Breathing and Respiratory Health

How CMT can affect your breathing

CMT is a neuromuscular disease, meaning it affects the nerves that control your muscles. Like other conditions in that family, it can weaken the muscles you need to expand your chest and draw a full breath, including the diaphragm, the dome-shaped muscle that sits beneath your lungs.

When those muscles weaken, doctors call the pattern restrictive lung disease. The lungs themselves are rarely damaged. The problem is muscle strength and control, and your breathing becomes shallower. Left untreated over time, lung capacity can slowly decrease.

This distinction matters, because it changes how the problem is found and how it is treated. How CMT affects you can also differ by CMT subtype and by your own individual factors.

Why symptoms often start at night

Breathing difficulties in CMT frequently show up first during sleep. When you lie flat, the weight of your abdomen presses up on the diaphragm, and a weakened diaphragm cannot push back as well.

Shallow nighttime breathing means you do not fully exhale carbon dioxide. Over time it can build up in the blood, a condition doctors call hypercapnia, or too much CO2 in the bloodstream.

Early signs vary from person to person, but they may include morning headaches, a common sign of overnight CO2 buildup, waking often or feeling unrefreshed after sleep, daytime sleepiness or fatigue, shortness of breath when lying flat, and less tolerance for exercise. If any of these sound familiar, bring them to your medical team.

Finding the right specialist

Not every lung specialist, or pulmonologist, has experience with neuromuscular disease, and the approach to CMT-related breathing differs from more common lung conditions. It is worth seeking out someone who knows this territory.

An HNF Center of Excellence can provide a referral or recommendation to a pulmonologist with neuromuscular experience. Knowing your genetic subtype through CMT Genie gives that specialist helpful context, too.

The right specialist can order the tests that matter most, including breathing tests done both seated and lying down (supine), because the supine test reveals diaphragm weakness a seated test alone may miss; fluoroscopy, an X-ray-based moving image, to watch the diaphragm move; and a sleep study, if needed, to assess your breathing overnight.

Non-invasive ventilation

If tests show significant breathing-muscle weakness, your doctor may recommend non-invasive ventilation, or NIV: breathing support delivered through a mask rather than a tube. It can be used at night only, during certain activities, or around the clock, depending on your needs.

For neuromuscular disease, the preferred form is BiPAP (bilevel positive airway pressure), sometimes called NPPV. These devices give more pressure as you breathe in to support weak muscles, and slightly less as you breathe out, so they actively assist each breath rather than just holding the airway open.

This is different from CPAP (continuous positive airway pressure), which keeps the airway from collapsing and helps with obstructive sleep apnea but does not assist weak breathing muscles. CPAP alone is generally not the right choice here.

One thing worth sharing with your pulmonologist: the key issue in CMT is inspiratory muscle weakness, or difficulty drawing a full breath in, not blockages in the airway. Standard sleep-study reports may not directly measure how deeply you breathe, so this distinction helps guide the right treatment.

A critical safety note on supplemental oxygen

People with restrictive lung disease from a neuromuscular cause need to be careful with supplemental oxygen. When extra oxygen raises the oxygen level in your blood, your brain can read it as a sign that you are breathing more deeply than you really are. It then eases off its signal to breathe, and carbon dioxide can build up quickly to dangerous levels.

If you or someone with CMT is given supplemental oxygen in a medical setting, make sure the care team understands that ventilatory support may be needed alongside it. This matters most in emergencies or after surgery, when staff may not be familiar with CMT.

Carrying a brief medical alert note or a letter from your neurologist that explains this is worth considering, so the point is not missed when it counts.

What the CMT community reports

Data from GRIN, HNF's global CMT research registry, shows that about 17% of participants report breathing issues related to their CMT. Rates vary by subtype and by individual factors.

If you have not yet joined, your participation helps researchers understand the full range of CMT symptoms, respiratory complications included. You can learn more and sign up through the GRIN Registry.

An honest note on treatment

There is currently no approved treatment that stops or reverses CMT. Non-invasive ventilation manages symptoms and protects your quality of life, but it does not repair the underlying nerve damage.

Research into CMT therapies is active and promising, and joining the GRIN Registry contributes directly to that work. For the full library of condition-specific guides, visit Patient Resources. And always work with your medical team when you have concerns about breathing; the guidance here is general, and your clinician knows your situation best.