What is Intramedullary Spinal Cord Tumors?
Spinal tumors are a type of growth in your nervous system, making up about 15% of all such issues. Generally, these tumors aren’t cancerous, and they cause problems mostly by putting pressure on your spine and nerves. There are three main types of spinal tumors, and they’re categorized based on where they’re located in your spine – extradural, intradural-extramedullary, and intramedullary.
Extradural tumors are the most common type. They’re found on the vertebrae, which are the bones of your spine, or on structures outside the dura, which is a protective covering. These tumors often spread to other parts of the body. The second most common type, intradural extramedullary tumors, start from the leptomeninges (thin layers that cover the brain and the spinal cord) or nerve roots. These tumors are located inside the dura but outside of the spinal cord and include conditions such as meningiomas or neurofibromas.
The least common type is intramedullary spinal cord tumors, making up between 20 to 30% of all primary intradural tumors, and only 2 to 5% of all spinal tumors. These tumors start within the spinal cord tissue, often from a type of cell called glial cells. These tumors can invade and damage gray and white matter, which are types of nerve tissues in your brain and spinal cord. Ependymomas and astrocytomas are the most common types of this tumor, followed by hemangioblastomas. There can also be other types, such as lipomas, germ cell tumors, gangliogliomas, germinomas, lymphomas, and metastases.
What Causes Intramedullary Spinal Cord Tumors?
Spinal cord tumors that are found inside the spinal cord (called intramedullary spinal cord tumors) are usually random occurrences. However, sometimes these tumors are linked to certain health conditions like neurofibromatosis 1 or 2 (NF-1, NF-2) and Von Hippel-Lindau disease.
NF-1 is a condition caused by a change in a specific gene on chromosome 17, which normally protects the body from tumors. This change makes someone more prone to getting tumors, and about 19% of people with NF-1 may develop a spinal cord tumor. These tumors are mostly present as neurofibromas, which are the tumors of the nerve tissue, and are usually found within the protective covering of the spinal cord but outside the actual spinal cord itself.
NF-2, on the other hand, is caused by a change in a different tumor-suppression gene located on chromosome 22, and it’s seen in about 2% of patients with intramedullary spinal cord tumors. This condition commonly leads to a type of tumor called ependymomas and sometimes another one called meningiomas, which are extramedullary or found outside the spinal cord.
Meanwhile, in people with Von Hippel-Lindau disease, the most common type of intramedullary spinal cord tumor is a hemangioblastoma. This type of tumor begins in the blood vessels of the brain, spinal cord, or retina.
Overall, however, the most common type of intramedullary spinal cord tumor is an astrocytoma, which is a tumor that forms in the star-shaped cells in the brain and spinal cord.
Risk Factors and Frequency for Intramedullary Spinal Cord Tumors
Most (about 80%) tumors inside the spinal cord (intramedullary spinal cord tumors) are a type of tumor called “gliomas.” There are two main subtypes of gliomas, known as astrocytomas and ependymomas. Astrocytomas generally show up more in children who have spinal cord tumors, while ependymomas are typically found in adults who have spinal cord tumors.
- The most common place for these tumors to occur is in the cervical spine, or the neck (33% of cases).
- The thoracic region, or upper back, follows next (26% of cases).
- The lumbar region, or lower back, is the third most common area (24% of cases).
Kids often have more severe tumors than adults. In some cases (up to 20%), these tumors can cause a condition known as a syrinx, due to their ability to infiltrate and expand.
Astrocytomas in adults generally show up between the ages of 30 to 50. They’re usually lower-grade, meaning they’re less severe, and they’re most often found in the upper back. Ependymomas are usually found in the lower spinal cord and tailbone area. Men are slightly more likely to get them than women, and they generally occur between the ages of 30 to 60.
The third most common type of tumor within the spinal cord is called a hemangioblastoma. This type makes up about 2% to 15% of all spinal cord tumors.
