By Jennifer Bradley, Staff Writer
Hereditary Neuropathy with Liability to Pressure Palsies
(HNPP) is the second major type of hereditary neuropathy.
It is also a slow progressing disease and common, but less
diagnosed than CMT. People with HNPP experience episodes of
numbness and weakness, brought on by fairly mild pressure or
trauma to a single nerve. Each episode of numbness may last for
several minutes, to several days or months. Two or three months
are the most common time periods for symptoms to last, but those
diagnosed have reported 6 to 12 months as well. The symptoms are
found to occur prevalently in the wrists, elbows and knees.
In 90 percent of people, HNPP causes carpal tunnel syndrome.
The symptoms and severity can vary greatly from individual to
individual; many people do not even know they have HNPP. The
numbness may be as mild as someone noticing an arm or leg
doesnít have quite the same feeling or, it could be as severe
that it feels like itís been numbed with Novocain. The same
scale goes for weakness, varying from slight to unable to move
an arm or leg.
Those living with HNPP, as with CMT, do not have a lessened
A third type of hereditary neuropathy is familial dysautonomia,
or Riley-Day syndrome. Itís prevalent in Jews of European
descent, also affecting both autonomic and sensory nerves.
In Riley-Day patients, symptoms will be noticeable in a
personís infancy. A baby may have difficulty feeding because of
decreased muscle tone. The child also will have problems
producing tears, and less-than-normal pain and temperature
A childís sense of taste is altered with Riley-Day syndrome.
In addition to a young child holding his or her breath, they
also struggle with blood pressure. This leads to dizziness and
fainting. Learning disabilities are common as well.
Unlike other forms of hereditary neuropathy, loved ones with
Riley-Day have a greatly reduced life expectancy.
How do you know?
If a loved one is suspected of having a hereditary
neuropathy, theyíll undergo an extensive neurological exam and
workup. This will include the following:
- Complete health history
Itís important a neurologist learns when the symptoms
started, their severity, duration, location, what relieves
- Neurological evaluation
This is a physical examination of reflexes, strength and
ability to feel sensations, in addition to evaluation of
autonomic nervous system.