Dumbbell = having the shape of a dumbbell (narrower in the middle than on each end)
Tumor = an abnormal growth
A dumbbell tumor is any tumor that is constricted in the middle, giving it the shape of an hourglass or dumbbell.
In the spine, dumbbell tumors consist of one part of the tumor inside the spinal canal and another outside the spinal canal. The narrow section connecting these two parts passes through an opening in the spinal column called the neural foramen.
Many kinds of tumors can be dumbbell-shaped. The most common ones are the nerve sheath tumors, schwannomas and neurofibromas. These tumors grow in the insulating membranes, or sheaths, around the spinal nerves. The nerves pass through the neural foramen, and the tumors grow along the same course. Meningiomas, sarcomas, and lymphomas can also have a dumbbell shape.
Most dumbbell tumors are benign, but not all. Treatment depends on the type of tumor. Nearly all dumbbell tumors can be safely removed with surgery.
When one section of a growing dumbbell tumor compresses the spinal cord or a nerve, the compression can cause spinal cord or nerve damage.
Symptoms can include pain, numbness, weakness, “pins and needles,” clumsiness, difficulty walking, or incontinence. Exact symptoms depend on the size and location of the tumor.
Causes and Risk Factors
The causes and risk factors depend on the type of tumor.
Nerve sheath tumors and meningiomas are sometimes caused by a set of inherited conditions known as neurofibromatoses. Sometimes these tumors occur for no known reason; these are called sporadic cases.
Tests and Diagnosis
Dumbbell-shaped tumors are commonly diagnosed using imaging studies like CT (computed tomography–a CAT scan) or MR (magnetic resonance). CT uses a combination of X-rays and computer technology to produce detailed images of bones and soft tissues; MR scans use magnets, radio waves, and computer technology to produce images of organs like the brain and spinal cord.
These studies give the best information about soft tissue tumors.
Microsurgery is the treatment of choice for nearly all dumbbell tumors.
Neurosurgeons perform microsurgery using an operating microscope and fine surgical instruments. Depending on the size and location of the tumor, the neurosurgeon will choose from a variety of microsurgical techniques and approaches. Most dumbbell tumors can be safely removed using standard microsurgical techniques.
The surgeon may need to remove some bone to access the tumor, in a procedure called a laminectomy. To maintain spinal stability, a spinal fusion may then need to be performed. Watch this video of this procedure.
Stereotactic radiosurgery may be used to treat any remaining portion of the tumor that cannot be safely removed at surgery.