[APRAX] mitochondtrial disorders and speech--possible connections for some

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Vol. 17 •Issue 26

• Page 10

Mitochondrial Disease

What clinicians can do to help patients with this progressive metabolic disorder

By R. Shedd, MS, CCC-SLP

Speech-language pathologists and audiologists see children with

mitochondrial disease on their caseloads. Many of these children have

concurrent autistic characteristics, apraxia of speech, low verbal

skills, dysarthria, atypical cerebral palsy, deafness, auditory

processing disorders and swallowing deficits. A number of children with

mitochondrial deficits are nonverbal, and many don't eat.

Mitochondrial disease is a group of progressive metabolic

disorders that attacks the body at the very source of energy and life:

the mitochondria. Within these subcellular organelles a natural process

occurs called cellular respiration. As our body takes in food, cellular

respiration, also known as the Krebscycle, turns it into an energy

source that the body can use.

Mitochondria produce 90 percent of the life-sustaining energy

that we require in order to function appropriately and live. When they

don't work properly, less energy is created in the cell. This can

result in cell injury and death. Progression within tissues and organ

systems can result in biological death of the body. Mitochondrial

diseases starve the body of necessary energy to function properly. For the

people who are affected by this disease, energy for

daily activities may become severely compromised. They become fatigued

easily and may ache as a result of physical activity. Life becomes a

blur of doctor's appointments, hospital stays and pain. The disease can

strike children and adults alike, depending on how progressive the

disorder is. According to the United Mitochondrial Disease Foundation,

mitochondrial dysfunction can cause a wide range of deficits, including

developmental delay or regression (including dementia), seizures,

myoclonus, movement disorders, migraine, stroke, neuropathy, heart

deficits, hearing loss and deafness, vision loss and blindness and

diabetes.

Doctors should investigate a potential mitochondrial disorder

when three or more systems of the body are affected. Current estimates

indicate that one in every 2,000 to 4,000 babies will be born with a

mitochondrial deficit or will develop it by age 5.1

Although research of this metabolic disease provides hope for a

future cure, the current picture is bleak. Prescribed vitamin therapies

may help patients with the disorder by increasing mitochondrial

function. Affected individuals usually need to undergo physical,

occupational and speech therapies. Although they experience

deterioration and regression in terms of skills, abilities and

lifespan, no one can predict the rapidity. Dysphagia may be an early indicator

that a neuromuscular disease is present, according to the Muscular Dystrophy

Association.2

Failure to thrive in infants should be monitored carefully for other

concomitant health issues that may point the cause of failure to

mitochondrial myopathies. Many of these remain petite and have

difficulty gaining weight.

However, some mitochondrial diseases may cause excessive weight

issues in patients. These people present with variations called fatty

oxidation diseases and cannot metabolize fats in their body.

Mitochondrial disease may be the underlying reason for the child who

just seems " odd. " Although speech-language pathologists cannot diagnose

mitochondrial disease, we can look at our patients objectively and

recognize the multisystemic impairments that may indicate the disorder.

Neurologists and geneticists complete the definitive diagnostic

assessment by first evaluating basic metabolic panels.

Testing proceeds with urine analysis, spinal taps, nerve

conduction studies, skin biopsies, and magnetic resonance imagining

(MRI) studies, particularly of the brain. The final, most invasive but

conclusive test is a muscle biopsy. Not all potential assessment

procedures are used with each patient. Ongoing procedures may last

several weeks or months before results yield answers. Speech-language

pathologists commonly see patients with

globally weak muscles who have the same weakness within the oral

musculature. They present with dysarthria, dysphagia and hypotonia of

the oral musculature.

Therapy works to strengthen these weaknesses. However, it is a

fine balance for a person with a mitochondrial disease to work the

muscles to gain strength but to not overwork the muscles so thatfatigue

increases.

The cellular respiration process of turning food into a viable

energy source uses a component called lactonase dyhydrogenase, which

commonly is associated with lactic acid. Most people experience lactic

acid build-up in their body after they work their bodies in an

unusually hard or novel way.

