Different areas of the central nervous system perform different functions, and MS symptoms can vary greatly depending on the site of the lesion (inflammation or scarring.) MS doesn't usually affect the nerve cells themselves but interferes with their transmission of electrical signals by damaging their insulating myelin coating. Symptoms are usually more pronounced in active MS – during acute inflammatory episodes or chronic progressive disease -- and may lessen or even vanish when the disease is in remission.
Much of the nervous system’s function involves the processing of sensations carried to it by nerves and tracts and the sending of signals to control muscles to cause movement, so most often – but NOT exclusively - MS affects sensory or motor function. However, MS can affect emotion, memory and other cognitive processes as well.
Physical symptoms of MS include (but are not limited to) trouble with sight or eye movements, instability in walking, clumsiness or weakness, changes in normal reflexes, difficulty with bowel or bladder function, and/or alterations of sensation. Cognitive symptoms can range from the generality of depression through such specific things as difficulty with word retrieval or short-term memory.
Visual Symptoms
A person with optic neuritis (inflammation of the optic nerve) or plaques on the optic nerve may have:
- haziness or a cloud in one eye
- trouble seeing colors vividly or reading small print
- a central area of blackness
- pain that increases as the subject moves the eye
A person with motor lesions affecting eye muscle control may have:
- double vision
- rhythmic, back and forth (or up and down) movement in one or both eyes, called nystagmus
- difficulty or slowness in tracking moving objects with either or both eyes
Motor Symptoms
Motor symptoms from MS lesions are extremely variable and can range from slight weakness or lack of coördination to total paralysis or loss of control over one or more muscle groups.
These symptoms may include:
- lack of control, power or fluidity in movements
- dulled or hyperactive skeletal reflexes
- spasticity (resistance to movement or tightness in one or more muscle groups)
- painful spasms and muscle contractures (contracture is a scarred-in, permanent shortening of a muscle that can usually be prevented)
- the famous Babinski sign (scratching the bottom of the foot makes the big toe go up)
- bladder or bowel urgency (needing to get to the bathroom fast or needing to go frequently)
- urinary or bowel hesitancy or retention (trouble either allowing voiding or fully emptying the bladder or bowel).
- signals crossing so both the bladder and its sphincter tighten at once
Sensory Symptoms
Like motor symptoms, sensory symptoms (and where they are felt) can vary widely, depending on the location and size of the lesions that produce them.
They can include:
- the "MS hug" - a band-like and sometimes painful tightening sensation around the torso or chest
- L’Hermitte’s sign – an ‘electric shock’ sensation that travels down the trunk or into an arm or leg when the head bends forward
- unusual or persistent burning or tingling sensations, pain or numbness
- dizziness or vertigo
- facial pain
- difficulty telling the difference among heat, cold and pain
Cognitive Symptoms
Cognitive (mental and emotional) symptoms due to MS can be very difficult to accurately diagnose. While they have come to be widely recognized in the literature, many specialists have trouble dealing with them. This can be because of the very difficulty in tracing a symptom’s origin to MS, but is still due sometimes to a doctor’s own reluctance to accept MS itself as a possible cause of many of these symptoms. Any of these symptoms may be caused by something ‘general’ like depression (which itself can be either a symptom of MS *or* a fairly normal reaction to its diagnosis or progression,) or by any of several other disorders both organic and psychological.
These symptoms include:
- excessive drowsiness
- low levels of initiative or motivation
- emotional "numbness" (emotions are weak or they "trail off")
- poor mental acuity ("fuzzy thinking")
- poor selective attention (difficulty choosing what to think about, look at, listen to)
- poor concentration
- distractibility
- tangentiality (mind wandering, difficulty staying on task)
- impulsivity or disinhibition (difficulty controlling or restraining impulses)
- perseveration ("getting stuck" on a thought or a behavior)
- problems processing intense, complex, or fast moving sensory input
- problems with recognition (for instance, you can see it, but it doesn't register)
- processing delays (afterimages, trails, ringing in your ears)
- unstable perceptions (surroundings seeming to move when you do)
- spatial disorientation (e.g., getting lost on the way to a familiar place)
- problems with balance, body awareness, or coordination
- poor reflective awareness (not being aware, or conscious, of yourself)
- indecisiveness
- problems with planning or organization
- problems with abstract thinking, judgment, or reasoning
- tunnel vision (difficulty seeing things from different points of view, or considering different ways to do things)
- problems understanding or comprehending what you read or hear
- problems with memory
This is by no means an exhaustive list of symptoms, and not everyone with MS will have all of these signs. Different people will be affected in different ways, which all depend on the anatomy of their own disease process.
