Spinal Cord Injury

Definition

 

Complete Lesion 

- bulbocavernosus reflex present 

- no cord function below lesion

- very poor prognosis for recovery

 

Incomplete Lesion

- bulbocavernosus reflex present

- some cord function below lesion

- good prognosis for recovery

 

Anatomy

 

Vertebral Canal narrowest at T8/9

- Also area of vascular watershed

 

Dorsal Columns 

- light touch, vibration & proprioception

- CTLS (cervical fibres central, sacral fibres lateral)

- decussate in medulla

- Cuneate Nucleus = Cervical & Thoracic

- Gracile Nucleus = Sacral & Lumbar

 

Lateral Corticospinal Tract

- motor tract

- CTLS (cervical central, sacral fibres peripheral)

- decussate in medulla

 

Anterolateral Spinothalamic Tract

- pain & temperature

- decussate immediately after cord entry

 

Incomplete Patterns

 

1.  Central Cord Syndrome

- most common

- hyperextension injury

- UL > LL due to arrangement of fibres in dorsal column and anterior corticospinal

- CTLS

- distal > proximal

- sacral sparing

 

2.  Anterior Cord Syndrome

- complete paralysis with dorsal column sparing

- anterior spinothalamic & lateral corticospinal tracts lost

- secondary to ischaemic event

- maintain BP and oxygenate patient

- very poor prognosis

 

3.  Brown Sequard

- cord hemisection

- usually secondary to laceration

- ipsilateral dorsal columns & motor

- contralateral loss pain & temperature

 

4.  Posterior Cord Syndrome

- rare

- dorsal column loss only

- due to tumour / iatrogenic (sublaminar wires etc)

 

5.  Cauda Equina Syndrome

- injury below L1

- only nerve roots at this level

- LMN injury to lumbar and sacral nerve roots

- large L5/S1 disc commonest cause in narrow canal < 100 mm2

- faecal incontinence + urinary incontinence

- nil anal tone or sensation

 

6.  Conus medullaris injury

- cord ends at L1

- injury at this level results in LMN LL weakness and UMN sacral lesions

- may have a spastic bladder which enables urination without catheterisation

- T12 / L1 burst fracture most common cause

 

Sacral Sparing

 

Triad of

- anal voluntary contraction

- perianal sensation

- FHL function

 

Indicates

- incomplete injury

- potential for recovery

- due to pial arteries on cord surface supplying small amount of tissue 

 

Blood Supply

 

Anterior Spinal Artery

- arises from vertebral arteries at foramen magnum

- supplies entire cord except for dorsal columns

- narrows and may become absent in thoracic region

 

Posterior Spinal Arteries

- paired

- smaller

 

Segmental Arteries

- average of 8 paired arteries

- may be single segmental supply between T4 and T8

- Artery of Adamkiewicz from left between T9-11 in 80% cases

 

Micturition control

 

Stretch receptors in bladder wall

 

As distension occurs

- afferent signal travels up pelvic splanchnic nerves (S2/3/4)

- sacral cell bodies send signal back via efferent in same nerves

- produce contraction of detrusor

 

Parasympathetic control

- this is a lower motor neuron reflex arc

- override by higher cortical centres with development

 

Cauda Equina

- LMN to S2-4

- flaccid bladder / overflow incontinence

 

Conus medullaris injury

- results in UNM changes at that level

- detrusor mm spastically contracts

- higher cortical control disrupted

- result is spastic bladder - incontinence

 

Surgical division sacral nerve roots 

- produces LMN effect

- if leave at least 1 S3 - 100% continent

- if leave at least 1 S2 - 50% continent

- if above S2 incontinent because pelvic splanchnics removed

 

Assessment

 

Spinal shock

 

Refers to flaccid paralysis due to physiologic disruption of all spinal cord function

- all motor, sensory and reflexes absent below level of injury

 

An accurate assessment can only be made when spinal shock has resolved

- 48 hrs in 99%

 

Absence of SS confirmed by the return of cord mediated reflexes below the anatomic level of the injury

- bulbocavernosus reflex is the lowest and thus the first to return

 

Frankel Grading

 

A Complete

- no motor or sensory function in the sacral region

 

B Incomplete

- sensory intact

- no motor function below the neurological level and includes sacral segments S4-S5

 

C Incomplete

- motor function is preserved below the neurological level 

- at least half the muscles have power < grade 3

 

D Incomplete

- motor function is preserved below the neurological level 

- at least half the muscles have power > grade 3

 

E Normal motor and sensory function

 

MRC Power Grading (Medical Research Council)

 

0 - no visible movement

1 - palpable or visible contraction

2 - active movement with gravity eliminated

3 - active movement against gravity

4 - active movement against some resistance

5 - active movement against full resistance

 

ASIA Dermatomes (American Spinal Injury Association)

 

C5 Elbow Flexor / Lateral Arm Sensation

C6 Wrist Extension / Dorsal thumb

C7 Elbow Extension / Dorsum MF

C8 Finger Flexion (MF DP) / Dorsum LF

T1 Interossei / Medial Arm sensation

T2 Armpit sensation

 

L1 Inguinal ligament sensation

L2 Hip Flexors / Middle Medial Thigh

L3 Knee extension / Knee sensation

L4 Ankle DF / Medial malleolus

L5 Long toe extension / First web space

S1 Ankle PF / Heel 

S2 Back of knee sensation

 

Each muscle rated 0 - 5 for power

- score out of 50 for R and L

- total score out of 100

 

Sensory Levels

 

T4 - nipple

T7 - xiphisternum

T10 - umbilicus

T12 - groin

 

Reflexes

 

Cremasteric Reflex T12-L1

- stroke thigh & scrotal contraction

 

Anal Wink S2-4

- stroke cleft for anal contract

 

Babinski

- upgoing = UMN

 

Oppenheimer

- stroke tibial crest & toes go up

 

Bulbocavernosus Reflex

 

Technique

- squeeze glans / clitoris or pull on catheter

- anal contracture

 

If present with complete cord lesion

- indicates S2-S4 region firing

- spinal shock resolved

- can prognosticate about level of neurological injury

 

Timing

- returns in 99% in 24 hours

- indicates end of spinal shock

 

TL fracture may permanently damage BCR

 

Medical Treatment

 

Steroids

 

Bracken N Engl J Med 1990

- randomised multi-centre trial

- methylprednisone v naloxone or placebo

- suggested benefits of corticosteroids within 8/24 but not after

- based on oedema reduction

- GIT haemorrhage may result or be exacerbated

 

Bracken Cochrance Database Syst Review 2012

- review of 8 randomised control trials

- shown that methylprednisolone, if given within 8 hours, improves motor recovery

 

Canadian Spine Society

- some of the efficacy seen in trials is only in post-hoc analysis

- evidence is actually very weak, level II and III

- side effects include sepsis, pneumonia and GI complications

- is not standard of care, but only a treatment option

 

Dosing

 

Methylpred

- 30 mg/kg bolus

- 5.4 mg/kg/hr for 23/24

 

Contra-indications

- > 8 hours after presentation

- penetrating spinal injury

- infection

- diabetes

- < 13 years old

- pregnancy

 

Surgical Decompression

 

Timing

 

Progressive neurology 

- urgent decompression

 

Non Progressive Neurology

- decompress as soon as stable

- timing uncertain

 

Results from decompression

 

Cervical

- improvement in both incomplete & complete cord injury

- 1 or 2 extra levels in cervical spine improves function significantly

 

Thoracolumbar

- improvement in incomplete cord injury

- no improvement with complete cord injury

- extra level in thoracic spine doesn't improve fuxnion

- prevents late degeneration / deformity / pain