Meningiomas and Neurofibromas in the spine are benign tumours which occur outside the spinal cord and cause symptoms mostly from causing pressure on the nerves or the spinal cord depending upon the level of tumour. These are Intra-dural extra medullary tumours in location and are called IDEM tumours in a shorter form in the medical fraternity. The word ‘intra-dural’ refers to being inside the duramater, which is the outermost layer covering the spinal cord and nerves inside the bones of spine. The word ‘extra-medullary’ refers to being outside the spinal cord. IDEM tumours represent almost two thirds of all primary spinal tumours.
What are spinal meningiomas?
Spinal meningiomas are very slow growing, non cancerous tumours of the spine. Meningiomas also occur in the brain as well. Spinal meningiomas are only 6-10 percent of all meningiomas of brain and spine put together. Spinal meningiomas as all meningiomas, are slightly more common in females and occur in the middle years of life.
Spinal meningiomas occur more commonly in the thoracic spine, followed by the cervical spine and least often occur in the lumbar spine. Meningiomas arise from cells called ‘Arachnoid cap cells’ and they grow slowly with invading the surrounding nerves and cause pressure effects on them.
Spinal meningiomas mostly present with pain at the site of tumour. Difficulty in walking, stiffness in legs, imbalance while walking, numbness in legs and difficulty in passing urine are the other common presenting complaints in patients with these tumours.
What are spinal Neurofibromas?
Spinal neurofibromas , also known as spinal schwannomas are another slow growing class of nan-cancerous tumours of the spine. These tumours are also called Nerve sheath tumours as these arise from covering layer of the nerves. Neurofibromas are common in patients with Neurofibromatosis type 1, which is a congenital disorder. These slow growing tumours present with similar complaints as spinal meningiomas. Unlike meningiomas, neurofibromas tend to grow along the nerve roots and come out of the spinal canal through the foramen and assume a characteristic shape like a “ dumbbell” across the bony boundaries of the neural foramen.
It may be difficult to differentiate between meningiomas and neurofibromas on MRI before the surgery.
What is the treatment of Spinal tumours like Meningioma and Neurofibromas?
The tumours on clinical presentation are big enough to cause pressure on the spinal cord or nerves. Therefore, surgery for excision of these tumours is the only way to reduce the pressure from the normal structures. Surgery aims at removing the tumour completely, reduce pressure on the critical nerves or cord, and to obtain tissue to ascertain nature of tumour. Depending upon the location of tumour in relation to the spinal cord it may not be technically feasible to remove the tumours completely especially in tumours anterior to the spinal cord. For such tumours Stereotactic radio surgery or SRS hold promise in reducing the rate of growth of tumours remaining after surgery. Small remaining tumours can be treated with this modality which uses computer guided radiation rays in a very precise directed manner to the tumour. This helps in shrinking the tumour and reducing the chances of tumour growth in future.
How is the spinal tumour surgery performed for such tumours?
Traditionally the surgery is carried out thought an incision over the back directly at the level of the tumour. The bone is exposed and bony lamina which covers the spinal canal is removed preserving the joints between the adjacent spinal vertebra. Then comes the Duramater which is opened using a share knife and tumour is identified. Tumour is removed using certain special instruments like an ultrasonic aspirator which fractures the tumour into small fragments and then sucks them out, under microscopic magnification. The aim is to remove tumour completely. However a small tumour may be left behind if it is deemed too risky to be removed.
Nowadays, minimally invasive spine surgery for spinal tumours is catching up. Smaller tumours which are outside the spinal cord like meningiomas and neurofibromas can be removed through minimally invasive spine surgery techniques. The benefits are shortened hospital stay, less blood loss, less pain and faster recovery.
See video for a Spinal tumour surgery in a minimally invasive fashion for a spinal neurofibroma at L5 level.
What are the complications of Spinal tumour surgery?
Spinal tumour surgery is a complex surgery. Despite the best of facilities and best of surgeons, some complications may not be avoidable. One such complication is infection. Infection is quite rare in primary spine surgeries. Other rare but dreaded complications include increase in neurological deficits like weakness in legs, arms or loss of urinary control. The complications depend a lot on the degree of compression of the spinal cord at time of surgery, surgical technique and site of tumour. Thoracic spine tumour surgery has maximum chances of surgery associated complications because of the smaller diameter of the bony spinal canal and precarious blood supply of the thoracic spinal cord.
How is the recovery after Spinal tumour surgery for Meningiomas and schwannomas?
Recovery time depends upon a lot of factors like the functional status of the patient before the surgery and degree of weakness.
In patients with mild to moderate deficits, recovery starts from day one of the surgery as most patients start feeling better. Feelings of heaviness and stiffness are the first to improve. Improvement in the power of muscles takes longer, and so do sensory symptoms. Pain associated with such tumours goes away and pain from the surgery scar goes in a couple of weeks.
In patients with very severe deficits, or who are bedridden before the surgery, recovery may be significantly prolonged.