What is Conus and Cauda Equina Tumors?
Tumors found in the conus and cauda equina regions of the spinal canal are unique because of their specific locations. These areas are where the last part of the spinal cord, the conus medullaris, is found and where the nerve roots of the distal stem from. This is also where the centers for the body’s spinal bowel and bladder are located. The cauda equina is a bundle of nerve roots for the lower part of your spine. The conus and cauda equina are a bridge between the central and peripheral nervous systems. The conus primarily affects central functions, while the cauda impacts peripheral functions. Since they are closely located, a problem in one could affect the other. Specific deficits give rise to conditions called cauda equina syndrome (CES) and conus medullary syndrome (CMS). The tumors causing these syndromes are studied here.
Primary tumors originating directly in the spinal cord are not as common as metastatic spinal tumors, which start elsewhere in the body and then spread to the spine. Spinal canal tumors are categorized based on where they are found: outside the protective covering of the brain and spinal cord (extra-dural), inside this covering but outside the neural tissue (intra-dural/extra-medullary), or within both the covering and the neural tissue (intra-dural/intra-medullary).
Tumors in the lower spine can affect either the vertebrae (backbones), the distal end of the spinal cord (conus medullaris), or the nerve roots (cauda equina). They can start there or spread from other parts of the body, and they can be either benign (not cancerous) or malignant (cancerous). Tumors can present in different ways, but the most common ones in the backbones are metastatic, meaning they spread from elsewhere in the body. The most common tumors in the conus medullaris are ependymoma and astrocytoma. Metastatic tumors in the conus medullaris are rare. The most common tumor in the cauda equina is a schwannoma.
What Causes Conus and Cauda Equina Tumors?
Tumors that occur in the spinal bones are often secondary cancers that have spread from other areas, such as the lung, breast, prostate, or kidney. There are, however, some less common tumors that originate from the bones or cartilage in the spine. There can also be tumors within the lower end of the spinal cord. These can develop from the star-shaped brain cells (astrocytes), leading to a type called astrocytoma, or from the lining of the spinal cord’s central canal, causing ependymoma. These types of secondary tumors are not very frequent.
In the group of nerves at the end of the spinal cord, known as the cauda equina, tumors often develop from cells that wrap around the nerve roots (schwann cells), causing a type called schwannoma. They sometimes grow in a particular pattern that’s likened to a dumbbell as they expand out of the openings where the nerves exit the spine. Tumors can also form from nerve root tissue, known as neurofibroma, or may be an unrelated benign growth, called a meningioma. This tumor forms within the protective coverings of the brain and spinal cord and could occur anywhere along the lower spine, pressing against nerve roots or the lower end of the spinal cord. They originate from specific cells of the arachnoid layer, one of the three layers of tissue that protect the brain and spinal cord and are surrounded by a tail-like extension of tissue.
There are a variety of causes for conditions like cauda equina syndrome (CES) and conus medullaris syndrome (CMS), which occur when the group of nerves at the end of the spinal cord or the lower end of the spinal cord itself are affected. These conditions need to be considered when diagnosing tumors in these areas.
CES has many potential causes including:
– Pressure from a severely herniated disc, tumor, trauma or blood clot in the spine
– Infection: typically from a spinal abscess that’s made worse by inflammation of the disc or bone infection
– Reduced blood flow
– Inflammation
– The narrowing of the spinal canal, known as spinal stenosis
– Post-surgery complications in the lower spine
CMS can also be caused by several factors including:
– Pressure from a tumor, trauma, or blood clot. A type of tumor specific to this area is known as myxopapillary ependymoma and it can cause bleeding within the tumor
– Infection: similar to CES, an abscess complicated by discitis or bone infection
– Reduced blood flow to the area
– Inflammation
Risk Factors and Frequency for Conus and Cauda Equina Tumors
Cauda equina syndrome and conus medullaris syndrome are uncommon conditions, affecting 1 to 3 out of every 100,000 people each year. Out of all lumbar disc conditions requiring surgery, 1 to 2 percent present with cauda equina syndrome.
