Extramedullary tumors are growths that develop outside the spinal cord itself but within the spinal canal. These growths can be either non-cancerous (benign) or cancerous (malignant). Their characteristics often depend on their specific location and cellular origin.
Understanding Their Location
The spinal canal houses the spinal cord and is protected by a tough outer membrane called the dura mater. Extramedullary tumors are classified based on their precise position relative to this membrane, leading to two primary categories: intradural-extramedullary and extradural. This anatomical distinction is fundamental to understanding how these tumors might affect the nervous system.
Intradural-extramedullary tumors are situated inside the dura mater but remain outside the spinal cord tissue itself. They grow within the cerebrospinal fluid (CSF) space, which surrounds the spinal cord. As these tumors enlarge, they can press against the spinal cord or the nerve roots that branch off it.
Extradural tumors, in contrast, are located outside the dura mater, often residing in the epidural space. This space contains fat and blood vessels, and it is a common site for tumors that have spread from other parts of the body. Extradural tumors can also arise from the vertebral bones or surrounding tissues.
Common Types of Extramedullary Tumors
A variety of tumors can develop in the extramedullary space, with specific types being more common depending on whether they are intradural-extramedullary or extradural. The origin of these growths influences their behavior and typical characteristics.
Among intradural-extramedullary tumors, meningiomas and schwannomas are common. Meningiomas originate from the meninges, the protective membranes that envelop the brain and spinal cord, and are often benign. Schwannomas, also known as nerve sheath tumors, arise from the Schwann cells that support and insulate nerve cells, and are usually benign, though some can be malignant. Neurofibromas, another type of nerve sheath tumor, also develop along nerve cells and are often benign.
Extradural tumors are most often metastatic, meaning they have spread from a primary cancer elsewhere in the body. Common primary cancers that metastasize to the spine include those of the lung, breast, prostate, and kidney. Lymphomas, a type of cancer affecting the immune system, can also manifest as extradural spinal tumors. These metastatic tumors often involve the vertebral bodies before potentially compressing the spinal cord.
Recognizing Potential Symptoms
Extramedullary tumors can cause a range of symptoms. The specific symptoms often depend on the tumor’s location along the spine and its rate of growth.
Pain is a common initial symptom, often localized to the back or neck at the level of the tumor. This pain can worsen at night or with activities that increase pressure within the spinal canal, such as straining or coughing. The pain may also radiate along the path of a compressed nerve root, leading to what is known as radiculopathy, which can cause discomfort in the arms or legs.
Sensory disturbances are common, including numbness, tingling, or a burning sensation in the limbs. As the tumor grows, motor weakness can develop, making walking difficult or affecting coordination in the arms and legs. In more advanced cases, pressure on the spinal cord can lead to issues with bowel or bladder control, such as urinary retention or incontinence. Symptoms often progress slowly over months or even years, making early diagnosis challenging.
Diagnosis and Treatment Strategies
Identifying extramedullary tumors involves a thorough clinical assessment followed by specialized imaging. The diagnostic process begins with a detailed patient history and a neurological examination.
Magnetic Resonance Imaging (MRI) is the most effective imaging technique for diagnosing these tumors, offering detailed views of the tumor, its relationship to the spinal cord, and any associated compression or swelling. Computed Tomography (CT) scans can supplement MRI by providing clearer images of bone involvement and calcifications within the tumor. In some instances, a biopsy is performed to confirm the tumor type and guide treatment.
Treatment strategies for extramedullary tumors are tailored to the tumor type, size, location, and the patient’s overall health. Surgical removal is often the primary treatment, aiming to relieve pressure on the spinal cord and nerve roots and remove as much of the tumor as safely possible. While complete removal is the goal, it is not always feasible, especially for larger or more complex tumors.
Radiation therapy may be used when surgical removal is not possible, for any remaining tumor after surgery, or for metastatic tumors. This treatment delivers focused energy to shrink the tumor or control its growth. Chemotherapy is less commonly used for primary extramedullary tumors but can be an option for metastatic cancers or lymphomas. For small tumors that are not causing symptoms, observation with regular imaging may be recommended to monitor for changes.