Surgical discectomy via an approach tailored to herniation location · the spinal cord must NEVER be retracted · advanced
- The spinal cord MUST NEVER be retracted in thoracic discectomy — approach selection is dictated by herniation location so the disc can be worked AWAY from the cord under direct vision. Lateral/foraminal herniations are approached posterolaterally (transpedicular or costotransversectomy); central, broad-based and calcified herniations require an anterior or lateral extracavitary approach to avoid cord manipulation.
- Wrong-level surgery is the most common avoidable error in thoracic spine surgery — the thoracic level cannot be reliably counted from surface anatomy. Use intraoperative X-ray or CT localisation with a localising marker (needle, clamp) at the index level. A full-length AP and lateral radiograph from T1 to the lumbosacral junction is a prerequisite before positioning.
- The artery of Adamkiewicz (great anterior radicular artery, typically arising on the left between T9 and T11) supplies the anterior two-thirds of the lower thoracic spinal cord. Sacrifice of a segmental vessel near the herniation level, especially on the left, risks anterior spinal artery syndrome and paraplegia. Preoperative CT angiography or MR angiography to map the artery is strongly recommended before transthoracic or lateral extracavitary approaches.
- Calcified thoracic discs carry a significantly higher risk of dural adhesion and intradural extension — up to 30% of calcified discs have some degree of dural penetration at surgery (Stillerman). The surgeon must be prepared for an intentional durotomy with en-bloc resection of the disc and dura, followed by primary repair or patching to prevent CSF leak and postoperative pseudomeningocoele.
When & Why
Indications. The only absolute indication for urgent surgery is progressive myelopathy or acute paraplegia from cord compression — cord signal change, gait disturbance, lower-limb hyperreflexia, clonus, or bladder/bowel dysfunction constitutes a surgical urgency. Intractable radiculopathy (radicular pain or intercostal neuralgia) that has failed a 6-12 week trial of non-operative care is a relative indication. Significant cord compression with greater than 40% canal encroachment or cord deformation on MRI, even without dense myelopathy, warrants elective surgery because of the risk of progression. Contraindications. Absolute: an asymptomatic thoracic disc herniation found incidentally on MRI (the vast majority are asymptomatic and need no treatment), active systemic infection or uncontrolled coagulopathy, and comorbidities precluding the planned approach (poor pulmonary reserve for transthoracic; severe osteoporosis for instrumented reconstruction). Relative: multilevel disease where the symptomatic level cannot be confidently identified, previous ipsilateral thoracotomy or pleural adhesions making a transthoracic approach hazardous (consider contralateral or alternative approach), and morbid obesity (BMI greater than 40). Approach selection — the key preoperative decision. Every plan begins by classifying the herniation on axial MRI (and CT if calcified) in relation to the cord, then matching the approach to it: - Lateral/foraminal herniation (disc extends into the foramen lateral to the cord) → transpedicular or costotransversectomy (posterolateral).
- Central-lateral herniation (crosses the midline but reaches one side) → costotransversectomy or lateral extracavitary.
- Central/broad-based herniation (crosses the midline symmetrically) → transthoracic (anterior).
- Calcified central disc (hyperdense on CT) → transthoracic or lateral extracavitary — mandatory, not optional; a posterolateral approach is contraindicated.
- Upper thoracic (T1-T4) → posterolateral preferred (the sternum, great vessels and mediastinum limit anterior access).
- Thoracolumbar junction (T11-T12) → lateral extracavitary (avoids the diaphragm and pleural cavity), or transthoracic with diaphragmatic detachment. Preoperative imaging. MRI (sagittal and axial T1/T2) classifies the herniation and assesses cord compression and signal change. CT (sagittal and axial) is essential before every thoracic discectomy to assess calcification, osteophytes and possible intradural extension — a calcified disc changes the approach. CT or MR angiography is strongly recommended before an anterior or lateral approach at T5-L2 to map the artery of Adamkiewicz; if it arises at or immediately adjacent to the herniation level, the approach must be modified. Level localisation protocol. Obtain a full-length AP and lateral thoracic radiograph to count and mark levels, counting from T1 (which articulates with the first rib) on the sagittal MRI localiser and correlating with the radiograph. Intraoperatively, place a spinal needle, k-wire or haemostat in the spinous process of the level below the index disc (or mark the transverse process at the index level) and confirm with an intraoperative lateral radiograph or O-arm CT. It is safer to mark two adjacent levels and count to the disc space from the confirmed reference. The surgeon must personally confirm the level on imaging before incision. Consent specifically for spinal cord injury/paraplegia (1-5%), anterior spinal artery syndrome from Adamkiewicz injury, dural tear and CSF leak (5-15%, up to 30% with calcified discs), wrong-level surgery (1-5%), incomplete decompression, postoperative kyphosis, and — for the transthoracic approach — chest complications (pneumothorax, haemothorax, intercostal neuralgia, pneumonia; 10-20% overall). Setup. General anaesthesia with neuromuscular blockade (short-acting for MEP monitoring). MEP and SSEP are mandatory for all thoracic discectomies — obtain baselines after positioning but before incision; alert thresholds are an MEP or SSEP amplitude drop greater than 50%, or an SSEP latency increase greater than 10%. Maintain mean arterial pressure greater than 80 mmHg throughout the decompression phase. For the transthoracic approach use a double-lumen endotracheal tube for selective lung ventilation, an arterial line and consider a central line; a cell saver is reasonable when blood loss may exceed 500 mL.
