The spinal cord originates from the brain stem and runs in the spinal canal of the 24 vertebrae. It gives off nerves on both sides at the level of each vertebra - the spinal nerves. Just like the brain, the spinal cord is embedded in cerebrospinal fluid and surrounded by three tissue layers - the meninges.
Spinal tumors can occur in the spinal cord (intramedullary tumors) or arise from adjacent structures within in the spinal canal (extramedullary tumors). The most common spinal tumors are: spinal ependymoma, astrocytoma, haemangioblastoma, schwannoma (=neurinoma), meningioma and metastases. All tumour types have in common that neurological symptoms and deficits occur when nerve tracts of the spinal cord or spinal nerves are compressed. Typical symptoms are paralysis, sensory disturbances, gait instability, incontinence, disturbances of sexual functions and various types of pain. Since spinal tumors (apart from metastases) usually grow slowly, the symptoms develop insidiously. If left untreated, spinal tumors can eventually lead to paraplegia.
In addition to a careful neurological examination, high-resolution magnetic resonance imaging (MRI / MRI) is used to visualise spinal tumors and especially their borders and pressure effects in relation to neighbouring structures. In order to assess the bony structures and the stability of the spinal column, computer tomography (CT) and, if necessary, dynamic X-ray series are obtained.
The diagnosis of spinal canal stenosis is made by performing MRI and CT imaging of the lumbar spine in patients presenting with typical symptoms. This may show a slip of one vertebral body on the underlying one (spondylolisthesis), either forwards (ventro- or anterolisthesis) or backwards (retrolisthesis). This slippage can cause a narrowing of the canal and trap or stretch one or more nerve roots, causing pain and functional deficits.
In general, symptomatic tumors should be operated as soon as possible. This is especially true if a malignant tumour, such as a metastasis, is suspected. In the case of accidentally discovered, non-symptomatic tumors, which do not show any signs of aggressiveness in the MRI, it is possible to observe them with regular follow-up MRIs.
Spinal cord tumors arise from the tissue structures of the spinal cord. They usually grow slowly and the initial symptoms are subtle. The most common tumors of the spinal cord are ependymoma, astrocytoma and haemangioblastoma.
Ependymomas and haemangioblastomas are often surrounded by a defined tissue plane and can therefore usually be completely surgically removed. Astrocytomas show more diffuse growth with infiltration of surrounding nervous structures.
Before surgery, high-resolution MRI imaging is performed. DTI sequences may visualise the neighbouring neural pathways in three dimensions in order to be able to plan the surgical strategy. Whenever possible, a hemilaminectomy, rather than a full laminectomy, is performed. In this way, the ligaments and bone structures important for the stability of the spinal column (spinous processes, facet joint) are preserved.
Before the spinal cord is opened, the intramedullary tumour is visualised with ultrasound. The length and width of the hemilaminectomy can thus be precisely adjusted and the contour and echo structure of the still untouched tumour and spinal cord are inspected.
For deep lesions the spinal cord is usually opened exactly in the midline and the posterior cord tracts are separated from each other by blunt dissection. In the case of tumors that reach the surface, microsurgical dissection begins directly at the superficial boundary layer between the tumour and the spinal cord.
The microsurgical removal of a spinal cord tumour means precision work in the millimetre range and with the finest micro-instruments - similar to surgery of the brain or the brain stem. Through careful handlings of micro-instruments, the fine layer between the tumour and the spinal cord is identified under constant irrigation and high magnification. The tumour is exposed, reduced in size and finally removed. Especially in the case of diffusely growing tumors such as astrocytomas, permanent electrophysiological monitoring during the operation is of eminent importance. Special probes are used for this purpose and, in addition, impulses are constantly sent from the brain through the entire spinal cord and in turn from the limbs back to the brain. A dedicated team of neurologists is present in the operating theatre for this purpose.
For resection control, high-resolution ultrasound with fine probes is used, allowing visualizing the progress of resection and tumour remnants.
Extramedullary, intradural tumors do not grow in the spinal cord but originate from neighbouring tissue structures. The most common extramedullary intradural tumors are meningiomas and neurinomas.
Meningiomas are almost always benign (WHO I) and arise from the middle layer of the three meninges. They usually grow slowly, but over time, the tumour mass causes pressure on the spinal cord and/or the nerve roots of the spinal canal. Depending on the location, this leads to various neurological deficits such as paralysis, sensory disturbances and difficulties with bladder control. Respiratory disturbances may occur in case of tumors located very high in the spinal canal.
Spinal schwannomas or neurinomas develop from sheath cells of spinal nerves, the so-called Schwann cells. In comparison to meningiomas, neurinomas can be located both inside and outside the spinal meninges. They can grow along the nerve into the lateral opening of the spinal column (neuroforamen) and even beyond. On MRI, this growth typically resembles the shape of an hourglass.