It’s pretty rare for spinal cord tumors to spread from other places. When they do, they often start in the lungs or breast.
Signs and Symptoms of Intramedullary Spinal Cord Tumors
Intramedullary spinal cord tumors are often symptomless for a long time. Usually, the first symptom noted by patients is pain, which can be spread out or located along a nerve pathway. This pain often gets worse at night when the person is lying down. If the area of pain doesn’t match that of a slipped disc, a spinal cord tumor might be the cause. The pain can also be focused, leading to stiffness in the neck or back and can be felt as a bilateral burning sensation.
The next most common symptoms patients report are abnormal skin sensations such as tingling or numbness, followed by problems with movement. These may include weakness, clumsiness, lack of coordination, muscle shrinkage, twitching, irregular muscle contractions, and lessened deep tendon reflexes. In the advanced stages, the disease can cause loss of bowel or bladder control, resulting in either retention or leakage of urine or feces, or even impotence. Children might have nonspecific complaints, such as problems with their gait, misconstrued as just being clumsy. Any delay in motor development milestones should also be taken into account. Around 30% of these patients may show symptoms of scoliosis.
Doctors use the McCormick scale to assess the condition of patients with intramedullary spinal cord tumors:
- Grade I: Patients have normal neurological function with some mild focal deficits that do not significantly affect limb function. Spasticity or muscle stiffness is mild or absent, reflex abnormalities are minor, and there are no noticeable gait difficulties.
- Grade II: Sensory and motor deficits are present that affect function. Gait difficulties can range from mild to moderate, and pain affects the patient’s quality of life. However, patients can still function and walk independently.
- Grade III: Sensory and motor deficits are more severe than in Grade II. Patients require bracing or other assistive devices to function, and the level of their functional independence varies.
- Grade IV: Severe sensory and motor impairments require bracing or a wheelchair for movement. These patients are typically not functionally independent and need help with daily activities.
Testing for Intramedullary Spinal Cord Tumors
If your doctor suspects that you might have a spinal cord tumor, then a specific type of test called an MRI scan is considered the best method for revealing it. This scan can show the size and location of the tumor, how long it is, the surrounding swelling, and any cysts or fluid-filled cavities linked with the tumor.
There are three main types of internal spinal cord tumors, and even though they each appear in a specific way on these scans, it’s challenging to tell them apart using only this method. Two of these types are ependymomas and astrocytomas. They usually appear spread out over multiple spinal segments and light up with contrast; a substance given before the scan that helps to highlight the tumor structures. On certain types of scans, they usually look lighter or of similar intensity to the spinal cord but look brighter on other types of scans.
Ependymomas are often found in the center of the spinal cord and result in symmetrical widening of the cord. They usually light up uniformly with a clear border on imaging. Astrocytomas, on the other hand, usually don’t have a clear border and may not light up or have a light-up nodule or large fluid-filled cavity. Both types can have blood leak into them, but it’s more common in ependymomas.
The third type is a tumor called hemangioblastoma. Compared to ependymomas or astrocytomas, their enhancement pattern is more uniform. They also tend to have rounded nodules, can be associated with fluid-filled cavities, and can show significant surrounding swelling. As they are highly rich in blood vessels, another test called spinal angiography can be used to visualize the blood vessels feeding the tumor, which can assist in planning for a procedure to block the blood supply to the tumor before surgical removal.
Treatment Options for Intramedullary Spinal Cord Tumors
Surgery to remove tumors inside the spinal cord should ideally be performed as soon as they are diagnosed. This is because the sooner the surgery, the better the results tend to be. Delaying treatment could lead to further neurological issues – problems related to the brain and nerves – some of which may be irreversible.
The main purposes of having surgery are to find out what kind of tumor it is, remove as much of the tumor as is safely possible without causing neurological damage, and improve the function of the nervous system.