The Operation
The goal is to remove the herniated disc and decompress the cord without ever retracting it — the entire strategy of approach selection exists so that instruments work away from the cord under direct vision. The exposure is laid out in full below: for central, broad-based and calcified discs the transthoracic (transpleural) approach is the gold standard because it lets the surgeon resect the disc from anterior to posterior, toward themselves, away from the cord; for lateral/foraminal discs the posterolateral family (transpedicular, costotransversectomy) reaches the disc lateral to the cord.
- Best for
- Lateral/foraminal disc
- Position
- Prone
- Working corridor & cord safety
- Through the pedicle, lateral to the cord; instruments tangential to the cord, cannot cross the midline
- Key at-risk structures
- Pedicle, lateral thecal sac, exiting nerve root
- Best for
- Central-lateral disc
- Position
- Prone
- Working corridor & cord safety
- Through the costotransverse defect, a more lateral angle than transpedicular; cannot safely reach the midline
- Key at-risk structures
- Intercostal neurovascular bundle, pleura
- Best for
- Central/calcified/revision; thoracolumbar junction
- Position
- Prone or three-quarter prone
- Working corridor & cord safety
- Retropleural channel anterior to the cord without entering the pleural cavity
- Key at-risk structures
- Segmental vessels (Adamkiewicz), intercostal nerve, pleura
- Best for
- Central/broad-based/calcified disc
- Position
- Lateral decubitus
- Working corridor & cord safety
- Anterior to the cord with direct ventral visualisation; disc resected toward the surgeon, away from the cord
- Key at-risk structures
- Intercostal bundle, segmental vessels, azygos/thoracic duct, lung, diaphragm
Operative sequence — transthoracic (transpleural) approach
- Lateral decubitus, side of approach determined by herniation location (usually the right side for central discs to avoid the heart, aorta and thoracic duct; left if the herniation is asymmetrically left-sided, but only after CTA to map Adamkiewicz).
- Axillary roll under the dependent axilla, flex the table to open the intercostal spaces, arm in an overhead armrest or on a Mayo stand (avoid brachial plexus stretch).
- Confirm double-lumen tube position and ipsilateral lung deflation with bronchoscopy before draping.
- For T4-T10, a posterolateral thoracotomy through the intercostal space at the level of the disc or one level above (the rib crosses at the pedicle level — entering one level above gives access to the disc). T4-T5 is usually right-sided; T11-T12 may need a thoracoabdominal incision with diaphragmatic detachment.
- Divide latissimus dorsi, serratus anterior and intercostal muscles in the line of the incision and enter the pleural space.
- Resect the rib at the level of the incision (usually the rib above the disc space) — removing 4-6 cm of rib posterior to the costochondral junction provides the exposure.
- Resect the rib subperiosteally to protect the intercostal neurovascular bundle and pleura (dissect on the superior surface of the rib — the neurovascular bundle runs in the subcostal groove on the inferior surface).
- Place a rib spreader (Finochietto or Tuffier) and open gradually to avoid rib fracture.
- Retract the deflated lung anteriorly (covered with a moist lap sponge).
- Identify the segmental vessels overlying the lateral vertebral body — the intercostal artery and vein run transversely across the mid-vertebral body. The aorta lies on the left, the azygos/hemiazygos vein on the right — palpate and protect them.
- Confirm the level by intraoperative radiography or navigation (a spinal needle placed into the disc is the most reliable method).
- Ligate the segmental vessels at the level of the disc and one level above and below, dividing 5-10 mm away from the aorta (left) or azygos (right) using clips or silk ties.
- Critical: if preoperative CTA/MRA has shown the artery of Adamkiewicz arising at or adjacent to the herniation level, do NOT ligate that segmental vessel — consider a temporary occlusion trial with neuromonitoring or a different approach.
- Mark the disc space and adjacent vertebral body margins and verify with a spinal needle and X-ray.
