Multiple sclerosis (MS) is an immune mediated process in which an abnormal response of the body’s immune system is directed against the central nervous system (CNS). Within the CNS, the immune system causes inflammation that damages myelin sheath, the fatty substance that surrounds and insulates the nerve fibers as well and the specialized cells that make myelin.
Damage to the myelin or nerve fibers due to MS can alter or stop the message transmission within the CNS. If the CNS is damaged, it will result in an array of neurological symptoms depending on the type and severity of the MS. The name” Multiple Sclerosis” is derived from the scar tissue like appearance that develops around the damaged area due to the condition.
The exact cause of MS is unknown. There have been various researches that attribute multiple causes that might result in MS. Some of the researches have highlighted immunological, epidemiological, genetic and infectious agents as probable causative factors that result in MS.
Auto immune disorder is one of the major causative factors of MS. An abnormal immune response causes inflammation and damage in the CNS. There are 2 different types of immune cells which are involved in MS: T cells and B cells
“T cells” become activated in the lymph system and in MS, they enter the CNS through blood vessels. Once in the CNS, T cells release chemicals that cause inflammation and damage. This results in damage to myelin, nerve fibers and the cells that make myelin. T cells are also important to help activate B cells and call on other immune system cells to participate in the immune attack
The function of T regulatory cells, a type of T cell is to dampen or turn off inflammation. However, in multiple sclerosis, T regulatory cells do not function correctly and do not effectively turn off inflammation. On the contrary, cytotoxic or killer T cells directly attack and destroy cells bearing certain characteristics. B cells become activated with the help of T cells. Normally, B cells produce antibodies and stimulate other proteins, but in MS, they cause damage in CNS.
There are multiple environmental factors that contribute to the risk of developing MS. The predominant factors noted are:
There have been many reports that suggest bacterial or viral infections that can lead to MS. The Epstein-Barr Virus (EBV) have reported to be a significant factor that might have resulted in MS. Other factors such as measles, canine distemper, human herpes virus-6 and Chlamydia pneumonia have also been accounted for causing MS.
It is very important to understand that MS is not an inherited disease. Nevertheless, there is a greater genetic risk that may be inherited. The risk of developing MS is about 1 in 750-1000. But in identical twins, if one twin has MS the risk that the other twin will develop MS is about 1 in 4. The risk of developing MS is also increased when other first degree relative (parents, siblings and children) have MS, but far less than in identical twins. Various researchers have identified about 200 genes that contribute a small amount to the overall risk of developing MS.
Incidence and prevalence
According to a study conducted by National MS Society (US), nearly 1 million people are living with MS in the United States. A study found carried out in 2013 has stated that 4-5 % of all diagnosed MS cases are in children. The researches also highlight that more women have MS when compared to men. The National MS Society estimates MS is two to three times more common in women than men. One of the studies conducted in India have revealed the prevalence of MS to be approximately 1.33/100,000.
Symptoms of MS
- Dysesthesia (squeezing sensation around the torso)
- Gait disturbances
- Numbness or tingling sensation
- Spasticity (more common in lower limbs)
- Vision problems
- Vertigo and dizziness
- Bowel and Bladder problems
- Pain and itching sensation
- Cognitive changes
- Emotional disturbances
- Speech problems
- Breathing problems
SPEECH PROBLEMS SEEN IN INDIVIDUALS WITH MULTIPLE SCLEROSIS
MS lesions can cause damage to various parts of CNS. The significant impact to the frontal lobe can greatly impact speech and swallowing abilities of an individual. The speech and swallowing problems vary depending on the severity of the MS. The problems may range from mild difficulties to severe problems. The most common problems with speech are called as “Dysarthria”. Dysarthria is commonly associated with other symptoms that are caused by lesions in brainstem. These include, head shaking or incoordination.
There can be three type of dysarthria that can occur depending on the type and severity of MS lesions.
Spastic dysarthria: caused due to lesion in bilateral upper motor neuron, resulting in spasticity
Speech features include:
- A harsh, strained voice quality
- A slow rate of speech
- Reduced loudness or monotone speech
Ataxic dysarthria: caused due to lesion in cerebellum, resulting in incoordination.
