Thoracic Disc Disease

Epidemiology

 

0.05% incidence

- rare due to stabilising effect of rib cage

- even more rare to have symptoms

 

Reasoning

1.  Discs are narrower

2.  Foramina larger

3.  Thoracic spine

- facet joints orientated for rotation

- lumbar spine for flexion extension

- flexion is typically the motion which ruptures annulus

 

Anatomy

 

Increase in size from T1 to T12

- small pedicles

- long spinous processes

- relatively large intervertebral foramina

- facets nearly vertical

- TP come off the pedicle

- costal articulation TP and vertebral body

 

Thoracic Vertebrae

 

Clinical

 

Present with intercostal radiculopathy or myelopathy

 

Xray

 

Disc space narrowing / degenerative changes

 

> 50% thoracic discs associated with calcified disc material in canal

- probably indicates chronicity

 

Thoracic Disc Calcified CT 1Thoracic Disc Calcified CT 2

 

MRI 

 

Very sensitive 

- 40% incidence asymptomatic thoracic disc protrusion

 

Thoracic Herniate Disc SagittalThoracic Herniate Disc Axial

 

Thoracic Disc MRIThoracic Disc MRI Axial

 

Management

 

Non Operative

 

Indication

- single level disease

- no myelopathy

- operation rarely indicated

- usually settles with physiotherapy / analgesia

 

Operative

 

Indications

- myelopathy 

- unrelieved radiculopathy

 

Options

 

Posterior approach / discectomy via laminectomy

- contraindicated

- spinal cord does not tolerate retraction 

 

Anterior Approach

- costotransversectomy

- corpectomy (2 level disc)

 

A.  Thoracotomy and Costotransversectomy

 

Definition

- resection of rib + transverse process

 

Indication

- single level disc resection

- unilateral disc

 

Technique

- posterior approach

- remove of rib and transverse process

- ipsilateral pedicle removal

- removal disc protrusion

 

B.  Thoracotomy and Corpectomy

 

Indication

- 2 level disc protrusion

 

Thoracic disc 2 Level Precorpectomy

 

Technique

 

Thoractomy Approach

- loin incision

- removal of rib 2 levels above

- through bed of rib

- extrapleural approach

- from left to avoid IVC

 

Tie off segmental artery on one side

- disc convex, body concave

- allows access to disc protrusion

- discectomy + / - corpectomy as required for exposure / 2 level disc

- anterior +/- posterior stabilisation if corpectomy

- if simply remove disc may not need stabilisation especially in elderly

- will autofuse

 

Thoracic Corpectomy HNP

 

Complications

 

Cord injury

 

Cord infarct 

- ligation segmental artery

- exceedingly rare with unilateral approach

- much higher risk with bilateral approaches

- CTA to look for artery adamkiewicz

 

Intercostal neuritis 

- not uncommon

- treat with repeated intercostal nerve blocks

 

Bleeding

- usually from segmental artery

- patient presents difficulty breathing / hemothorax

- may have high output from drain

- > 200mls / hour clamp drain and urgent return to OT with vascular surgeon