Regarding spinal lesions, about 55% are extradural and affect the vertebral column, with 20% found in the lumbar spine. The most frequently encountered lesion is metastasis. A further 40% of spinal lesions are intradural extramedullary, typically meningiomas of the dural sac or schwannomas and neurofibromas of the nerve roots. Only 5% of spinal lesions are intramedullary, with more than 90% being ependymoma or astrocytoma of different histological grades and less than 2% being metastases.
- Cauda equina syndrome and conus medullaris syndrome are rare, impacting 1 to 3 out of 100,000 people each year.
- About 1-2% of lumbar disc surgeries are a result of cauda equina syndrome.
- About 55% of spinal lesions are extradural and affect the vertebral column, with 20% occurring in the lumbar spine.
- Metastasis is the most common type of lesion.
- About 40% of spinal lesions are intradural extramedullary, mainly consisting of meningiomas, schwannomas, and neurofibromas.
- Only 5% of spinal lesions are intramedullary, with over 90% being either ependymoma or astrocytoma, and less than 2% are metastases.
Signs and Symptoms of Conus and Cauda Equina Tumors
When patients have issues with their back, it can present in a few ways, such as back pain, radiculopathy, or myelopathy. These symptoms are usually linked to nerve compression. People with metastatic disease often have additional symptoms like weight loss, general malaise, night sweats, or a history of cancer. Patients may also experience symptoms like numbness or tingling in the lower extremities over time, or have reduced sensation in the perineal and perianal areas, also known as “saddle anesthesia”. It’s also common to see upper or lower motor neuron findings and incontinence. The anal sphincter tone is diminished, and deep tendon reflexes may be weakened in the lower extremities. The presence of these symptoms is often gradual, which can lead to delays in diagnosis. Sexual dysfunction can also occur.
- Back pain, radiculopathy, or myelopathy
- Weight loss, general malaise, night sweats
- Manifestation of numbness or tingling in the lower extremities
- “Saddle anesthesia” or reduced sensation in the perineal and perianal areas
- Upper or lower motor neuron findings
- Bowel/Bladder incontinence
- Diminished anal sphincter tone
- Reduced deep tendon reflexes in the lower extremities
- Potential sexual dysfunction
There are some distinguishing features of CES (Cauda equina syndrome) and CMS (Conus medullaris syndrome):
- Onset: gradual and one-sided in CES; sudden and affecting both sides in CMS
- Pain: severe and radiating in CES; rare, affecting both perineum and thighs in CMS
- Sensory: saddle anesthesia in both; one-sided in CES; affecting both sides in CMS
- Motor function: pronounced and one-sided in CES; mild and affecting both sides in CMS
- Reflex: only ankle jerk is absent in CES; both ankle jerk and knee jerk may be absent in CMS
- Autonomic: Bladder dysfunction and impotence occur later in CES; occur early in CMS
Testing for Conus and Cauda Equina Tumors
In simple terms, if a patient has back pain but no neurological issues, and they don’t have any major risk factors, a basic evaluation of their condition should suffice. However, if there are significant risk factors present, further examination using neuroimaging technology will be necessary. If the patient shows signs of neurological problems or loss of bowel or bladder control, it will be important to use Magnetic Resonance Imaging, or MRI, to check for potential mass lesions.
MRI is the best method for assessing nontraumatic spinal lesions. If there’s a possibility that the patient has a mass lesion due to metastasis, or the spread of cancer, the evaluation should include a scan of the chest, abdomen, and pelvis using Computed Tomography, or a CT scan. Alternatively, a full-body Positron Emission Tomography or PET scan can also be used to check for the original cancer site.
Lower back X-rays may show signs of fractures, damaged pedicles (which are small, stubby projections on the vertebral bones), abnormal angulation (bending), or enlarged neural foramina, which are the small openings through which nerves and blood vessels pass. If necessary, a CT scan can also be used to see a detailed view of the bony structure of the spine.
Treatment Options for Conus and Cauda Equina Tumors
Patients suffering from inflammation or tumors can benefit from anti-inflammatory medications and steroids. When surgical intervention becomes necessary, the main goals are to relieve pressure on the nerves, remove as much of the tumor as possible, and stabilize the spine if it’s unstable. The ideal approach to treatment usually involves experts from multiple disciplines and considers the patient’s long-term prognosis and any other necessary treatments.