- With a high-speed burr (4-5 mm cutting, then diamond at the posterior cortex), create a trough in the vertebral body about 15-18 mm wide, extending from the endplate above the disc to the endplate below.
- Resect the posterior portion of the vertebral bodies above and below the disc to create the working window through which the disc and posterior longitudinal ligament (PLL) are approached.
- Depth control: preserve a thin shell of posterior vertebral cortex until the final step — feather it down to a paper-thin layer with the diamond burr before removal.
- The critical manoeuvre: the disc is now approached from ANTERIOR to the cord. The herniated material is resected TOWARD the surgeon, AWAY from the cord.
- Remove disc material with micro-curettes, pituitary rongeurs and angled dissectors, working anterior to posterior.
- Remove the PLL with a micro-hook or Kerrison rongeur to expose the ventral dura.
- Verify complete decompression — the ventral dura should be visible and pulsatile across the full width of the canal to the opposite pedicle.
- For a calcified disc adherent to the dura, use a diamond burr to thin the calcified mass from the vertebral body side until only a thin eggshell layer remains against the dura, then dissect it off gently with a micro-dissector.
- If the disc has penetrated the dura, do NOT peel it free — plan an intentional durotomy: open the dura 2-3 mm around the adherent disc and resect the disc and involved dura en bloc (pulling a densely adherent calcified fragment away tears the dura uncontrollably and enlarges the defect).
- Repair primarily with 6-0 Prolene or Gore-Tex (interrupted figure-of-eight sutures). If the defect is larger than 5 mm or the dura is friable, patch with autologous fascia lata, bovine pericardium or a dural substitute, sutured water-tight, then apply fibrin glue.
- Achieve meticulous haemostasis — bone wax for vertebral cancellous bone, bipolar and haemostatic matrix for epidural vessels.
- The corpectomy defect does not routinely need reconstruction after a single-level discectomy with intact endplates (controversial — some place a structural graft to prevent kyphosis); if reconstructed, use iliac crest/rib autograft or a titanium cage under compression.
- Close the pleura over the spine with a running absorbable suture to make it water-tight (a pleural or pericardial fat flap is a fallback).
- Place a 24-28 Fr chest tube through a separate stab incision, positioned to drain the posterior pleural space, on underwater seal at -20 cm H2O suction (use gravity/water seal only if a dural repair has been performed — suction can siphon CSF through the repair).
- Re-inflate the lung under direct vision and confirm full expansion; intercostal nerve block (bupivacaine 0.25-0.5%, 2-3 mL per space, two levels above and below) for analgesia; layered closure approximating the ribs with heavy absorbable suture.
Operative sequence — posterolateral approaches (transpedicular / costotransversectomy)
- Prone on a standard frame (Jackson, Wilson or four-poster) with chest and iliac crest supports and the abdomen free to reduce epidural venous pressure; arms above the head (ski-jump) to allow lateral fluoroscopy; slight reverse Trendelenburg.
- Maintain the thoracic kyphosis — do not flatten it (this narrows the canal and increases cord tension).
- Midline incision (transpedicular) or paramedian incision 2-3 cm lateral to the midline on the side of the herniation (costotransversectomy), centred over the index level.
- Subperiosteal dissection of the paraspinal muscles to expose the spinous processes, laminae and transverse processes (and the medial 5-6 cm of rib for costotransversectomy) of the target and adjacent levels.
- Confirm the level with intraoperative radiography or navigation, placing a marker on the transverse process or lamina and cross-referencing the preoperative count.
- Transpedicular: with a high-speed burr resect the inferior facet above and the superior facet below (partial facetectomy), identify the pedicle at the junction of the transverse process and lateral lamina, and drill an 8-10 mm window through its cancellous bone into the posterolateral disc space. The medial pedicle wall is the canal boundary — thin it with a diamond burr and remove the remaining cortex with a Kerrison to expose the lateral canal.
- Costotransversectomy: resect the transverse process with a rongeur, then resect the medial 3-4 cm of rib (including the rib head) subperiosteally (dissect on the superior surface of the rib to protect the intercostal neurovascular bundle in the subcostal groove). Remove the rib head and costotransverse ligament to expose the lateral vertebral body and pedicle, then resect the pedicle of the level above the disc to create a 10-12 mm window.
- Pleura: lies immediately anterior and inferior to the rib bed — if violated, repair primarily with 4-0 absorbable suture or a sealant.
- With the window open, identify the lateral border of the cord/thecal sac; the disc space lies just anterior to the plane of the pedicle — a blunt nerve hook or dental probe palpates it.
- The herniated material is seen as soft or calcified tissue protruding into the lateral recess.
- With a nerve hook or micro-dissector, gently mobilise the herniated material BACK toward the surgeon (away from the cord) — the instrument tip must never push material toward the cord.
