Anesthesia Concerns


In general, anesthesia is deemed safe forindividuals with WS, as long as a preanesthetic assessment is adequately performed. 

Guidelines, including the preanesthetic assessment, have been prepared by medical professionals working with individuals with Williams syndrome. These guidelines are presented below for reference.

Williams Syndrome and Anesthesia in a Large Unselected Cohort

Susan Nicholson, MD, Dept. of Anesthesia; and Kelli Deering and Paige Kaplan, MD, Division of Genetics, Children's Hospital of Philadelphia, Univ. of PA School of Medicine


Children and adults with Williams Syndrome (WS), a contiguous gene deletion syndrome, have medical issues that require procedures that should be done under general anesthesia. There is a perception that anesthesia carries greater risks in WS patients, arising from a number of isolated case reports published between 1961 and 1996 describing sudden death in 19 children with WS and congenital heart disease (CHD) who had undergone procedures both with and without anesthesia. The mechanism of death is incompletely understood.


A retrospective chart review of all the WS patients in this tertiary care children's hospital was done to evaluate the patients who had received an anesthetic in this hospital. 26 WS patients with CHD, ranging from mild to severe, between 6 months and 19 years of age underwent 60 surgical and cardiac catheterization procedures during a 13 year period (1987 to 2000).


There was a single adverse patient occurrence in an 18 month old boy with severe distal branch pulmonary stenosis and pulmonary hypertension. On emergence from anesthesia and tracheal extubation, his SpO2 fell, resulting in bradycardia. Resuscitative efforts, including chest compressions, administration of pharinacologic agents and reintubation were instituted with prompt return to baseline and full recovery.


Anesthesia can be safely administered to children with WS and CHD. A preoperative assessment to delineate the physiologic implications of the CHD, anesthetic care provided by a pediatric cardiac anesthesiologist who maintains the physiologic parameters within a narrow range, availability of resuscitative drugs/equipment, expeditious performance of the procedure with vigilance extending into the postoperative period enable children and adults with WS to benefit from anesthesia for their procedures.

The Preanesthetic Assessment of the individual with Williams syndrome

Dr. Lynn White

Growing awareness among health professionals involved in the care of children and adults with Williams syndrome (WS) has prompted formulation of guidelines for routine screening tests to monitor for diseases commonly encountered in this syndrome.

Many WS individuals undergo sedation or general anesthesia for diagnostic radiologic procedures, cardiac catheterization or surgical procedures. Surgeries frequently include strabismus correction, hernia repair, ear tubes and cardiovascular operations. During the past five years, literature in the form of case reports has recounted untoward events on induction of anesthesia, particularly in WS children with heart disease. This has caused reasonable concern about the kind of preoperative screening that needs to be done prior to an elective procedure. It is vital that the parents educate the anesthesiologist about their child's particular set of problems in a non-pressured setting. This is best arranged as a preanesthetic visit, usually within a week prior to the scheduled operation. It is now common practice in numerous medical centers nationwide for patients with potentially complex medical management to have preoperative evaluations with input from the appropriate specialists.

If parents or guardians of a child or adult with WS are not offered this option, it is best to discuss the possibility of scheduling such a meeting with the primary physician. Ideally, the primary physician would coordinate all patient records, including subspecialty visit reports and make this information available to pertinent participants in the individual's care. Often, however, the responsibility of collecting important data falls on the parents; thus, it is important to understand which items are most crucial prior to an operative procedure.

The problems of particular concern to the anesthesiologist include those related to a patient's cardiovascular system, kidney function, airway anatomy, metabolic status, joint mobility and level of cognitive functioning.

Taking these considerations individually, the cardiovascular system is first and foremost. Problems with the heart, great vessels and blood pressures are particularly prevalent in WS. Therefore, a cardiologic evaluation within the 12 months preceding surgery is desirable and records from the cardiologist should be requested for the anesthesiologists review. Copies of EKG'S, echocardiograms, chest x-rays (if available) and cardiac catheterizations (if appropriate) should be provided.

The airway problems in WS concern the potential difficulty in placing an endotracheal tube for general anesthesia in the WS individual with an underdeveloped lower jaw. Dental problems, including brittle or loose teeth can compound this difficulty. These features are best noted when the anesthesiologist performs a brief, specific physical exam during the preoperative visit.

