Multiple Sclerosis (MS) is a complex condition that affects the central nervous system (CNS), including the brain, spinal cord, and optic nerves. This autoimmune disease causes the immune system to mistakenly attack myelin, the protective covering of nerve fibers. This damage results in areas of inflammation and scarring, often visualized as lesions on imaging scans. People often wonder if they can feel the physical presence of these lesions, which represent the underlying damage of the disease.
Understanding the Nature of MS Lesions
An MS lesion is an area of inflammation followed by subsequent scarring, or sclerosis, within the CNS. Immune cells target and destroy the myelin sheath, a process known as demyelination. Myelin acts like insulation around an electrical wire, ensuring signals travel quickly and efficiently.
The formation of scar tissue in place of healthy myelin gives the disease its name: multiple areas of sclerosis. These lesions vary widely in size and shape and are scattered throughout the brain, spinal cord, and optic nerves. The specific location and extent of this damage determines the resulting symptoms a person experiences.
The Direct Answer: Feeling the Lesion’s Effect
A person does not directly “feel” the lesion itself, meaning they cannot sense the physical scar tissue or inflammation. Instead, they experience the consequence of the lesion: the disruption of electrical signals traveling through the nervous system. Myelin damage interferes with nerve cell function, causing electrical messages to slow down, become scrambled, or be completely blocked.
When nerve fibers lose their protective coating, they can become hyperexcitable, firing signals too frequently or inappropriately. This miscommunication generates false signals of touch, pain, or temperature that originate in the brain or spinal cord. Because the signal disruption occurs within the CNS, the resulting sensation is a neurological symptom rather than a feeling of physical damage at the lesion site.
Common Sensory Disturbances Caused by Lesions
The disruption of nerve signals frequently manifests as a range of abnormal sensory experiences. One common experience is paresthesia, which describes unusual sensations such as tingling, “pins and needles,” or itching on the skin. These sensations are often fleeting and result from damaged nerve fibers misfiring.
Another frequent symptom is dysesthesia, which involves painful or unpleasant sensations like burning, aching, or a tight, constricting feeling. This is sometimes described as an “MS hug” and is considered a type of neuropathic pain caused by nerve damage.
A more specific disturbance is Lhermitte’s sign, a brief, electric shock-like sensation that travels down the spine and into the limbs. This sensation is often triggered by bending the neck forward. It is thought to involve demyelination in the cervical spinal cord.
How Lesion Location Determines the Sensation
The specific type of sensation experienced is determined entirely by which area of the central nervous system the lesion has damaged. Lesions in the optic nerve, which transmits visual information, can cause vision issues, such as blurred vision or pain upon eye movement. This occurs because the signal pathway for sight has been compromised.
Damage to sensory pathways within the spinal cord can lead to numbness, tingling, or pain below the level of the lesion. For instance, a lesion in the upper spinal cord might cause abnormal sensations starting in the chest and extending downward. Lesions in the cerebellum, the part of the brain responsible for coordination, can cause a person to perceive a lack of stability or control over their movements. This altered sense of movement, or ataxia, is tied directly to the anatomical location of the damage.