- Resect the fragment and adjacent disc with small pituitary rongeurs and micro-curettes; a 45-degree or 90-degree angled curette helps reach across the midline in costotransversectomy.
- The cardinal rule: if any instrument or retractor must contact the cord to visualise or resect the herniation, the approach is wrong — convert to a more extensile (costotransversectomy or transthoracic) approach.
- Limit annular resection to the herniated quadrant — the annulus preserves anterior stability.
- Inspect the lateral cord and nerve root — they should be free and pulsatile; confirm the disc space is decompressed with a blunt nerve hook.
- Confirm MEP and SSEP remain stable or improved from baseline. If a central herniation cannot be fully resected through this window, convert to a transthoracic approach.
- Check for pleural violation — if present, repair and place a small chest tube (20-24 Fr) on underwater seal.
- If the pleura is intact, layered closure over a suction drain (15 Fr, deep to muscle, exiting laterally through a separate stab).
- Intercostal nerve block at the level of resection for postoperative analgesia.
- A unilateral single-level facetectomy does not routinely need instrumented fusion; bilateral facetectomy or multilevel resection does.
Lateral extracavitary approach (summary). A posterolateral exposure that combines features of costotransversectomy and a lateral retropleural approach for central, calcified or revision discs where ventral access is needed but transthoracic entry is undesirable (pleural adhesions, thoracolumbar junction, wish to avoid lung deflation). Prone or three-quarter prone with the herniation side elevated, a curved paramedian incision (5-6 cm lateral to midline) or a large midline flap mobilises the paraspinal muscles over 2-3 levels; the transverse process and 5-6 cm of medial rib are resected and the pleura is swept anteriorly off the vertebral body with blunt/Kittner dissection to create a working channel anterior to the cord without entering the pleural cavity. Segmental vessels are ligated (with the same Adamkiewicz precautions) and the disc is resected through a lateral vertebrectomy window, identical in principle to the transthoracic approach. If the pleura stays intact no chest tube is needed; if violated, repair and place a chest tube, with a deep suction drain in the retropleural cavity.
The thoracic cord occupies 40-50% of the canal (against under 25% in the lumbar spine) and the mid-thoracic region (T4-T9) is its vascular watershed, where the anterior spinal artery is narrowest and receives the fewest radicular feeders. Even gentle retraction can cause irreversible cord ischaemia and permanent motor loss. The entire strategy of approach selection exists to avoid needing to retract the cord — choose the approach that lets the herniation be resected without any cord contact, maintain MAP greater than 80 mmHg throughout decompression, and use MEP/SSEP monitoring throughout.
Central disc calcification on CT signals dense dural adhesion and possible intradural extension (up to 30% of calcified discs show dural penetration at surgery). An anterior approach (transthoracic or lateral extracavitary) is mandatory for these discs — it allows the disc-dura interface to be dissected under direct vision and, if needed, an intentional durotomy with en-bloc disc-and-dura resection and primary repair. A posterolateral approach through a narrow corridor is contraindicated: it cannot safely separate an adherent calcified fragment and risks uncontrolled dural tearing.
Aftercare & Complications
Rehabilitation | Phase | Timing | Key management | |-------|--------|----------------| | Immediate (Day 0-1) | 0-24 h | Hourly neurovascular observations; MAP greater than 80 mmHg for 24 h; multimodal analgesia; transthoracic — chest tube on underwater seal, immediate CXR, incentive spirometry 10 breaths/hour, nil by mouth until bowel sounds return | | Early (Day 1-3) | 1-3 days | Mobilise with physiotherapy from day 1 if neurologically stable; DVT prophylaxis (mechanical from day 0, chemical from day 1 if no dural tear); chest tube removed when output less than 100-150 mL/24 h, no air leak, full lung expansion on CXR | | Intermediate (Day 4-14) | 4-14 days | Sutures/staples out at 10-14 days (posterior) or 14 days (transthoracic); no lifting greater than 5 kg, no bending or twisting for 6 weeks; driving deferred 4-6 weeks | | Long-term | 6 weeks to 12 months | Core and postural physiotherapy; low-impact sport at 3 months, contact sport at 6-12 months; standing AP/lateral at 6 weeks, 3 and 12 months; MRI only for new symptoms | Return to work is roughly 4-6 weeks for sedentary/desk roles and 12-16 weeks for manual work. If a dural repair has been performed, nurse flat for 48 hours and run a lumbar drain at 10-15 mL/hour for 3-5 days, weaning by a 24-hour clamp trial before removal. Complications
- Incidence
- 1-5% depending on series and approach
- Recognition
- Immediate loss of MEP/SSEP during or after decompression; postoperative paraplegia or profound motor weakness, with or without sensory loss; anterior cord pattern if vascular (preserved posterior columns)
