April 2007 Case of the Month

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Topic:  Family history of exercise-induced rhabdomyolysis

A 15-month-old healthy male presents for myringotomy and ear tube insertion because of recurrent otitis media.  His father, who is generally healthy, reports an episode of exercise-induced rhabdomyolysis (EIR) approximately one year ago. Further questioning revealed that the father had this episode after vigorous exercise during a relatively unfit condition.

1.   Which types of persons are predisposed to EIR?

A. Certain patients with MH susceptibility
B. Patients with McArdle’s Disease
C. Normal patients who are unaccustomed to vigorous exercise
D. All of the above

2.  What is the classic symptom triad of rhabdomyolysis?

A. Vomiting, abdominal pain, weakness
B. Weakness, muscle pain, brown urine
C. Headache, vomiting, weakness
D. Hallucinations, headache, vomiting

3.  What preoperative lab studies are appropriate in this patient?

A. Hemoglobin
B. Creatine phosphokinase (CK)
C. Caffeine-halothane contracture test (CHCT)
D. All of the above

4.  Which anesthetic induction technique is most appropriate for this patient?

A. Sevoflurane, nitrous oxide
B. Nitrous oxide, propofol
C. Ketamine
D. Any of the above

Answers and Narrative:
1. D. EIR is most commonly seen in normal patients after vigorous exercise.  There are, however, a number of medical entities that predispose to EIR, including McArdle’s Disease, sepsis, phosphofructokinase deficiency, phosphoglycerate mutase deficiency, carnitine palmityl transferase deficiency, and exposure to certain toxins (e.g., ethanol, amphetamines, ecstasy, etc.).
 
2. B. The classic triad of rhabdomyolysis consists of muscle pain, weakness, and brown urine. However, only about 50% of patients actually present with this triad. The muscle pain and weakness are caused by muscle damage, swelling, and inflammation, and the brown urine represents myoglobinuria, as a result of muscle breakdown. Rhabdomyolysis is confirmed by dipstick positive urinalysis without the presence of red cells and an extremely elevated blood creatine phosphokinase (CK) level.

3. B. Hemoglobin is not appropriate for an otherwise healthy child prior to elective surgery. Although some patients with MH susceptibility may have had episodes of EIR, the CHCT is only appropriate for older children with sufficient muscle mass. A CK level may prove to be useful as there are some inherited metabolic diseases (e.g. McArdle’s) in which patients are nonsymptomatic in everyday life but may have an underlying baseline CK elevation. This may be the only clue to a muscle disorder and MH susceptibility.
4. D. Any of the standard induction techniques may be appropriate for this patient, depending on the anesthesiologist’s index of suspicion for MH susceptibility. Sevoflurane, which is a known MH-triggering agent, may be administered if the patient is not considered to be MH susceptible. This would be the case if the patient’s father had a clear isolated episode of EIR, with a normal baseline CK, or a confirmed negative CHCT. Otherwise, the patient may be considered MH susceptible and any nontriggering anesthetic technique is acceptable.

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Ronald S. Litman, D.O., F.A.A.P.
Attending Anesthesiologist
The Children's Hospital of Philadelphia
Associate Professor of Anesthesiology and Pediatrics
University of Pennsylvania School of Medicine
Philadelphia, Pennsylvania