Depending on the localisation and size of the schwannoma, sensory disturbances, paralysis and pain occur in the territory of the affected spinal nerve. With increasing size, like in the case of other tumors, the spinal cord will be compressed and severe deficits may occur.
Meningiomas and neurinomas / schwannomas are precisely visualised in a high-resolution MRI before surgery. CISS sequences show the neighbouring spinal nerves and thus provide an exact spatial understanding of the tumour.
Access to the tumour is usually possible via a tailored hemilaminectomy. Intra-operative imaging with ultrasound is carried out before the dura is opened, similar to the surgery for intramedullary tumors (see above). With careful microsurgical techniques meningiomas can usually be detached from the neural structures and completely removed. Meningiomas whose dural attachments extend anterior to the spinal cord are dissected minimally invasively with the help of an endoscope in order to avoid damaging the spinal cord.
In contrast to meningiomas, neurinomas / schwannomas often enclose a nerve fibre or an entire nerve root. Their individual functions are evaluated intra-operatively with highly sensitive electrophysiological probes and measurement. A neurological team is present in the operating theatre for this. Usually the slow tumour growth has already led to functional impairment of the affected nerve root and other unaffected nerve fibres have taken over its neurological function. In this case, the nerve carrying the tumour can be resected as part of the complete removal of the tumour. If, in rare cases, motor activity is detected in the nerve fibre adjacent to the tumour, the nerve is microsurgically dissected free of tumour and preserved, if necessary leaving behind small tumour residues.
In the case of thoracic schwannomas / neurinomas which grew far laterally beyond the neuroforamen, the extra-foraminal tumour part is removed endoscopically in collaboration with a thoracic surgery team (see case example).
Metastases are the most common extradural tumors, i.e. tumors that lie outside the meninges of the spinal cord. They often originate from lung, breast, kidney or prostate carcinomas and first affect the bony structures of the vertebral bodies. Occasionally, plasmocytomas, lymphomas, sarcomas and chondromas can also be found in the spine.
Metastases primarily cause back pain in the affected vertebral bodies, which often persists even when lying down and at night. They can grow into the spinal canal, increasingly narrowing it and exerting pressure on the spinal cord and spinal nerves. The result, as with other spinal tumors, is a variety of neurological deficits.
In principle, all tumors of the vertebral bodies can lead to instability and spontaneous fractures of the spinal column. The aim of the operation is therefore, in addition to decompression of the spinal cord and the nerve roots, stabilisation of the spinal column. This is individually adapted to the extent of the tumorous infiltration and often a vertebral body replacement or a stabilization (spondylodesis) of several segments is necessary. In our centre, these interventions are carried out in cooperation with a specialized orthopaedic team, especially taking into account the entire spinal column statics.
Metastases must be treated within the oncological context of the underlying disease and each case is discussed in our interdisciplinary tumour board before and after surgery.
52-year-old woman with diffuse neck and shoulder pain, dissociated sensory disturbances and progressive gait instability.
MRI revealed a mid-spinal cord contrast-enhancing lesion at level of C1. The suspected MRI diagnosis was ependymoma.
Surgery: resection of the C1 arch, dura opening, and electrophysiological and ultrasound-guided blunt dissection of the posterior midline of the spinal cord. Under constant electro-physiological monitoring, the tumour was completely removed with microsurgical techniques. Electrophysiological recordings remained completely normal during the entire surgery.
MRI after surgery showed no residual tumour and no evidence of damage to the spinal cord. Except for a mild, temporary numbness of the right leg, the patient was symptom-free and fully mobile after surgery. The wound healed without problems. After three years, the MRI still shows no signs of tumour recurrence and the spinal cord appears normal and healthy.
This 27-year-old woman underwent an x-ray due to breathing difficulties. A mass was detected, that later appeared on MRI to be a large spinal neurinoma originating from the right Th-3 nerve root. In addition to the intraspinal portions, the mass had grown through the neuroforamen into the thoracic cavity. There, the tumour had a maximum diameter of 7cm and revealed to be the cause of the respiratory symptoms.
The operation was performed together with a thoracic surgical team. First, the tumour in the spinal canal and neuroforamen was resected microsurgically via a hemilaminectomy. This this took pressure off the spinal cord. Meanwhile, the thoracic surgeons freed the tumour via a small thoracoscopic approach and removed it completely.
After the surgery, the respiratory symptoms resolved rapidly and the patient was neurologically asymptomatic. She was discharged after a few days. The wound healing was unremarkable. Post-operative MRI scans showed that the tumour had been completely removed. The MRI after four years also showed normal tissue structures without evidence of recurrence.