- Prevention and management
- Prevention: never retract the cord; select an approach that works away from the cord; maintain MAP greater than 80 mmHg; MEP/SSEP throughout. Management: for acute intraoperative MEP loss — stop, warm to normothermia, raise MAP above 85 mmHg, check haemoglobin (transfuse if below 8 g/dL), consider methylprednisolone per NASCIS (controversial, individualise); postoperative — urgent MRI, and return to theatre for evacuation of haematoma or residual compression
- Incidence
- 0.5-3% (approach-dependent)
- Recognition
- Immediate or delayed flaccid paraplegia with preserved posterior column function (vibration, proprioception, light touch); MEP loss with preserved SSEP
- Prevention and management
- Prevention: preoperative CTA/MRA to map Adamkiewicz; do not ligate the segmental vessel at the level of the artery; consider temporary occlusion with MEP monitoring before permanent ligation; avoid left-sided approaches at T9-T11 without imaging. Management: MAP augmentation; transfer to a spinal cord injury unit. Prognosis for motor recovery is poor once infarction has occurred
- Incidence
- 5-15% (up to 30% with calcified discs)
- Recognition
- Intraoperative visible CSF egress; postoperative positional headache (worse upright, better supine), CSF from the wound, pseudomeningocoele on MRI/CT
- Prevention and management
- Prevention: preoperative CT for calcification; plan for intentional durotomy in adherent calcified discs; thin calcified fragments with a diamond burr before dissection. Management: primary repair with 6-0 Prolene/Gore-Tex; patch (autologous fascia, bovine pericardium, dural substitute) if large or friable; fibrin glue; lumbar drain 3-5 days if tenuous; water-tight pleural closure in the transthoracic approach
- Incidence
- 1-5% (higher than cervical or lumbar)
- Recognition
- Discectomy at the incorrect level — recognised intraoperatively (if localisation confirms it) or postoperatively (persistent symptoms with wrong level on imaging)
- Prevention and management
- Prevention: preoperative full-length localiser radiograph; intraoperative confirmation with a marker at the index level; count from T1 (first rib) on MRI and radiograph; confirm two adjacent levels on intraoperative X-ray; use navigation/O-arm. Management: if recognised intraoperatively, confirm and proceed at the correct level; if postoperative, return to theatre, disclose and document, and institute a wrong-level prevention protocol
- Incidence
- 10-20% overall
- Recognition
- Pneumothorax (air leak or persistent on CXR); haemothorax (output greater than 200 mL/hour or falling haemoglobin); pleural effusion; intercostal neuralgia; pneumonia (fever, productive cough, infiltrate)
- Prevention and management
- Prevention: meticulous pleural closure; intercostal nerve block at closure; early mobilisation and incentive spirometry. Management: pneumothorax — water seal trial, then chemical pleurodesis or re-operation if the leak persists beyond 5-7 days; haemothorax — return to theatre if output greater than 200 mL/hour for more than 3 hours; effusion — diurese, thoracentesis; neuralgia — gabapentinoids and intercostal block; pneumonia — culture, antibiotics, respiratory therapy
- Incidence
- 5-10% (higher with posterolateral approaches for central discs)
- Recognition
- Persistent or recurrent symptoms; residual fragment on postoperative MRI; failure of MEP/SSEP to improve or worsening
- Prevention and management
- Prevention: appropriate approach selection; verify decompression intraoperatively — inspect the ventral dura across the midline to the opposite pedicle; use intraoperative ultrasound/navigation if in doubt. Management: revision via a more extensile approach if symptomatic with persistent cord compression; observe if asymptomatic without cord compromise
- Incidence
- Less than 5% after single-level discectomy; higher after multilevel or bilateral facetectomy
- Recognition
- Progressive kyphotic deformity on standing films (Cobb progression greater than 10 degrees); axial back pain; neurological deterioration if it progresses
- Prevention and management
- Prevention: limit facet resection to one side; consider instrumented fusion after bilateral facetectomy, corpectomy or multilevel discectomy; preserve the posterior tension band. Management: observe if asymptomatic and under 20 degrees; posterior instrumented fusion (2 levels above and below) if symptomatic or progressive
Viva & Exam Focus
THORACICTHORACIC — key principles of thoracic discectomy
DISC HERNIADISC HERNIA — approach selection
Critical danger structures and exam traps
The trap: counting ribs or vertebral bodies from surface anatomy (C7 prominence, T12 rib) is unreliable — up to 15% of thoracic procedures have incorrect level localisation in some series, and T2 is hard to identify on an intraoperative lateral because the shoulders overlap. The fix: use a preoperative full-length localiser radiograph; place a localising needle, k-wire or towel clip in a spinous process at the intended level and confirm with AP and lateral X-ray or CT before incision; cross-reference with MRI by counting from T1 (first rib); never rely on a single view.
