Intradural Spinal Tumours

The spinal cord and the nerve roots that stream off it are enclosed within the dura, a strong membrane that contains the cerebrospinal fluid in which the cord floats. The word intradural simply means inside the dura. When a tumour is described as intradural, it is located within this sac, in close company with the cord or the nerve roots, rather than in the surrounding bone of the spinal column.

Two compartments are distinguished within the intradural space. The intradural-extramedullary compartment lies inside the dura but outside the spinal cord — the tumour sits alongside the cord or wrapped around a nerve root, pressing on the cord from the outside. The intramedullary compartment lies within the very substance of the spinal cord, so that the tumour grows among the delicate nerve fibres of the cord itself. This distinction shapes everything that follows.

Primary intraspinal tumours are uncommon, described with an incidence in the region of one per hundred thousand people per year. Intradural-extramedullary tumours make up roughly four-fifths of intradural tumours in adults, and around two-thirds in children. The most common members are the nerve sheath tumours — schwannomas and neurofibromas — and the meningiomas; in many series schwannomas and meningiomas together account for over half of all intradural-extramedullary lesions.

Intramedullary tumours, growing inside the cord, are rarer, comprising roughly a fifth to a third of primary spinal cord tumours. Within this group the gliomas predominate, chiefly ependymomas and astrocytomas, with haemangioblastomas forming most of the remainder. Ependymomas are relatively more common in adults and astrocytomas relatively more common in children.

Meningiomas arise from the arachnoid cap cells of the lining membranes of the cord near where the nerve roots leave. They are typically slow-growing and, in the spine, almost always benign. They show a strong predilection for the thoracic spine and a marked female predominance, and are encountered most often in middle and later life. Because a spinal meningioma grows inside the dura but outside the cord, its effect is one of gradual compression from the outside. On imaging a meningioma typically sits broadly against the dura, often with a so-called dural tail, and enhances after contrast.

The nerve sheath tumours — schwannomas and neurofibromas — arise from the cells that insulate the nerve roots. Schwannomas grow from Schwann cells and are typically well-defined tumours attached to a single nerve root; neurofibromas are more intimately bound up with the nerve fibres. Radicular pain — pain that radiates along the territory of the affected nerve — is the characteristic early feature. A schwannoma can sometimes grow partly inside the canal and partly outside it through a nerve exit foramen, taking on a dumbbell shape.

At the very bottom of the spinal canal, the myxopapillary ependymoma arises characteristically from the filum terminale and the region of the conus medullaris and cauda equina. Although ependymomas elsewhere grow within the cord, this variant typically presents as an intradural-extramedullary mass in the lower lumbar region. Under the 2021 World Health Organization classification it is graded as a grade 2 tumour, reflecting a recognised tendency to recur.

Ependymomas arise from the ependymal cells lining the central canal of the cord and are the most common intramedullary tumour in adults. They are typically slow-growing, tend to sit centrally within the cord, and characteristically have a relatively well-defined edge.

Astrocytomas arise from the astrocytes, the supporting glial cells of the cord, and are the most common intramedullary tumour in children. They are infiltrative, growing among the cord's nerve fibres without a clear boundary, which makes the interface between tumour and healthy cord far less distinct. Their behaviour is strongly governed by their WHO grade.

Haemangioblastomas are benign, highly vascular tumours that tend to lie towards the back of the cord and are often accompanied by a sizeable cyst or by swelling of the cord. They classically present with slowly progressive sensory disturbance, particularly affecting the sense of position and balance.

Most intradural tumours occur sporadically. A minority arise in the context of recognised genetic conditions: NF1 is associated particularly with neurofibromas; NF2-related schwannomatosis is characterised by schwannomas, meningiomas and spinal ependymomas; schwannomatosis describes the development of multiple schwannomas without the hallmark hearing-nerve tumours of NF2; and von Hippel-Lindau disease is the condition associated with haemangioblastomas, which in this setting are frequently multiple.

Because most enlarge gradually, the typical history is one of features evolving over months rather than suddenly. Pain is among the earliest and commonest features. As a tumour presses on or grows within the cord, it may give rise to altered sensation, weakness, unsteadiness of gait, or disturbance of bladder and bowel control. A proportion of intradural tumours are discovered incidentally on a scan carried out for an unrelated reason. The literature notes that a substantial share of incidentally detected meningiomas and schwannomas may never require treatment within a person's lifetime.

Magnetic resonance imaging is the key investigation. It is uniquely able to show the position of a tumour relative to the cord and nerve roots, define which compartment it occupies, demonstrate its size and margins, reveal associated cysts or cord swelling, and characterise how it enhances with contrast. MRI cannot, however, give a definitive tissue diagnosis; meningiomas and schwannomas share overlapping appearances, and the three common intramedullary tumours can be difficult to separate on imaging alone.

Surveillance is described for tumours that are small, asymptomatic and stable, particularly when found incidentally — serial MRI watching for growth or new symptoms. Microsurgical excision is the principal active treatment for symptomatic tumours and for those that grow or threaten the cord. For the benign extramedullary tumours, complete removal is the goal where it can be done safely, with good reported outcomes. For intramedullary tumours, ependymomas and haemangioblastomas are often amenable to complete removal, while infiltrative astrocytomas are handled more conservatively, with grade strongly influencing the approach. Intramedullary surgery is undertaken with the aid of microsurgical technique and intraoperative monitoring of the cord.

For most intradural spinal tumours the outlook is broadly reassuring. The benign extramedullary tumours and the well-defined ependymomas and haemangioblastomas are reported to do well after complete removal, with outcome closely tied to neurological function at the time of treatment. The infiltrative astrocytomas are the more variable group, their outlook governed above all by grade.

This page is general medical education and is not a substitute for individual advice. New or worsening weakness, numbness, saddle numbness, or any disturbance of bladder or bowel control requires urgent assessment.

• —Samartzis D et al. Intramedullary Spinal Cord Tumors Part I. Global Spine J 2015;5(5):425–435 (PMC4577312)
• —Soderlund KA et al. Intradural Extramedullary Spinal Neoplasms: Radiologic-Pathologic Correlation. RadioGraphics 2019;39(2):468–490
• —Extramedullary Intradural Spinal Tumors: A Review (PMC5655171)
• —WHO Classification of Tumours of the Central Nervous System, 5th ed. (2021) — myxopapillary ependymoma reclassified as grade 2
• —Spinal Cord Hemangioblastomas in von Hippel-Lindau Disease (PMC3481394)
• —Current Understanding of Neurofibromatosis Type 1, 2, and Schwannomatosis (PMC8198724)
• —Spinal Cord Ependymoma – Surgical Management and Outcome (PMC6454966)
• —Treatment, prognostic factors, and outcomes in spinal cord astrocytomas. Neuro-Oncology 2013 (PMC3607259)
• —Clinical features and prognostic factors in spinal meningioma surgery. Sci Rep 2021 (PMC8172892)
• —Intramedullary Spinal Cord Tumors. StatPearls (NBK442031)

This information is for general patient education and is not a substitute for an individual consultation. Always seek personalised advice from a qualified spinal specialist.