Thoracic Decompression

Thoracic myelopathy develops when the spinal cord in the mid-back is compressed — commonly by ossification of the ligamentum flavum (where the ligament at the back of the canal turns to bone), sometimes by ossification of the posterior longitudinal ligament, disc problems, or a combination. Because the thoracic cord has a relatively precarious blood supply and the canal is tight, compression here can cause progressive weakness and numbness in the legs, and difficulty walking. Where this is significant or progressive, decompressing the cord can be considered to protect and improve function.

For compression coming from behind — most typically ossification of the ligamentum flavum — decompression is usually carried out from the back, removing the bony arches and the ossified ligament to free the cord. Where compression comes from the front, an approach from the front or side may be needed instead, similar to that used for thoracic disc surgery. Because the thoracic cord is sensitive, the decompression is performed carefully to avoid disturbing it. Where significant bone is removed or the segment is destabilised, a fusion with screws and rods may be added to maintain stability and alignment.

Thoracic decompression can be considered for thoracic myelopathy from canal narrowing, especially ossification of the ligamentum flavum, where symptoms are significant or progressing. The approach — posterior for compression from behind, anterior or lateral for compression from the front — is chosen according to where the compression lies. Because outcomes depend partly on how long and how severe the compression has been, timely assessment matters. The decision, and the specific technique, are individualised to the pattern of compression and the person.

The evidence supports decompression for thoracic myelopathy while being honest about its challenges. Systematic reviews of surgical procedures for thoracic myelopathy, and studies of surgery for ossification of the ligamentum flavum, report that decompression can halt progression and improve function in many patients, with results influenced by the severity and duration of compression and the pattern of disease. The literature also documents that thoracic decompression can be technically demanding with a recognised complication profile. The balanced view is that it is an effective, worthwhile treatment for significant thoracic cord compression, carried out with careful planning and, where needed, stabilisation.

The operation is performed under general anaesthetic, usually with a hospital stay of several days. The main aim is to relieve pressure on the cord; improvement in leg strength, sensation and walking can occur gradually over months, though the degree depends on how long and how severe the compression has been. Where a fusion is added, the spine is held stable while it consolidates. Rehabilitation supports recovery. As with any operation there are risks, which are discussed fully beforehand. The best approach for a given person is decided together.

• —Zhu S, et al. A systematic review of surgical procedures on thoracic myelopathy. J Orthop Surg Res 2020. (PMID 33302988)
• —Ando K, et al. A systematic review of complications in thoracic spine surgery for ossification of ligamentum flavum. Eur Spine J 2018. (PMID 29284792)
• —Aizawa T, et al. Thoracic myelopathy caused by ossification of the ligamentum flavum: clinical features and surgical results. J Neurosurg Spine 2006. (PMID 17176015)
• —Sun X, et al. Surgical results and prognostic factors for thoracic myelopathy caused by ossification of ligamentum flavum: posterior laminectomy. Acta Neurochir 2013. (PMID 23584336)