Mechanism: the thoracic cord has a watershed blood supply in the mid-thoracic region (T4-T9), where the anterior spinal artery is narrowest and receives the fewest radicular feeders — even gentle retraction can cause cord ischaemia and permanent motor loss. Prevention: choose an approach that allows the herniation to be resected without any cord contact. Lateral discs: transpedicular or costotransversectomy reaches the disc lateral to the cord. Central/broad-based discs: transthoracic or lateral extracavitary gives direct visualisation without retraction.
Location: most commonly arises from a left posterior intercostal artery between T9 and T11 (75% of individuals), but can arise from T5-L4 and from the right in up to 25%. It joins the anterior spinal artery and supplies the anterior two-thirds of the lower thoracic and upper lumbar cord. Risk and prevention: sacrifice of its feeding segmental vessel risks anterior spinal artery syndrome — flaccid paraplegia with preserved posterior columns. Preoperative CTA or MRA in all patients having an anterior or lateral approach to the lower thoracic spine; if it arises at or adjacent to the herniation level, choose a different approach or temporary clamping with neuromonitoring.
Risk: calcified thoracic discs adhere to the ventral dura in a significant proportion; in Stillerman's series up to 30% showed some dural penetration at surgery, and the disc and dura may be inseparable. Management: plan for an intentional durotomy with en-bloc resection of the disc and adherent dura, then primary repair (6-0 Prolene or Gore-Tex) or patching with autologous fascia, bovine pericardium or a dural substitute; apply sealant and manage the drain. A more extensile approach (lateral extracavitary or transthoracic) gives better access for repair than a narrow posterolateral corridor.
The error: attempting a posterolateral (transpedicular/costotransversectomy) approach for a central, broad-based or calcified disc that cannot be safely resected without cord manipulation — the narrow working angle through the pedicle and facet pushes instruments toward the cord. The fix: classify the herniation on axial MRI (and CT if calcified). Lateral/foraminal = posterolateral. Central, broad-based or calcified = anterior (transthoracic, thoracoscopic) or lateral extracavitary. A midline central disc cannot be safely resected from a unilateral posterolateral window.
Risk: the transpleural approach needs lung deflation, rib resection/spreading and pleural entry — persistent air leak (5-10%), haemothorax, intercostal neuralgia, pleural effusion, pneumonia and chest-tube-related complications. Mitigation: meticulous water-tight pleural closure; chest tube (24-28 Fr) on underwater seal at -20 cm H2O suction; remove when output is less than 100-150 mL/24 h and no air leak; intercostal nerve block at closure to reduce pain and splinting.
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 52-year-old woman has a 3-month history of bilateral lower-limb weakness, gait unsteadiness and urinary urgency. MRI shows a large central, broad-based T8-T9 disc herniation with cord compression and cord signal change; CT shows the disc is heavily calcified. She is otherwise fit. How do you manage her surgically?”
“A 38-year-old man has a 6-month history of right-sided intercostal neuralgia at T6-T7. MRI shows a right-sided lateral T6-T7 disc herniation with foraminal extension; there is no myelopathy and no cord compression, and CT shows no calcification. He has failed 8 weeks of conservative treatment. How do you manage him surgically?”
“During a transthoracic discectomy for a calcified T10-T11 disc, the calcified fragment is adherent to the ventral dura. As you dissect it off, a 4 mm dural defect occurs with visible CSF egress, and the fragment is still partly attached to the dura. How do you manage this intraoperatively?”
