Intramedullary Spinal Cord Tumor

Overview

An intramedullary tumor is a neoplasm that arises within the substance of the spinal cord itself, not in the surrounding membranes or bony spine, but inside the cord's own neural tissue. Because the spinal cord is densely packed with the fiber tracts that carry movement and sensation signals between the brain and the rest of the body, a tumor growing within it expands the cord from inside, displacing and infiltrating those pathways. In many cases an associated fluid-filled cavity called a syrinx forms and extends the zone of injury well beyond the tumor's actual margins.

These tumors are uncommon overall. Among spinal cord tumors, intradural extramedullary lesions, those inside the protective dural covering but outside the cord itself, are more frequent. Intramedullary tumors can occur at any age, but the relative mix of types shifts over the lifespan: ependymomas predominate in adults and are particularly common in the cervical and cervicothoracic cord, while low-grade astrocytomas are proportionally more common in children and young adults. Hemangioblastomas, often linked to von Hippel-Lindau disease, make up a smaller fraction. Intramedullary metastases, cancer that has spread from elsewhere in the body to the cord parenchyma, are rare but increasingly recognized in patients with advanced systemic disease, most often from lung or breast primaries.

What causes it

The two most common primary intramedullary tumors in adults arise from the cord's own cells. Ependymomas develop from the ependymal lining of the central canal and tend to be relatively well circumscribed, which can allow for a more complete surgical removal. Astrocytomas arise from glial support cells and tend to be more infiltrative, often without a clear boundary between tumor and normal cord. Hemangioblastomas are vascular tumors strongly associated with von Hippel-Lindau disease, a hereditary condition; their discovery should prompt evaluation for related lesions elsewhere in the nervous system and consideration of genetic assessment. Neurofibromatosis type 2 is a recognized risk factor for ependymomas.

Intramedullary metastases occur when cancer cells from a systemic tumor, most often lung or breast cancer, reach the cord through the bloodstream. Their presence in a patient with known cancer warrants immediate concern. Regardless of type, the neurologic deficit reflects a combination of direct mechanical distortion of neural tissue, peritumoral edema, and the amplifying effect of any associated syrinx.

Symptoms and warning signs

The clinical course is typically insidious and slowly progressive over months, although metastatic and higher-grade lesions can evolve more rapidly. The earliest complaints are often poorly localized pain in the back or neck, sometimes worse at night or when lying down. As the tumor grows, sensory disturbances follow: patients may notice numbness, tingling, or a burning quality (dysesthesia), or a distinctive cape-like band of reduced pain and temperature sensation in the upper trunk and arms when the central cord is involved. Progressive weakness in the legs or arms, muscle stiffness (spasticity), an unsteady gait, and, as the lesion enlarges, bladder and bowel dysfunction emerge in sequence. On examination, findings often reflect a combination of upper motor neuron signs below the level of the tumor (spasticity, overactive reflexes) and segmental lower motor neuron findings at the level itself.

Certain features are urgent warning signs that require prompt evaluation. Progressive motor weakness, especially weakness that is worsening over days to weeks, should not be observed and waited on. Any new sign of spinal cord dysfunction (myelopathy) in a patient with a history of cancer should raise immediate concern for malignant cord involvement and prompt expedited imaging and oncologic assessment. New or worsening bladder or bowel dysfunction similarly signals significant cord compromise and requires urgent attention, because timely intervention may prevent irreversible loss of function.

How it's diagnosed

MRI of the entire neuraxis with and without gadolinium contrast is the study of choice. It shows the characteristic fusiform (spindle-shaped) expansion of the cord, signal change on T2-weighted sequences, the pattern and intensity of contrast enhancement, and associated features such as cysts, a syrinx, old hemorrhage (the hemosiderin "cap sign" characteristic of ependymomas), or enlarged vessels suggesting a hemangioblastoma. Central, relatively symmetric enhancement favors an ependymoma, while eccentric or patchy enhancement is more typical of an astrocytoma.

CT and plain radiographs offer limited information about the tumor itself but can characterize bony anatomy and detect calcification or skeletal metastatic disease. When metastasis is suspected, imaging is correlated with the patient's oncologic history and staging workup, and cerebrospinal fluid analysis may be considered for tumors with a tendency toward leptomeningeal spread. Crucially, a tissue diagnosis, obtained at surgery, is the definitive step that establishes the exact tumor type and grade. Imaging findings must always be interpreted alongside the full clinical history and neurologic examination.

Treatment options

Management is individualized based on the tumor type, the patient's neurologic status, and overall health and prognosis. There is no single treatment pathway; a multidisciplinary discussion between the neurosurgeon, neuro-oncologist, and radiation oncologist is standard for most cases.

Adjuvant radiotherapy, radiation delivered after surgery, is used for subtotally resected, recurrent, or higher-grade tumors rather than as the primary treatment for most intramedullary lesions. Chemotherapy has a more limited, tumor-specific role and is not universally indicated across all subtypes.

For intramedullary metastases, treatment is usually palliative and multidisciplinary, emphasizing radiotherapy, corticosteroids to reduce peritumoral edema, and systemic oncologic therapy. Surgery may be considered selectively for tissue diagnosis or when rapidly progressive cord compression demands decompression.

Corticosteroids are frequently used in the acute setting to reduce edema and temporarily stabilize neurologic function while the diagnosis is established and a treatment plan is formed.

When surgery is considered

Surgery is the primary treatment for most primary intramedullary tumors when the patient's neurologic status and overall health allow it. The approach is posterior, through the back of the spine, and intraoperative neurophysiologic monitoring (continuous measurement of spinal cord signals during the operation) is a standard safety measure that helps guide the surgeon in preserving functional neural tissue.

For ependymomas and hemangioblastomas, which tend to be more well-defined, microsurgical resection offers the best opportunity for a gross total removal and durable neurologic stabilization or improvement. Surgery is generally recommended when a meaningful resection is feasible or when a progressive neurologic deficit requires decompression and a tissue diagnosis.

For infiltrative astrocytomas, the absence of a clear surgical plane between tumor and cord increases the risk of worsening deficit with aggressive removal. The surgical goal is typically a biopsy and judicious debulking to reduce mass effect and obtain a histologic diagnosis rather than an attempt at radical resection.

Across all subtypes, early recognition and referral, before severe deficits have developed, is one of the most important factors influencing functional outcome. Once significant cord function is lost, it may not recover even after the tumor is treated, which is why acting promptly on red flag symptoms matters.