soft tissue cancer most often affecting children and young adults

Question 25

State where each of the following sarcoma comes from:

Rhabdomyosarcoma
Leiomyosarcoma
Liposarcoma
Synovial sarcoma
Angiosarcoma
Kaposi’s sarcoma

Answer 25

Rhabdomyosarcoma – originating from skeletal muscle

Leiomyosarcoma – originating from smooth muscle cancer

Liposarcoma – originating from adipose (fat) tissue

Synovial sarcoma – originating from soft tissues around the joints

Angiosarcoma – originating from the blood and lymph vessels

Kaposi’s sarcoma – cancer caused by human herpesvirus 8, most often seen in patients with end-stage HIV, causing typical red/purple raised skin lesions but also affecting other parts of the body

Question 26

Describe the general presentation of sarcoma

Answer 26

Local symptoms:
- These are dependent on the site and size of the tumour. A palpable mass is the most common presenting feature.
- Pain may also be present, especially if there is nerve involvement or rapid tumour growth causing stretching of the surrounding tissues.

Systemic symptoms:
- These include fatigue, weight loss, and malaise. Although less common, these B symptoms suggest advanced disease or high-grade sarcomas.

Symptoms related to metastasis:
- Sarcomas most commonly metastasise to lungs leading to respiratory symptoms such as dyspnoea and chest pain.
- Other sites include bones (causing bone pain) and liver (leading to jaundice).

Question 27

Describe the specific presentations for Osteosarcoma; Ewing’s sarcoma; Leiomyosarcoma [3]

Answer 27

Osteosarcoma:
- Commonly presents with localised bone pain that worsens at night or with activity; occasionally accompanied by swelling around the affected area

Ewing’s sarcoma:
- Besides pain and swelling, systemic symptoms such as fever, malaise, and weight loss are often present due to the aggressive nature of this tumour

Leiomyosarcoma:
- Depending on its location, can cause a variety of symptoms. Uterine leiomyosarcoma may present with abnormal uterine bleeding while gastrointestinal leiomyosarcomas can cause abdominal pain or gastrointestinal bleeding.

Question 28

Describe the initial assessment used in diagnosis of a sarcoma [3]

Answer 28

MRI is the preferred modality due to its superior soft tissue contrast and multiplanar capability.

Employ PET-CT for systemic staging to detect metastasis.

Perform a biopsy, either core needle or incisional, for histopathological diagnosis. Avoid fine needle aspiration due to its limited diagnostic utility in sarcomas.

Question 29

The most common location for sarcoma to metastasise to is the [].

Answer 29

The most common location for sarcoma to metastasise to is the lungs.