Title: Should this child be treated as MH susceptible?
This 3 year old is scheduled for bilateral exam of his ears and adenoidectomy possible tonsillectomy for recurrent otitis and sleep apnea. His past medical history also included reflux and asthma. He has not required ER visits or steroids for asthma. He has blue circles under his eyes and his breath sounds are clear when he opens his mouth wide.
Mom reports that her brother had a problem with anesthesia that was followed up with a muscle biopsy on his leg. What can you do to get more information?
The brother calls back to read the note his anesthesiologist had written about the event.
This 6 yr old boy was fasted for >8 hours prior to GA for umbilical hernia repair.
im meperidine, hydroxyzine and atropine were given Anesthesia was induced with halothane and nitrous oxide by mask. An IV was started and 1.5 mg/kg of succinylcholine with 10 mcg/kg of atropine was injected IV.
Considerable jaw rigidity made placement of the ETT difficult. The limbs appeared to be relaxed.
Heart rate was 120/min and temperature was 37.5. End-tidal carbon dioxide was not documented.
ABG showed pH 7.26, pO2 143, pCO2 37, BE -10 mM.
Surgery was cancelled and dantrolene 1 mg/kg was given IV.
Initial post-op creatine kinase (CK) was 326 iu (normal 30-170).
Within 12 hours CK increased to 40,000 iu. This decreased over the following 48 hours.
What to do now?
Brother contacted the North American MH Registry (NAMHR), # 888-274-7899, and arranged to send a signed copy of the Release of Information Form (see www.mhaus.org; MH Registry, downloads tab) to the NAMHR instructing that they release his CHCT results to you.
This test was performed 15 years ago at a MH testing center that is now closed.
The results are:
Detailed neurologic exam by a neurologist found no evidence of a myopathy and electromyography of back and legs was normal.
Resting CKs in the proband and his parents were normal.
The CHCT was performed and interpreted in accordance with the standards of the North American MH Group. Six muscle strips were examined in increasing concentrations of caffeine. Five strips were examinded in halothane. The results were interpreted as normal.
Histologic and histochemical exams were also normal. Assay of carnitine palmitoyl transferase was normal.[See Anesthesiology 1992; 77:820 for more details of test results.]
No one in the family has had any symptoms of muscle disease or sensitivity to heat, but they are given nontriggering anesthetics after learning of the anesthetic history of the brother.
We administered a small dose of
Questions 1:
What are causes of difficulty opening the mouth after succinylcholine administration during inhalation anesthesia?
1) light anesthesia
2) myotonia
3) temperomandibular joint disease
4) impending MH
5) seizure activity
Questions 2:
Put these common causes of rhabdomyolysis (or creatine kinase > 2,000) in a young boy in order of prevalence, most likely first.
1) viral or bacterial infection
2) dystrophinopathy
3) succinylcholine administration during inhalation anesthesia
4) malignant hyperthermia
Question 3:
Which of the following statements about diagnostic tests are true?
1) CK greater than 20,000 iu after an anesthetic that included succinylchoine is diagnostic of MH.
2) examination of the hotspots of the ryanodine receptor type one gene has confirmed MH susceptibility in families of individuals who died of MH or suffered fulminant episodes
3) a normal result on muscle contracture testing is the only current method that can definitively rule out the possibility that an individual is MH susceptible
4) the negative predictive value of the CHCT is greater than the positive predictive value of the CHCT
ANSWERS
Questions 1:
1, 2, 3, 4 are causes of jaw rigidity
Question 2:
3
Question 3:
2, 3, & 4
Barbara Brandom, MD
Children's Hospital of Pittsburgh of UPMC
Pittsburgh, PA