Surgical indications
- Progressive myelopathy or acute paraplegia from cord compression — absolute surgical urgency
- Intractable radiculopathy after 6-12 weeks of failed conservative care — relative indication
- Cord compression with greater than 40% canal compromise on MRI — elective surgical consideration
- Asymptomatic thoracic disc herniations are incidental findings — do NOT operate
Approach selection (the key decision)
- Lateral/foraminal herniation → posterolateral approach (transpedicular or costotransversectomy)
- Central/broad-based herniation → anterior approach (transthoracic transpleural)
- Calcified disc (hyperdense on CT) → ANTERIOR approach — mandatory; posterolateral is contraindicated
- Upper thoracic (T1-T4) → posterolateral preferred; sternum and great vessels limit anterior access
- Thoracolumbar junction (T11-T12) → lateral extracavitary (avoids diaphragm and pleural cavity)
Operating principles
- NEVER retract the thoracic spinal cord — the watershed blood supply (T4-T9) is vulnerable to ischaemia
- Work AWAY from the cord, not toward it — the disc is resected back toward the surgeon
- MEP and SSEP monitoring is mandatory; MAP greater than 80 mmHg throughout decompression
- Preoperative CT angiography or MRA to map the artery of Adamkiewicz before anterior/lateral approaches
- Artery of Adamkiewicz arises on the left at T9-T11 in 75% of patients — protect it
Operative steps — transthoracic approach
- Double-lumen tube, lateral decubitus, right-sided approach at T4-T10 (avoids heart, aorta, thoracic duct)
- Posterolateral thoracotomy at the intercostal space above the disc; resect 4-6 cm of rib
- Deflate the ipsilateral lung, retract anteriorly, identify segmental vessels at the disc level
- Ligate segmental vessels away from the aorta; do NOT ligate the Adamkiewicz feeder
- Create a 15-18 mm corpectomy trough in the bodies above and below the disc (burr to eggshell then remove)
- Resect disc anterior to posterior — micro-curettes and rongeurs toward the surgeon, away from the cord
- Remove the PLL — verify the ventral dura is decompressed to the contralateral pedicle
- For calcified adherent discs: intentional durotomy, en-bloc disc-dura resection, primary repair with 6-0 Prolene
- Water-tight pleural closure, 24-28 Fr chest tube, re-inflate the lung under direct vision
- Corpectomy defect: graft or cage reconstruction only if substantial bone resection (controversial for simple discectomy)
Danger zones
- Wrong-level surgery: intraoperative radiographic confirmation with a marker at the index level — never rely on surface anatomy or a single view
- Spinal cord ischaemia: no retraction, MAP greater than 80 mmHg, MEP/SSEP monitoring, segmental vessel protection
- Artery of Adamkiewicz: left T9-T11 in 75%; CTA/MRA before any anterior approach at T5-L2
- Calcified disc-dura adhesion: 15-30% dural tear rate; prepare for intentional durotomy and repair
- Chest tube to gravity (not suction) if a dural repair is performed, to avoid a siphon effect on CSF
Major complications
- Spinal cord injury/paraplegia: 1-5% — from ischaemia, retraction, haematoma or residual compression
- Anterior spinal artery syndrome: loss of Adamkiewicz — flaccid paraplegia with preserved posterior columns
- Dural tear/CSF leak: 5-15% overall, up to 30% with calcified discs — primary repair, lumbar drain, flat bed rest
- Wrong-level surgery: 1-5% — always confirm the level intraoperatively
- Chest complications: pneumothorax, haemothorax, pleural effusion, intercostal neuralgia, pneumonia — 10-20%
Post-op management
- MAP greater than 80 mmHg for 24 hours — spinal cord perfusion is critical
- Mobilise with physiotherapy from day 1 if neurologically stable
- Remove the chest tube when output is less than 100-150 mL/24 h, no air leak, full lung expansion on CXR
- Lumbar drain for 3-5 days if a dural repair is performed — drain at 10-15 mL/hour, nurse flat
- Return to work: desk 4-6 weeks, manual 12-16 weeks; no heavy lifting or twisting for 6 weeks
Special cases
- Calcified disc: mandatory anterior approach; 15-30% dural tear rate; plan an intentional durotomy
- Intradural disc herniation: rare (less than 5%); anterior approach mandatory; en-bloc disc-dura resection
- Upper thoracic (T1-T4): posterolateral approach preferred; trans-sternal reserved for central calcified discs
- Thoracolumbar junction (T11-T12): lateral extracavitary approach avoids the diaphragm and pleural entry
Background & Evidence
Epidemiology. Thoracic disc herniation accounts for only 0.25% to 0.75% of all disc herniations, and most are incidental imaging findings; surgery is appropriate only for symptomatic herniations that correspond precisely to the clinical level and imaging abnormality. Peak presentation is in the fourth to sixth decades and the lower thoracic spine (T8-T12) is most commonly involved. Natural history and non-operative care. The natural history of asymptomatic thoracic disc herniations is generally benign — most do not progress or become symptomatic (Wood, 1997), which is why incidental findings should not be operated. For radiculopathy alone, a 6-12 week trial of observation, simple analgesics (paracetamol, NSAIDs), activity modification and physiotherapy is reasonable; neuropathic agents (gabapentinoids, amitriptyline) may help radicular pain but have no effect on cord compression and must not delay surgical referral if myelopathy develops. Image-guided intercostal nerve blocks can give temporary relief and help confirm the symptomatic level; transforminal epidural steroid injections carry a higher risk of cord injury than in the lumbar spine