CMT and fatigue: Why are we so tired? by Dr. Greg REPOST

[Guest guest]

CMT and fatigue: Why are we so tired?

http://lindacrabtree.com/cmtnews/fatigue/fatiguepage1.html

by Greg , M.D., Medical Director, Providence Rehabilitation

Hospital, Chehalis, WA, U.S.A.

Skeletal muscle weakness and loss of sensation are the ultimate

causes of the majority of clinical problems associated with CMT.

Fatigue in CMT is likely multifactorial and due, in part, to impaired

muscular activation. Other contributing factors include generalized

deconditioning from immobility and imposed sedentary lifestyle.

Besides diffuse muscle weakness, atrophy and fatigue, there is also a

reduced functional exercise capacity. Although these are common

problems in CMT they have not been well quantified. We did one

limited study about 10 years ago. We took 12 adult subjects with CMT

type I, and 10 subjects without CMT and measured pulmonary

(breathing) function, including tidal volume (VT), respiratory rate

(RR), minute ventilation (Ve), oxygen uptake (VO2), oxygen saturation

(SaO2), carbon dioxide production (VCO2), inspiratory flow (VT/Vi),

and heart rate (HR).

We then administered the Lee Fatigue Scale, the Lareau Functional

Status Scale, Borg Perceived Exertion Scale, and the Profile of Mood

States (POMS) measured before and after unsupported arm exercise

(UAE). Results showed fatigue was moderate to severe and functional

state was reduced compared to subjects without CMT. This was true

both before and after exercise, with significant increases in fatigue

reported post exercise. Our findings indicated that people with CMT

have elevated fatigue intensity and distress before and after

exercise. Functional state is also much lower in CMT.

Pain, and occasionally, depression, can also contribute to fatigue or

the sense thereof. Some reactive clinical depression is expected in

CMT if there is significant loss of function. Good family, social,

and religious support systems are helpful in this regard. Anti-

depressant medicine should be considered since it may provide

assistance with energy levels, mood-elevation, appetite stimulation

and sleep.

Aerobic exercise not only improves physical functioning but is

beneficial in fighting depression and improving pain tolerance, two

things that are critical in CMT. There have been few well-controlled

studies looking at exercise induced strength gains in CMT.

My colleague Dr. Dave Kilmer had CMT subjects do a 12 week moderate

resistance (30% of maximum isometric force) exercise program which

resulted in strength gains ranging from 4% to 20% without any notable

deleterious effects. However, in the same population, a 12 week high

resistance (training at the maximum weight a subject could lift 12

times) exercise program showed no further added beneficial effect

compared to the moderate resistance program and there was evidence of

overwork weakness in some of the subjects.

The risk for overwork weakness is great in CMT and exercise should be

prescribed cautiously and with a common sense approach. People with

CMT should be advised not to exercise to exhaustion, which can

produce more muscle damage and dysfunction. The warning signs of

overwork weakness include feeling weaker rather than stronger within

30 minutes post exercise or excessive muscle soreness 24-48 hours

following exercise. Other warning signs include severe muscle

cramping, heaviness in the extremities, and prolonged shortness of

breath.

Nonetheless, gentle, low impact aerobic exercise like walking,

swimming, and stationary bicycling will improve cardiovascular

performance and increase muscle efficiency, and thus help fight

fatigue.

Up until a few years ago, pain was not frequently characterized as a

major component of CMT. However a study sponsored, and funded in part

by CMT International, showed that the majority of people with CMT do

experience significant pain. The pain is due largely to damaged

nerves causing " neuropathic pain " (stinging, burning). However,

immobility, which can cause adhesive capsulitis, mechanical back

pain, and pressure areas on the skin also likely contribute. Chronic

pain can be immensely fatiguing and it would be helpful for those

with chronic pain to have it treated aggressively.

Pharmacological management of pain in CMT includes the use of non-

steroidal anti-inflammatory (NSAID) medication, particularly if there

is evidence of active inflammatory process like tenosynovitis or

arthritis. Regular dosing of acetaminophen (1000 mg every 6 hours)

may be used along with an NSAID or alone if NSAIDs are not tolerated.

Anti-depressants and anti-convulsants (neurontin) are particularly

helpful for neuropathic pain.

Narcotic medicine should also be considered for refractory pain. If

narcotics have helped, then taking the total dose of immediate

release (short acting) narcotic required to alleviate pain and giving

half of that every 12 hours in a controlled-release preparation such

as OxyContin may be helpful.

Proper equipment is crucial to maintaining energy. Braces (ankle-foot

orthoses, etc) should fit well and be in good repair. Wheelchairs

should have adequate lumbar support and good cushioning (gel-foam).

The chair should be properly fitted (generally done by occupational

therapist) to avoid pressure ulcers and inadequate support for the

spine. Wheeled walkers (Gran Tour in particular) or quad (four point)

canes may also help, depending on the pattern of weakness.

Some may benefit from Canadian style forearm crutches to steady them.

Other useful equipment includes hand-held showers, bathtub benches,

to shower and toilet grab bars (Versa frame), raised toilet seat,

automatic toileting device, hospital bed, commode chair, ADL aids

(sock aid, grabbers, etc), and wheelchair ramps. An occupational

therapist will help define which, if any, of these devices will be

useful to the patient. They can also go over pacing and energy

conservation techniques.

Respiratory failure occasionally will develop in CMT, due to weakness

of the diaphragm, chest wall, and abdominal musculature. This is

usually manifested by hypoventilation, which leads to elevated carbon

dioxide levels in the blood. This will cause fatigue. A thorough

review of systems by your physician will help define any problems.

Patients that are hypoventilating will often complain of a morning

headache, restlessness or nightmares, and poor quality sleep. This

may cause daytime somnolence and fatigue.

Dr. Bach has shown significant success with the use of

intermittent positive pressure ventilation by mouth (IPPV). This type

of ventilation does not require a tracheostomy and may markedly

improve quality of life. IPPV can be done easily in the home and

should be considered in people with CMT and respiratory failure or

sleep apnea. Patients may benefit initially from using IPPV mainly at

night. (See also under the heading Breathing)