Certain types of benign tumors, like schwannomas and meningiomas, usually don’t require immediate treatment unless they’re causing symptoms or are large. In these instances, surgery to remove the tumor and relieve nerve pressure should be attempted. If the tumors are cancerous, radiation or chemotherapy may be needed.
In the case of two specific cancer types, astrocytoma or ependymoma, surgery is recommended as the initial treatment. The use and timing of chemotherapy and radiation, however, is still debatable. These treatment options depend on the type of tumor, its grade, and how much was removed during surgery.
In cases of metastatic lesions – where cancer has spread inside the body – the treatment options of surgery, radiation, and chemotherapy are more complicated and need a team of experts to decide. Fully removing these lesions can be tough, and trying to do so could worsen the patient’s neurological symptoms.
Patients with disease spread should ideally have the disease controlled across their entire body. If it’s known where the cancer started, surgery is generally avoided to prevent worsening symptoms. However, if the original source of cancer isn’t known, a biopsy is required.
During the period around surgery, measures should be taken to prevent deep vein thrombosis or pulmonary embolism, which are blood clots that can form in the legs or lungs.
What else can Conus and Cauda Equina Tumors be?
When a doctor is evaluating a patient with tumors in the lower part of the spine (known as conus or cauda equina tumors), there are a number of other conditions that they need to consider as well. These conditions could also cause similar symptoms and include:
- Astrocytoma (a type of brain tumor)
- Ependymoma (a type of spinal tumor)
- Myxopapillary ependymoma (another type of spinal tumor)
- Metastases (a condition where cancer spreads from one part of the body to another)
- Herniated disc (when the disc between the bones in your spine bulges out of place)
- Transverse myelitis (a spinal cord disorder causing weakness and numbness)
- Spinal arteriovenous malformation (an abnormal tangle of blood vessels in the spine)
- Spinal cord infarct (when there’s a lack of blood flow to the spine causing tissue death)
- Multiple sclerosis (a disease affecting the brain and spinal cord)
- Diabetic neuropathy (nerve damage resulting from high blood sugar)
- Guillain-Barré syndrome (a nerve disorder causing weakness and tingling)
- Amyotrophic lateral sclerosis (a nervous system disease affecting muscle movement)
- Sarcoidosis (a disease causing small patches of red and swollen tissue to develop in organs)
Remember, doctors make these considerations to ensure they arrive at an accurate diagnosis.
What to expect with Conus and Cauda Equina Tumors
The outcome for a patient can depend on the type and severity of the disease as well as their neurological health before surgery. The sooner the surgical decompression is performed, the better the outcome. The best outcomes have been seen with surgery within the first 48 hours of symptom onset. Some studies also suggest benefits if surgery is performed within the first 72 hours.
However, issues with bladder function presents a negative influence for patient outcome. Recovery of bladder function is typically seen in about half of the patients with this condition.
Possible Complications When Diagnosed with Conus and Cauda Equina Tumors
Tumors in the conus and cauda equina areas can cause complications, and so can the methods used to treat these tumors. The complications can be quite varied, and they include:
- Neurological issues ranging from mild weakness to paralysis
- Problems controlling urination
- Difficulty controlling bowel movements
- Problems with sexual function
- Numbness in the saddle area (region of the body in contact with the seat when sitting)
- Pain that follows the path of a nerve
- Conditions worsening after surgery, which can include:
- New neurological problems
- Infections
- Leakage of cerebrospinal fluid, which is the liquid that surrounds the brain and spinal cord
Preventing Conus and Cauda Equina Tumors
It’s crucial that patients understand their diagnosis and treatment plan so they can make informed decisions about their health. This understanding can directly impact their health outcomes. After the medical testing is done, patients should be told about their results and potential future treatments such as radiotherapy and chemotherapy.
Patients also need to be educated on how to deal with ongoing health issues. This requires a team of various health professionals including medical, physical, psychological, educational, vocational, and social experts. By working together, this team can help patients improve in all areas of their life and health.