and are not routinely recommended; chemonucleolysis has no role. Classification. Thoracic disc herniations are classified by location on the axial image, which directly dictates the corridor: lateral (within or lateral to the foramen — posterolateral approach), centrolateral (crossing toward the midline — costotransversectomy or lateral extracavitary), and central/broad-based (symmetric across the midline — transthoracic). Calcification on CT is a modifier that independently mandates an anterior approach. Thoracic spinal anatomy relevant to the operation. The thoracic vertebral body is heart-shaped on axial view with costal facets for the rib head; pedicles are short, stout and narrow (mean 4.5-5.5 mm), making pedicle screw placement demanding. Laminae are broad and shingled in the upper/mid-thoracic spine (limiting interlaminar access), and spinous processes are long and steeply angled. Each rib articulates at the costovertebral joint (rib head with body and disc) and the costotransverse joint (rib tubercle with transverse process); the rib head covers the posterolateral disc corner, so about 3-4 cm of rib is resected in a costotransversectomy. Spinal cord and vascular anatomy. The thoracic cord occupies about 40-50% of the canal (against under 25% lumbar) — less reserve — and tapers to the conus at about L1. The mid-thoracic region (T4-T9) is the vascular watershed: the anterior spinal artery is narrowest here and fed by the fewest radicular arteries, making it most vulnerable to ischaemia from hypotension, retraction or segmental vessel sacrifice. The anterior spinal artery supplies the anterior two-thirds of the cord (corticospinal and spinothalamic tracts); its injury produces anterior cord syndrome (bilateral motor loss and loss of pain/temperature with preserved posterior-column function). Paired posterior spinal arteries supply the posterior third (dorsal columns) and are better collateralised.
- Details
- A single dominant anterior radicular artery in about 80% of individuals
- Details
- Typically a left posterior intercostal artery (75% on the left)
- Details
- T9-T11 in 65-75%; can arise anywhere from T5 to L4
- Details
- Runs with the nerve root through the foramen, then joins the anterior spinal artery
- Details
- Supplies the lower thoracic and upper lumbar anterior cord (T8 to conus)
- Details
- Visible on CT angiography and MR angiography in more than 90% of cases with modern protocols
- Details
- Sacrifice at the level of the herniation risks anterior spinal artery syndrome
Outcomes by approach. Stillerman (1998) reported good/excellent outcomes in 82% of 82 patients having anterior decompression, with the best recovery in patients with myelopathy or radiculopathy and a preoperative deficit of less than 6 months. Borm (2004) reported satisfactory outcomes in about 80% after transpedicular discectomy, with lower morbidity than transthoracic approaches but applicability limited to lateral/foraminal herniations. The lateral extracavitary approach gives ventral access without entering the pleural cavity — useful at the thoracolumbar junction and for revision. Anand and Regan (2002) established video-assisted thoracoscopic surgery (VATS) as a viable minimally invasive alternative for carefully selected lateral and centrolateral herniations. Prognosis is best when preoperative myelopathy has been present for less than 6 months and in younger patients (less than 50 years), though decompression is effective across all age groups.
References
Experience in the surgical management of 82 symptomatic herniated thoracic discs and review of the literature
- 82 patients with symptomatic thoracic disc herniations treated surgically — the largest single-centre series at publication
- Good/excellent outcome in 82% of patients; best neurological recovery in patients with a preoperative deficit of less than 6 months
- Disc calcification associated with dural adhesion in approximately 30% of cases — recommend an anterior or lateral approach for calcified discs
- Revision rate of 7%, predominantly for incomplete resection via a posterolateral approach
Thoracic disc herniation: operative approaches and results
- Landmark early series of 12 patients undergoing transthoracic discectomy for central and calcified thoracic disc herniations
- Demonstrated that central thoracic discs can be safely resected via an anterior transthoracic approach without spinal cord retraction
- Reported no cases of neurological deterioration and good functional recovery in all patients
Video-assisted thoracoscopic surgery for thoracic disc disease: classification and outcome study of 100 consecutive cases with a 2-year minimum follow-up
- Largest single-centre series (100 consecutive cases) of video-assisted thoracoscopic surgery (VATS) for thoracic disc disease with a minimum 2-year follow-up
- Introduced a classification of thoracic disc herniations by location (central, centrolateral, lateral) that guides the surgical corridor
- Demonstrated that VATS is a viable minimally invasive alternative to open transthoracic discectomy for carefully selected lateral and centrolateral herniations, with reduced access-related morbidity
The natural history of asymptomatic thoracic disc herniations
- Serial MRI study of patients with asymptomatic thoracic disc herniations identified incidentally on imaging
- The vast majority of asymptomatic thoracic disc herniations remain clinically silent on follow-up — only a small minority progress to become symptomatic
- Provides the evidence base for non-operative management of incidentally discovered thoracic disc herniations