May Case Of The Month

Title:  Spinal muscular atrophy

An anesthesiologist was about to provide anesthesia care for a baby with spinal muscle atrophy (SMA), and called the MH Hotline to see if inhalation agents were safe in a patient with SMA. My response was that I was not aware of an association of SMA with MH, and I knew of no other reason to avoid inhalational anesthetic agents.

   

 Question 1.  What diseases are associated with MH?

                    A. King-Denborough Syndrome

                    B. Central Core Disease

                    C. Minicore myopathy

                    D. All of the above

 

                 

     Question 2. Patients with spinal muscle atrophy can safely be anesthetised with general (inhalational) or regional anesthesia.

                    A. True

                    B. False

 

                 

 

      Question 3. What associated findings may be seen in the SMA patient that would influence your anesthetic plan?

                     A. Congenital heart abnormalities

                     B. Dysphagia

                     C. limited jaw opening

                     D. Respiratory compromise

                     E. All of the above

 

                  

 

         Question 4. Is Muscular Dystrophy associated with MH?

                       A. Yes

                       B. No

                       C. Probably not

 

          

 

          Question 5. Should succinylcholine and inhalation agents be avoided in patients with Muscular Dystrophy?

                         A. Yes

                         B. No

                         C. Probably

 

Answers

1.  d
2.  a
3.  e
4.  c or b
5.  a and c

Question 1: Diseases associated with MH are: King Denborough Syndrome, central core disease, and minicore myopathy, all of which have RyR1 defects.

 Question 2 and 3: Spinal Muscular Atrophy (SMA) is a motor neuron disease with progressive hypotonia and muscular weakness, especially proximal muscles of back, shoulders and hips. It is autosomal recessive due to a missing mutated gene survival motor neuron 1 (SMA1). Incidence is 1/6000 babies. They have dysphagia, respiratory difficulties, , pneumonia, weak cough, congenital heart defects in 20 cases reported, limited jaw opening in some. They are normal intellectually, bright and social.  There are 4 types. Type I: acute infantile SMA, early onset, floppy, death by 2 years from respiratory causes, Werdnig-Hoffman disease.

             Type II: Chronic infantile SMA, normal first 6 mos, never able to walk, diagnosed 6-12 months, can stand with braces, can live into fourth decade.

             Type III: Kugelberg-Welander, juvenile spinal muscular atrophy, onset 1 year to adolescence, can walk, minimlal feeding or swallowing problems, finger tremors

              Type IV: Adult onset, after age 35, less common, slow onset, no swallowing problems.

            Anesthesia with both general and regional reported sucessfully, tolerated inhalation agents well. No reported relation to MH. 

 

     Questions 4 and 5: Muscular dystrophy.   For years is was thought that there was an association between Duchenne muscular dystrophy and MH. Now there is evidence against the association discussed in Jason Hayes article in Pediatric Anesthesia 2008, 18: 100-106. It is still wise to avoid succinylcholine and inhalation agents in DMD due to the reports of hyperkalemic cardiac arrest following Sux and reports of anesthesia induced rhabdomyolysis (AIR) after exposure to inhalation agents. This is controversial.

 

James Chapin, MD

University of Nebraska Medical Center

Omaha, NE  68198