Intramedullary Lesion
An intramedullary lesion is an abnormality located within the substance of the spinal cord itself. These lesions may represent inflammation, demyelinating disease, tumors, infection, vascular abnormalities, or fluid-filled cystic conditions. Because the spinal cord carries signals between the brain and the rest of the body, intramedullary lesions can produce a wide range of neurological symptoms depending on their size, location, and underlying cause. MRI of the spine is the primary imaging test used to evaluate these abnormalities and plays a critical role in narrowing the diagnosis.
What is it?
The term “intramedullary” refers to a process occurring within the spinal cord itself, rather than around it. An intramedullary lesion is therefore any abnormality identified inside the spinal cord on imaging.
These lesions may appear as areas of abnormal signal, swelling, cystic change, enhancement after contrast administration, or focal masses within the cord.
Intramedullary lesions can arise from many different conditions.
Inflammatory and demyelinating diseases are among the more common causes in adults and include multiple sclerosis, neuromyelitis optica spectrum disorder, and transverse myelitis.
Tumors arising within the spinal cord include ependymomas, astrocytomas, and hemangioblastomas.
Vascular causes include spinal cord infarction (spinal cord stroke), cavernous malformations, and arteriovenous malformations.
Other possible causes include infections, vitamin B12 deficiency, autoimmune disease, radiation injury, trauma, and syringomyelia, a condition in which a fluid-filled cavity develops within the cord.
Symptoms vary depending on which part of the spinal cord is affected and how extensive the lesion is.
Common symptoms include numbness, tingling, weakness, sensory loss, gait or balance problems, and neck or back pain.
Some lesions affect specific spinal cord pathways and may produce characteristic neurological patterns, such as predominantly sensory changes, motor weakness, or asymmetric findings.
When lower spinal cord regions or autonomic pathways are involved, bowel, bladder, or sexual dysfunction may occur.
MRI of the spine with contrast is the preferred imaging test for evaluating intramedullary lesions because it provides highly detailed views of the spinal cord, surrounding cerebrospinal fluid, nerve roots, and adjacent tissues.
Specific MRI characteristics—including lesion length, location within the cord, contrast enhancement pattern, cord swelling, associated cysts, hemorrhage, or accompanying brain lesions—often help narrow the differential diagnosis.
Brain MRI is frequently performed when demyelinating disease is suspected because many inflammatory conditions affect both the brain and spinal cord.
Additional evaluation may include blood testing, lumbar puncture with cerebrospinal fluid analysis, infectious or autoimmune studies, and, in select cases, biopsy.
Important to Know
Because “intramedullary lesion” describes a location rather than a specific diagnosis, identifying the underlying cause is the critical next step.
Treatment depends entirely on the specific condition responsible for the lesion.
Inflammatory and demyelinating disorders are commonly treated with corticosteroids, plasma exchange, immune-modulating medications, or long-term disease-modifying therapy coordinated by a neurologist.
Intramedullary tumors may require monitoring, surgery, radiation therapy, or additional oncologic treatment depending on tumor type and behavior.
Vascular abnormalities may require surgical or endovascular procedures, while infections are treated with targeted antimicrobial therapy.
Early diagnosis is especially important because some intramedullary lesions can cause permanent spinal cord injury if treatment is delayed.
Imaging findings are always interpreted together with neurological examination findings, clinical history, laboratory results, and cerebrospinal fluid analysis.
Red flag symptoms include rapidly progressing weakness, worsening numbness, gait or balance difficulty, bowel or bladder dysfunction, sudden severe neck or back pain, vision changes, or new neurological deficits. These symptoms require urgent medical evaluation because they may indicate significant spinal cord dysfunction or another serious neurological condition.