Spinal Cord disease and Cauda Equina

Question 1

Where does the spinal cord extended from? Where do we take lumbar punctures from? What lies below?

Answer 1

1) SC extends from C1 (junction with medulla) to L1/L2 (conus medullaris).
2) Although cord ends at L1/L2 we take LP from L4 to be safe
3) Below L1 = lumbar and sacral roots that group together to form the caudate equine - final point of the cord.

Question 2

What is Paraplegia and Hemiplegia?

Answer 2

1) Paraplegia is the paralysis of BOTH LEGS always caused by a spinal cord lesion.
2) Hemiplegia is the paralysis of one side of the body caused by a lesion in the brain.

Question 3

What are the tracts of the cord?

Answer 3

1) Corticospinal - Motor, descending upper motor neurone, decussates at medulla
2) Dorsal column - ascending sensory tract (proprioception, vibration, fine touch, 2 point discrimination), decussates at medulla
3) Spinothalamic - ascending sensory tract (pain and temperature), decussated almost immediately in the spinal cord.

Question 4

Upper motor neurone signs:

Answer 4

1) Signs are contralateral to the lesion - indicating lesion is above the anterior horn cell i.e. in the spinal cord, brainstem, and motor cortex.
2) Increased muscle tone - spasticity: velocity dependent and non-uniform (faster you move the patients muscle the greater the resistance, until it finally gives way in a clasp-knife manner.
3) Weakness: Flexors tend to be weaker than extensors in legs and reverse in arms
4) Brisk reflexes - hyperreflexia

Question 5

Lower motor neurone signs:

Answer 5

1) Signs are ipsilateral to lesion - lesion is either in the anterior horn cell or distal to it i.e. in anterior horn cell, plexus, or peripheral nerve.
2) Decreased muscle tone
3) Wasting (atrophy) +/- fasciculations
4) Weakness that corresponds to these muscles supplied by the involved cord segment, nerve root, part of plexus or peripheral nerve.
5) Hyporeflexia (reduced or absent)

Question 6

How can level of problem be inferred?

Answer 6

1) Accompanying symptoms
2) Back pain and sciatica suggests root problem
3) Weakness of biceps with absence of bicep reflex, with UMN signs in the legs suggest cord disease e.g. disc prolapse at cg/c6 - LMN at that level and UMN below

Question 7

What is spondylolisthesis and spondylosis?

Answer 7

Spondylolisthesis - slippage of one vertebra over the one below. Nerve root comes out above the disc, therefore the root affected will be the one below the disc herniation e.g. L4/L5 herniation leads to an L5 nerve root compression.

Spondylosis - degenerative disc disease

Question 8

What is a myelopathy?

Answer 8

1) Caused by spinal cord compression - UMN lesion
2) UMN signs - spasticity, weakness, hyperreflexia
3) Spinal cord disease

Question 9

What is a radiculopathy?

Answer 9

1) Caused by spinal root compression - LMN signs
2) LMN signs - hypotonia, hyporeflexia, wasting, weakness and fasciculations
3) Pain down dermatome supplied by root
4) Weakness in myotome supplied by root
5) NO UMN SIGNS
6) Acute - NO LMN signs as fasciculations and wasting take time to develop

Question 10

Myotomes of C5, C6, C7, L3/4, L5, S1?

Answer 10

C5 - Shoulder abduction/biceps jerk
C6 - Elbow flexion/supinator jerk
C7 - Elbow extension/tricep jerk
L3/4 - Knee extension/knee jerk
L5 - Ankle dorsiflexion
S1 - Ankle plantar flexion/ankle jerk

Question 11

Dermatome landmarks?

Answer 11

C4 - Clavicle
C7 - Middle finder
T1 - Medial side of arm
T4 - nipple
T10 - Umbilicus

L2/3 - Anterior and inner leg
L4 - Knee
L5, S1-S2 - Posterior and outer leg
S4 - Perianal area

Question 12

Aetiology/RF of spinal cord compression (MYELOPATHY)?

Answer 12

• Compression of the spinal cord results in UMN signs and specific symptoms dependent on where the compression is.
• Vertebral body neoplasms (MOST COMMON CAUSE of acute compression - secondary malignancy commonly from lung, breast, prostate, myeloma, lymphoma.
• Spinal pathology:
  1) Disc herniation - When centre of disc (nucleus pulpous) has moved out through the annulus fibrosus (outer part), pressure on nerve root (and pain)
  2) Disc prolapse - When nucleus pulpous moved and presses against annulus but doesn’t escape outside. Can produce a bulge in disc, resulting in pressure on nerve root (and pain)
  3) Spinal stenosis - can occur in the central canal producing a myelopathy, or as the nerve roots exit the cord resulting in radiculopathy. Degenerative disease is the commonest.