People with mitochondrial disease sometimes do not use the

lactonase dyhydrogenase in their bodies properly and therefore

experience lactic acidosis, which causes sore muscles and fatigue.

Simple exercises such as walking to the mailbox may be too much. They

may experience a feeling of " crashing, " where they have no energy,

excess soreness and pain, or unusual variations in core body functions.

Over-exertion is also a risk within the oral musculature, potentially

leading to exhaustion, soreness, fatigue and muscle damage. Although

speech-language pathologists know that any effective

therapy must contain constant reassessment, it is even more important

with patients who have mitochondrial disease. Muscle fatigue may cause

constant variations in skills and strengths on any given day.

Another cause of concern is the risk of seizures, developmental

delay and stroke that may co-exist with the disease, stripping

speech-language function at any time and without warning. Therapists

should constantly re-evaluate current skills for speech-language

production, swallowing and hearing in every speech session.

Each day must be considered different than the day before. The

patient may be able to accomplish the same tasks as yesterday, more

than before, or fewer due to regression and the loss of learned skills.

Mitochondrial myopathies have been related directly to hearing

loss and deafness. Aminoglycoside antibiotics—such as amikacin,

neomycin and streptomycin—have been known to cause ototoxicity and

deafness in certain patients for more than 40 years.

" A mitochondrial mutation occurs in [all those] with a trait

for hypersensitivity to aminoglycosides, " according to the American

Journal of Audiology.3 Thus, a mitochondrial deviation from these antibiotics is

related directly to deafness.

One of the hardest things for parents and professionals dealing

with mitochondrial disease in children is to realize and accept the

illness. Because of the inconsistent symptoms and energy levels, a

professional may see an exuberant and energetic child, while the

parents deal with the aftermath of a fatigued child who can no longer

move without pain. An affected child may appear " petite " to a

professional, but the parents see a child who gags, refuses food, has

trouble eating, or is unable to gain weight despite great intake. A

professional may see a child who is functioning fine, while the parents

know the child may be glum tomorrow.

Children and adults presenting with mitochondrial disease

typically look normal in outward appearance. Being with the child more

regularly than physicians, speech-language pathologists are more likely

to see and understand the aftermath that the parents witness. We are in

the position to be an advocate for these patients.

Individuals with mitochondrial disease are on our caseloads. We

may see those who are mildly affected for articulation disorders or

mild language difficulties and those with more severe involvement for

swallowing difficulties, auditory processing difficulties, apraxia,

dysarthria, hearing impairment, dystonia and developmental delays. We

fit them with augmentative and alternative communication (AAC) devices

because they are unable to speak and have such poor muscle strength

that sign language is difficult.

Some of these patients may not live to see the end of this

year. Some have a lifetime ahead of them. The question is " What will we

do to help them all? "

References

1. United Mitochondrial Disease Foundation. (2000). When to suspect

mitochondrial dysfunction. Accessed online at www.umdf.org.

2. Ivory, P. (1999). Muscular Dystrophy Association. MDA publications. Hard to

swallow. Quest, 6 (4). Accessed online at www.mda.org.

3. Hutchin, T.P., Cortopassi, G.A. (1995). Mitochondria and risk for deafness.

American Journal of Audiology, 4: 12-14.

For More Information

Muscular Dystrophy Association, online: www.mda.org

United Mitochondrial Disease Foundation, online: www.umdf.org

Shedd is on staff at the Vicksburg Warren School District in Vicksburg,

MS. She can be contacted at (601) 529-1861 or Shedd2003@....

Possible Symptoms

Poor growth

Loss of muscle coordination

Muscle weakness

Visual and/or hearing problems

Developmental delays, learning disabilities

Mental retardation

Heart, liver or kidney disease

Gastrointestinal disorders

Respiratory disorders

Diabetes

Increased risk of infection

Neurological problems, seizures

Thyroid dysfunction

Dementia