and Prader Willi Syndrome
James Loker, MD, Laurence Rosenfield, MD
Issues Affecting Prader Willi
Syndrome and Anesthesia
In individuals with Prader-Willi Syndrome there are health issues that can alter the course of anesthesia.
Obese individuals are more prone to obstructive apnea, pulmonary
compromise, and diabetes. Each of these should be taken into account when
preparing for anesthesia. The individual may have altered blood oxygen or
blood carbon dioxide levels that will change their response to medications
including oxygen. Pulmonary hypertension, right-heart failure, and edema
may necessitate evaluation by a cardiologist or pulmonologist prior to
surgery. An ECG to detect right ventricular hypertrophy may be beneficial
to assess pulmonary hypertension. Frequently obese individuals with PWS
may have significant body edema (extra fluid) that is not fully
appreciated due to obesity. This should be carefully evaluated, and if
necessary, diuretics used before and after the anesthesia. Airway
management can be a particular problem when conscious sedation is used.
Threshold- Individuals with
PWS may not respond to pain in the same manner as others. While this may
be helpful in post-operative management, it may also mask underlying
problems. Pain is the body's way of alerting us to problems. After
surgery, pain that is out of proportion to the procedure may alert the
physician that something else is wrong. Other possible signs of underlying
problems should be monitored.
Instability- The hypothalamus
regulates the body's temperature. Because of a disorder in the
hypothalamus, individuals with PWS may be either hypo- or hyperthermic.
The parent or caregiver can be helpful in letting the anesthesiologist
know what the individual's usual temperature is. Although there is no
indication of a predisposition to malignant hyperthermia in PWS,
depolarizing muscle relaxants (i.e., succinylcholine) should be avoided
unless absolutely necessary.
A common problem in PWS is unusually thick saliva. This can complicate
airway management, especially in cases of conscious sedation or during
extubation (when a breathing tube is removed). Thick saliva also
predisposes an individual to dental caries (cavities) and loose teeth.
Oral hygiene should be evaluated prior to anesthesia.
Behaviors- It is vitally
important that any individual undergoing general anesthesia or conscious
sedation have an empty stomach. This reduces the risk of aspiration of the
stomach contents into the lungs. Individuals with PWS generally have an
excessive appetite and may not tell the truth if they have eaten just
Any individual with
PWS should be assumed to have food in the stomach unless it is verified by
the caregiver that they have not eaten. A tube may need to be placed in
the stomach to assure no food is present prior to attempting to place the
breathing tube. Some individuals with PWS may ruminate (regurgitate some
of their food) and are at higher risk of aspiration.
The majority of infants with PWS are significantly hypotonic. This usually
improves by 2-4 years of age. The majority, however, continue to have
lower muscle tone than normal individuals. This may be a problem in the
ability to cough effectively and clear the airways after use of a
Habitual skin picking can be a significant problem in PWS. This can
complicate healing of IV sites and incisional wounds. Usually if these
remain well covered, they will be left alone. Depending on the
individual's cognitive impairment, restraints or thick gloves may be
needed to protect surgical wounds during healing.
Since PWS is a hypothalamic disorder, other hypothalamic functions are at
risk. Although the incidence of hypothyroidism in PWS is not known, low
levels of thyroid hormone could occur due to lack of thyroid stimulating
hormone or thyroid releasing factor, not necessarily due to problems of
the thyroid gland itself. A check of thyroid hormone levels may be
beneficial in the preoperative evaluation.
Access- Due to several
problems including obesity and lack of muscle mass, individuals with PWS
may pose difficulties with insertion of an intravenous line. A stable IV
line should be present in any individual undergoing anesthesia.
Problems- Individuals with
PWS are more prone to emotional outbursts, obsessive-compulsive behaviors,
and psychosis. They may be on extensive psychotropic medication, and the
possible interaction of these medicines with anesthesia should be
Deficiency- All individuals
with PWS should be considered growth hormone deficient. The FDA has
recently recognized a diagnosis of PWS as an indication for growth hormone
therapy. Growth hormone deficiency does not appear to alter cortisol
release in response to stress; so steroid supplementation is not
necessary. Individuals with PWS who are not on growth hormone treatment
may have smaller airways than would be expected for their body size.
anesthesia may be due to
somnolence and a
component of central
apnea. For typical
consideration should be
given to an overnight
As mentioned above, a
majority of the problems
are due to obesity,
central and obstructive
apnea, but weak muscle
tone and chronic
aspiration may also play
a role in post
Individuals with PWS can safely undergo
anesthesia. Risks are related to their general health before the procedure. The
majority of complications do not appear to come from general anesthesia, which
is always closely monitored, but from poorly monitored conscious sedation. Only
a physician familiar with the patient and their individual medical needs should
make valid medical decisions.