During the operation, doctors monitor the patient’s brain and nerve activity to help guide the surgery and detect any changes in neurological function. This ensures that they can detect and manage any potential issues promptly. How much of the tumor doctors can remove successfully usually depends on whether there’s a clear boundary between the tumor and healthy spinal cord tissue.
Low-grade astrocytomas – a kind of non-capsulated, infiltrating tumors – might be completely removed if a boundary can be found between the tumor and healthy tissue. In contrast, high-grade astrocytomas (more aggressive type) or low-grade astrocytomas that can’t be easily separated from spinal cord tissue may necessitate a procedure called a “subtotal safe resection.” Here, a biopsy is taken and then as much of the tumor is removed as safely possible. In these cases, removing the entire tumor aggressively could result in significant neurological problems. Additional targeted post-operative radiotherapy can be applied to manage any remaining tumor.
Ependymomas, on the other hand, are usually benign (not cancerous) and have a clear boundary with healthy spinal cord tissue, which makes it easier to remove them completely. In fact, total resection is possible in more than 90% of cases. The chance of their recurrence largely depends on how much of the tumor is resected.
Hemangioblastomas, tumors that are rich in blood vessels, can also often be resected and preoperative procedures can help reduce their high blood supply. Complete removal of such tumors is possible in approximately 83% to 92% of patients, with noticeable improvements in symptoms following the resection.
Patients who undergo intramedullary spinal cord tumor resection generally have better long-term outcomes when the operation is carried out sooner, and when they have fewer neurological issues before the surgery. The chance of their tumor coming back depends on how much of the tumor was removed and the type of tumor they had. Supplementary treatments including radiotherapy and chemotherapy are often used if the tumor comes back, for aggressive kinds of tumors, or when a complete resection isn’t advisable.
It’s clear that more research is needed to develop new treatments to improve patient outcomes, especially for astrocytomas, where clear boundaries for surgical removal often aren’t present.
What else can Intramedullary Spinal Cord Tumors be?
When doctors need to diagnose tumors in the spinal cord, they have to consider several possibilities. These include:
- Benign lesions, such as epidermoid cyst and lipoma
- Glial tumors, which can be ependymoma, myxopapillary ependymoma, astrocytoma, or ganglioglioma
- Non-glial tumors, like hemangioblastoma, metastasis, lymphoma in the central nervous system, multiple sclerosis, neuromyelitis optica, and meningioma
What to expect with Intramedullary Spinal Cord Tumors
The outcome for patients with spinal cord tumors located inside the spinal cord can often be uncertain. Before surgery, the patient’s neurological function – which relates to the health and function of their nerves – may provide key details about how successful their surgery might be. Unfortunately, patients with metastatic disease, a condition where the cancer has spread to other parts of the body, rarely live beyond 12 months.
Possible Complications When Diagnosed with Intramedullary Spinal Cord Tumors
Complications from spinal cord tumors that grow inside the spinal cord, also known as intramedullary spinal cord tumors, can include:
- Paralysis or weakness
- Sensory loss like numbness, tingling, and a sensation of pins and needles
- Involuntary release of urine or bowel, or both
- Problems associated with extensive bed rest such as deep vein thrombosis (blood clots), bedsores, lungs deflating (atelectasis), and physical weakening
- Sprouting of the tumor
- Death
Remember, it is important to monitor any changes and symptoms closely and to keep regular appointments with your healthcare provider.
Preventing Intramedullary Spinal Cord Tumors
Patients diagnosed with tumors in the spinal cord should receive a clear explanation about their illness and the expected impact on their movement and nervous system. How well a patient is doing before the surgery often affects the results. It is critical to get physical and occupational therapy evaluations and treatment soon after surgery to aid with the best recovery possible.
Depending on how deeply the tumor has spread, doctors might not be able to remove it completely without harming healthy spinal cord tissue. In such scenarios, additional treatments like radiation therapy may be needed after surgery to handle any remaining tumor. It’s crucial for patients and their families to have a full understanding of what to expect before and after surgery, which is why open and clear communication is vital.