Rarer causes: infection, haematoma, primary spinal cord tumour (glioma/neurofibroma).

Question 13

Clinical presentation of spinal cord compression?

Answer 13

1) Onset may be acute or chronic.
2) Spinal/root pain may precede leg weakness and sensory loss.
3) Progressive weakness of the legs with UMN signs (contralateral spasticity and hyperreflexia)
4) Arm weakness if often less severe (cervical cord lesion)
5) Bladder (and anal) sphincter involvement is late and manifests hesitancy, frequency, painless retention.
6) SENSORY LOSS BELOW LESION (sensory level) - abruptly dimities 1/2 segments below level of lesion.
7) Look for motor, reflex, sensory level (normal findings above level)
8) LMN signs at the level (especially in cervial cord compression) and UMN below the level - BUT tone and reflexes reduced initially in acute compression (takes time to develop)

Question 14

Presentation of L5/S1 lesion (SCIATICA)?

Answer 14

1) S1 nerve root compression - SCIATICA

2) Sensory loss/pain in back of thigh/leg/lateral aspect of little toe (in sciatic nerve distribution)

Question 15

Presentation of L4/L5 lesion?

Answer 15

1) L5 nerve root compression

2) Sensory loss/pain in lateral thigh/lateral leg and medial side of big toe

Question 16

Ddx of spinal cord compression?

Answer 16

1) Transverse myelitis
2) Multiple sclerosis
3) Trauma
4) Cord vasculitis
5) Dissecting aneurysm

Question 17

Diagnosis of spinal cord compression?

Answer 17

DO NOT DELAY IMAGING - irreversible paraplegia may follow if cord is not decompressed.

1) MRI GOLD STANDARD - cause and site
2) Biopsy/ surgical exploration required to identify nature of mass
3) Screening blood tests: FBC, ESR, B12, U&Es, syphillis serology, LFT, PSA
4) CXR - TB or malignancy e.g. primary lung malignancy

Question 18

Treatment of spinal cord compression?

Answer 18

1) If malignancy - IV DEXAMETHASONE (reduced oedema and inflammation around malignancy and improves outcome) and consider radio/chemo.
2) Epidural abscess must be surgically decompressed and antibiotics given
3) Refer to neurosurgeons -
1) Epidural steroid injection (effective for leg pain)
2) Surgical decompression:
- Laminectomy - removal of lamina/spongy tissue between discs to relieve pressure (common for spinal stenosis)
- Microdiscectomy - removal of herniated tissue from disc

Question 19

About Cauda Equina Syndrome:

Answer 19

• MEDICAL EMERGENCY
• Cauda Equina is formed by the nerve roots caudal (distal) to the level of the termination of the spinal cord at L1/L2.
• Spinal damage at or caudal to L1 - Cauda equina syndrome.
• Flaccid and areflexic weakness.
• Rare and occurs mainly in adults, and occurs in around 25 of herniated discs.
• Commonest cause is a lumbar disc herniation at L4/L5 or L5/S1.

Question 20

Aetiology of Cauda Equina syndrome?

Answer 20

• Usually large central disc herniations at L4/L5 or L5/S1
• Tumour/metastases
• Trauma
• Infections
• Spondylolisthesis
• Post-op haematoma

Question 21

Presentation of Cauda Equina syndrome?

Answer 21

• Major difference between Cauda Equina and lesions higher up in the cord is that leg weakness is flaccid and areflexic (LMN) and NOT spastic and hyperreflexic
• Sciatica is pain, numbness and tingling sensation that radiates from over back and travels down one of the legs to the foot and toes.

1) Bilateral sciatica
2) Saddle anaesthesia
3) Bowel/bladder dysfunction
4) Erectile dysfunction
5) Legs weakness - flaccid and areflexic

Question 22

Ddx of Cauda Equina:

Answer 22

1) Conus medullaris syndrome
2) Vertebral fracture
3) Peripheral neuropathy
4) Mechanical back pain

Question 23

Diagnosis of Cauda Equina?

Answer 23

1) MRI to localise lesion
2) Knee flexion - test L5-S1
3) Ankle plantar flexion (S1-S2)
4) Straight leg raising - L5, S1, root problem - people with acute disc can barely get leg off bed
5) Femoral stretch test - L4 root problem

Question 24

Treatment of Cauda Equina?

Answer 24

Refer to Neurosurgeon ASAP to relieve pressure - otherwise risk of permanent paralysis/sensory loss/incontinence.

1) Microdiscectomy - removal of part of the disc - may tear dura
2) Epidural steroid injection - effective for leg pain
3) Surgical spine fixation - if vertebra slipped
4) Spinal fusion - reduces pain from motion and nerve root inflammation