The patient's intellectual and emotional profile will dictate the method of premedication and potentially the method of anesthetic induction used. The parents can be very helpful in supplying information that can be used to allay the WS individuals anxiety.

Kidney function tests and any records of urinary tract disease should be made available. Calcium derangements may be associated with urinary tract disorders and results of any calcium testing (if appropriate in a given individual) should be provided.

Joint contractures involving limitation of motion should be pointed out so that proper precautions can be taken with padding and positioning for the procedure. Any patient or family history of unusual reaction to anesthetics needs to be highlighted. In the individual with WS, a history of previous surgeries and responses to anesthetics can be very helpful. Any adverse reactions to medications should be reported and a list of current medications provided.

With a working knowledge of the WS patients history, recent subspecialty evaluations and appropriate lab data, an anesthesiologist can plan and individualize the anesthetic, type of monitoring equipment required and anticipate potential problems. Parents and guardians of WS individuals are a tremendously valuable resource to the treating physicians and should be informed participants in the process for providing safe intervention for their children.


Notes on Cardiac Catheterization and Anesthesia

Dr. Paul Wang & Ursula Bellugi

We all know that no medical procedure is 100 % safe, so no procedure should be done unless it is truly needed. Unfortunately, many children with Williams syndrome do need surgical procedures and/or cardiac catheterization. Two possible complications relating to surgery and catheterization have recently come to light. Although both are rare, they are worth knowing about.

It now appears that a small number of children with Williams syndrome can have narrowing of the coronary arteries. These are the arteries that go from the aorta to the heart muscle itself. (These same arteries are narrowed in adults with atherosclerosis, but for a different reason.) All the WS kids who have had 'Coronary Artery Stenosis' also had SVAS (Supravalvular Aortic Stenosis), but that may not hold up as more cases are discovered. If severe, coronary narrowing can cause 'myocardial ischemia' - lack of blood to the heart itself - and the possibility of permanent damage to the heart. Some of the children with coronary stenosis that we have seen did have damaged, scarred hearts. While an EKG might show evidence of ischemia or damage that has occurred already, it is very difficult to diagnose coronary narrowing except by doing a catheterization.

Coronary artery stenosis can cause complications, including heart attack, during the catheterization procedure. Therefore, it is important that your cardiologist be aware of this possibility beforehand. Also, it is advised that "non-ionic contrast agents" be used during the catheterization, rather than "ionic agents". This could help reduce the risk of the procedure itself. A good reference is by EE Conway, J. Noonan, RW Marion, & CN Steeg, in Journal of Pediatrics, October 1990, vol. 117, pp. 593-595.

At the 1990 convention in Boston, one parent reported that her child had "Malignant Hyperthemia". This is a very rare complication of anesthesia in which the body temperature rises extremely quickly and extremely high soon after anesthesia is started. We are aware of another case of malignant hyperthermia in a child with WS. Also a journal article has been published about another child with WS who developed Masseter Spasm, which sometimes precedes malignant hyperthermia. In masseter spasm, the jaw muscles tighten and force the mouth closed.

Although treatable, malignant hyperthermia is potentially very serious. It sometimes runs in families, and it seems to be more frequent during surgery for strabismus, which many kids with Williams have. The anesthesia drugs most frequently associated with malignant hyperthermia are "succinycholine" and "halothane" (But even with these drugs, the occurrence is very rare). Again, the important thing is that the anesthesiologist be made aware of the association between Williams syndrome and malignant hyperthermia, so that appropriate precautions and the use of other anesthetic drugs can be considered. The journal article referencing this information is by J Patel & MJ Harrison, Anaesthesia, 1991, vol. 46, pp. 115-116 If you have any unanswered questions about coronary stenosis or malignant hyperthermia, be sure to bring them up with your child's regular physician, cardiologist or anesthesiologist.


Williams Syndrome: Masseter Spasm During Anesthesia

J. Patel, MB, ChB, Registrar, Department of Anaesthesia, M.J. Harrison, FFARCS, Specialist, Department of Anaesthesia, New Zealand. Accepted 29 April 1990


A 4 year old boy with Williams syndrome developed masseter spasm after halothane and suxamethonium. He did not develop malignant hyperthermia; the surgery was accomplished with a nontriggering anaesthetic and no further problem.