Speech features include:
- A vocal tremor
- Dysrhythmic speech, rapid and alternating movements of the tongue, lips, and jaw
- Scanning speech, in which words come out very slowly or in strange rhythms with the syllables between them separated by long pauses, slurred speech, mumbling, or very slow speech
- Excess and variable loudness
Mixed dysarthria: Lesions in multiple areas of nervous system. The nerve damage may involve brain’s white matter, brainstem, cerebellum and spinal cord.
Speech features may include:
- Scanning speech : The most common speech difficulty noted among individuals with MS. The speech produced usually has disrupted “melody” or speech pattern is disrupted with abnormally long pauses between words or individual syllables of words.
- Slurring speech
- Imprecise consonant production
- Pitch breaks
- Low speech volume
Diagnosis and Intervention
A careful medical history, neurological examination and various tests including MRI, spinal fluid analysis and blood tests to rule out other conditions. It is very crucial to make quick diagnosis of MS as quickly and accurately as possible. The earlier the diagnosis, the greater the impact on positive intervention. The other diseases to be ruled out before arriving at the diagnosis of MS are as follows: infections of the CNS (Lyme disease, syphilis, progressive multifocal leukoencephalopathy, HIV), inflammatory disorders of the CNS (Vasculitis, systemic lupus erythematosus, sarcoidosis, Behcet’s disease), genetic disorders (leukodystrophies, hereditary cerebellar degeneration, mitochondrial disease), brain tumors (lymphoma, metastases), deficiencies (copper deficiency, Vitamin B12 deficiency).
The speech disorders seen in MS can be diagnosed by various subjective and objective measures. The various subsystems of speech such as respiration, phonation, resonance, articulatory and prosodic aspects can be assessed subjectively using various tests, rating scales, intelligibility and naturalness rating scales, etc. The objective assessment would include instrumental analysis involving Spirometer, CSL, Nasometer, Cinevideofluroscopy, Electropalatography, etc.
Speech therapy if initiated at an early stage, can be effective in dealing with communication problems that are caused due to MS. Speech therapist may work on strengthening on the speech muscles, increasing the lip and tongue movements, to control the rate the speech, prosodic aspects, speech intelligibility, etc.
Depending on the nature of speech problems, the SLP may:
- work through strategies to improve speech, such as talking more slowly or concentrating on speech
- help with exercises to improve the quality of voice. This might involve exercises with how to form words or with how to breathe when talking.
- help to find the right tools to support the communication. There is a range of possible technology, which includes amplifiers to make the voice louder and software to convert written information into speech.
- help the individual with MS and people they talk with most often to implement changes to compensate for difficulties. Suggestion may include making sure to implement face to face communication, reducing background noise and introducing the main topic before giving lots of detail.
- work with individual and the rest of multidisciplinary team to help the individual with MS manage the effects of fatigue on their communication.
Dysphagia is the condition in which an individual experiences difficulty in swallowing. This condition is often seen in individuals with MS. While this is more frequent to occur in advanced cases of the disease, it can occur at any stage. This may cause a person may cough after drinking liquids, or choke while eating certain foods, particularly those with crumbly textures.
Some of the common symptoms of dysphagia include:
- Coughing or choking when eating
- Feeling of food being lodged in the throat
- Unexplained recurrent lung infections
- Unexplained malnutrition or dehydration
When swallowing difficulties are present, food or liquids that we eat may be inhaled into the trachea (windpipe) instead of going down the esophagus and into the stomach. Once in the lungs, the inhaled food or liquids can cause pneumonia or abscesses. Because the food or drink isn’t reaching the stomach, a person may also be at risk for malnutrition or dehydration.
A speech language pathologist can usually treat swallowing problems. Treatment typically consists of changes in diet, positioning of the head, exercises, or stimulation designed to improve swallowing. In very severe cases that don’t respond to these measures, feeding tubes may be inserted directly into the stomach to provide the necessary fluids and nutrition.
Along with therapy, swallowing facilitatory measures can be implemented, such as:
- Sit upright at a 90° angle, tilting of head slightly forward
- Staying focused on the tasks of eating and drinking, less distraction, not talking when food is in mouth
- Eating slowly and small bites at a time
- Multiple swallows
- Concentrating on swallowing often
- Drinking plenty of fluids to stay hydrated
- Soft food consistency if chewing is laborious
Early diagnosis and early intervention are the precursors for good prognosis in MS
MVM College of Allied Health Sciences