Transverse Myelitis, Part 2
In my previous post I reviewed the basic anatomy of the spinal cord, one of the main site of damage in MS. As with lesions in the brain, lesions in MS tend to affect the white matter and involvement of the gray matter suggests an illness other than MS. The MRIs below show the spinal cord from different angles affected by plaques in MS.
Inflammation of the spinal cord is termed myelitis. In MS, symptoms stemming from the spinal cord typically present as an ascending numbness that often starts in one limb and then spreads to include a much wider area. It is very common for patients to develop numbness in a foot for example, that creeps up their leg. Over the course of a day or two patients may develop numbness from their waist or chest downwards. Patients may feel a banding sensation as if they have a tight belt around them. This is sometimes referred to as the “MS Hug” and this feeling can remain for a long time after the acute inflammation has resolved. Lesions higher up in the cervical spine may cause similar sensory disturbances in the arms. When MS patients feel tingling and numbness in their extremities, it is usually due to lesion affecting the sensory pathways of the spinal cord.
Lesions in the uppermost part of the cervical spine may produce what is called Lhermitte’s sign. This refers to an electrical shock sensation in the limbs and body brought on by flexion of the neck. Although Lhermitte’s sign is common in MS, it can be due to other illnesses of the cervical spine. Below is the MRI of a patient who presented with this symptom.
Lesions to the corticopsinal tract produce weakness in the limbs as well as trouble with balance and walking. And while a single lesion is unlikely to cause the acute onset of bowel and bladder symptoms, the accumulation of lesions in the spinal cord results in these symptoms over time.
As with optic neuritis, transverse myelitis is often a frequent presenting symptom of MS. However, transverse myelitis can also be a post-infectious process that is not likely to lead to MS. As with optic neuritis, the presence or absence of additional brain lesions and the presence of absence of oligoclonal bands in the spinal fluid can help doctors and patients alike determine whether treatment for MS is required. Ultimately, simply waiting to see if there is a second clinical event or changes on the MRI are the only way to know for sure if a patient is going to develop MS or not.