Williams syndrome is a very rare disease associated with an elfin face, mental retardation and cardiovascular anomalies. The latter can take the form of supravalvular aortic stenosis and/or pulmonary supravalvular stenosis. All patients have the same characteristic facial appearance, partly determined by the mandibular hypoplasia. There are various dental anomalies including hypoplastic teeth. Idiopathic hypercalcemia in infancy is thought to be associated with the syndrome. The aortic stenotic lesions seen in idiopathic hypercalcemia and in experimental vitamin D intoxication are similar and it has been suggested that there might be a metabolic disorder in utero.

Case History

A 4-year-old Caucasian boy who weighed 15 kg with Williams syndrome was presented for correction of left strabismus. His exercise tolerance seemed to be normal and he had had an uneventful general anaesthetic for bilateral herniorraphy. Tracheal intubation was considered potentially difficult because he had protruding top teeth and a relatively hypoplastic mandible. He was premedicated with diazepam 5 mg by mouth since he was known to be of a difficult temperament. Sodium citrate 7.5 ml was given before anesthesia which was easily induced with halothane and nitrous oxide in oxygen. The trachea was intubated with a 4-mm oral Rae tracheal tube but he was subsequently extubated because of an excessive leak around the tracheal tube. He developed intractable laryngospasm during laryngoscopy for re-intubation that required a dose of muscle relaxant. Suxamethonium 10 mg was given but seemed to be ineffective and a further 5 mg was given.

The Masseter spasm was evident after the second dose and consequently the halothane was discontinued. The masseter spasm resolved spontaneously over a period of about a minute, and vecuronium 1 mg was given to facilitate intubation. The 4.5-mm tracheal tube was a tight fit and he was extubated again and re-intubated with the original tube. A throat pack was inserted. Anaesthesia was maintained with nitrous oxide in oxygen and 5 mg fentanyl. He required no further muscle relaxant. No other features of malignant hyperthermia were seen.

The patient showed no signs of awareness during the procedure and was extubated awake at the conclusion of the surgery. There were no postoperative problems. Biochemistry performed a week after operation was within normal limits. The creatine kinase was 122 IU/litres. A muscle biopsy was not performed nor was the urine myoglobin measured.


There is only one report in the anaesthetic literature on Williams syndrome. Laryngoscopy was not difficult in our case although intubation problems should be considered because of the dysmorphic features already mentioned. Contrary to the report of van Beuren el al this patient had a difficult temperament. Hypotonia may be present in Williams syndrome, and this disorder of muscle tone should warn of a possible interaction with anaesthetic agents. There are, however, no data that suggest an increased incidence of masseter spasm or malignant hyperthermia in these patients. The incidence of masseter spasm varies depending on the anaesthetic technique. It is higher in patients induced with halothane and suxamethonium than those induced with thiopentone and suxamethonium. An incidence of about 1 % in children anesthetized with halothane and suxamethonium has been reported. It is well recognized that the incidence of masseter spasm is greater in patients undergoing strabismus surgery. Carroll found a fourfold difference when comparing the incidence in strabismus patients with patients without strabismus.

Christian et al. found a much lower incidence of masseter spasm in children, approximately 1 : 100,000 but they assumed that they were reporting a different condition or reporting a more severe degree of the same condition. There is some debate in the literature whether masseter spasm should still be regarded as an early; sign of malignant hyperthermia.

Van der Spek et al. measured mouth opening after induction of muscle relaxation with suxamethonium, pancuronium and vecuronium in children and found there was a highly significant reduction in mouth opening and increase in jaw stiffness with suxamethonium (p < 0.0001). Patients who received pancuronium or vecuronium did not show this effect. It would appear that an increase in masseter muscle tone with suxamethonium is normal and an exaggerated response may clinically be taken to be masseter spasm.

This child exhibited excessive masseter tone after the use of halothane and suxamethonium: This may have been an exaggerated normal response, but in the presence of other congenital abnormalities of the musculoskeletal system the danger of malignant hyperthermia was considered a real possibility and appropriate action taken.