What Are IDEM Tumours?
Intradural extramedullary (IDEM) tumours grow inside the covering of the spinal cord (the dura) but outside the cord itself. Most are benign — meningiomas, schwannomas, and neurofibromas — and press on the cord or nerve roots as they slowly enlarge. Surgery to remove them is often curative.
Arises from the dura, more common in women and in the thoracic spine.
Arises from a nerve root; sometimes extends through the nerve exit ("dumbbell" tumour).
Neurofibroma, myxopapillary ependymoma, and cysts are less common types inside the dura.
For symptoms and an overview of all spinal tumour types, see spinal tumours.
When Surgery Is Advised
Surgery is usually advised when an IDEM tumour causes symptoms — pain, numbness, weakness, unsteady walking, or bladder changes — or when it is growing and compressing the cord. A small tumour found by chance without symptoms may be watched with periodic MRI.
Observation suits small tumours without symptoms; removal suits tumours that cause symptoms or compress the cord — and for most IDEM tumours, removal can take the tumour out completely. The choice should follow the anatomy of your condition, your own circumstances — your health, your work, and what matters to you in recovery — and the advice of your neurosurgeon after examining you and reviewing your scans.
Rapidly worsening weakness or numbness in the legs, numbness rising up the body, or new loss of bladder or bowel control can mean the spinal cord is being compressed. Go to the nearest hospital emergency department without delay.
The Procedure: Step by Step
The microsurgical procedure is performed under general anaesthesia with specialized nerve monitoring:
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Anaesthesia and monitoring: Under general anaesthesia, with neurophysiological monitoring of the spinal cord and nerve roots.
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Exposure: A midline incision over the tumour level, confirmed by X-ray, and removal of the laminae over the tumour (or a smaller opening for small tumours).
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Opening the dura: Under the operating microscope.
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Removing the tumour: The tumour is separated from the cord and removed, often piece by piece from its centre. A meningioma's attachment to the dura is treated; for a schwannoma, the small nerve rootlet it arises from is usually divided after testing.
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Closure: Watertight closure of the dura, and the wound in layers. Fixation is rarely needed unless bone removal is extensive.
Risks to Discuss Before Surgery
Potential surgical risks to review with your neurosurgeon before the procedure include:
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Temporary worsening: Temporary worsening of numbness or weakness, which often improves.
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Spinal fluid leak: Spinal fluid leak from the dural closure.
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Recurrence: Uncommon after complete removal, more likely if part of the tumour had to be left.
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General surgical risks: Infection, bleeding, and the general risks of anaesthesia.
Recovery and Follow-up
Recovery follows a structured progression from early mobilization to ongoing rehabilitation and follow-up imaging:
Walking within a day or two; a hospital stay of a few days.
Pain usually improves early; numbness, strength, and walking continue to improve over weeks to months, helped by physiotherapy.
Follow-up MRI to confirm complete removal and watch for recurrence.
Questions to Ask Your Neurosurgeon
These are the questions patients most often search for before surgery for a meningioma or schwannoma of the spine:
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Tumour type: What type of IDEM tumour is it likely to be?
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Treatment timing: Does it need removal now, or can it be watched?
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Completeness of removal: Is complete removal likely?
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Nerve monitoring: Will nerve monitoring be used, and will any nerve rootlet need to be divided?
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Imaging schedule: How often will I need follow-up MRI?
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Cost estimate: What will the total cost be, and what does it include? Ask for a written estimate.
Unless there is an emergency, spine surgery is a planned decision. Seeking a second opinion from a qualified spine surgeon or neurosurgeon before deciding is entirely appropriate.
Frequently Asked Questions
General information only. Please consult a qualified spine surgeon or neurosurgeon for advice about your situation.
An IDEM (intradural extramedullary) tumour grows inside the dura, the covering of the spinal cord, but outside the cord itself. Most are benign, such as meningiomas, schwannomas, and neurofibromas.
Most spinal meningiomas are benign, slow-growing tumours. They cause symptoms by pressing on the spinal cord and are usually treated by surgical removal, which is often curative.
Yes, in most cases. A schwannoma arises from a nerve rootlet and can usually be removed completely; the rootlet it comes from is tested and usually divided, often without noticeable effect.
A growing meningioma can increasingly compress the spinal cord, causing worsening numbness, weakness, unsteady walking, and bladder problems. Small tumours without symptoms may be watched with MRI.
Most patients walk within a day or two and go home within a few days. Pain often improves early, while strength, sensation, and walking continue to improve over weeks to months.
IDEM tumours are removed by neurosurgeons using microsurgery and nerve monitoring. Dr Jaydev Panchawagh—MBBS (B.J. Medical College, Pune), MS in General Surgery (KEM Hospital, Pune), and MCh in Neurosurgery (Seth GS Medical College and KEM Hospital, Mumbai)—is a consultant neurosurgeon in Pune (102, Bhagyatara Society, Erandwane, Pune, Maharashtra 411004; Tel: +91-9011333841) with 27 years of neurosurgical practice who performs spinal meningioma and schwannoma surgery.
