(Becker disease, Thomsen disease)

Rare: 1/100.000 but 1/10,000 in Northern Scandinavia.

This mutation of the CLCN1 gene (7q35) results in a loss of function of the Cl- channels of the muscle membrane. This Cl- channel channelopathy of the muscle membrane is called Thomsen disease in case of autosomal dominant transmission or Becker disease in case of autosomal recessive  transmission. The myotonic response to percussion or hands shaking is easy to provoke and disappears in case of continuous muscle activity ("warm up" phenomenon) but is aggravated after a period of rest; there are no extramuscular manifestations.

Several types have been identified:

●        Thomsen disease [MIM 160 800, 118 425]: onset in childhood; the myotonia is primarily localized in the muscles of the  limbs that are often hypertrophied; the crises are generally not painful.

Two variants:

-        fluctuating congenital myotonia: starts later (end of first decade) and the crises of myotonia are more rare but painful and mainly located in the lower limbs

-        myotonia levior : begins during the second decade and the symptoms are less obvious; There is no associated muscle hypertrophy

●        Becker disease [MIM 255 700, 118 425]: clinical onset in the second decade (earlier diagnosis possible with EMG); more severe than Thomsen disease and reaches primarily the lower limbs. Sometimes episodes of proximal hypotonia  especially of the upper limbs. Sometimes muscular atrophy and high CK levels.

Some patients benefit from symptomatic treatment with mexiletine.

Anesthetic implications:

there is no risk of malignant hyperthermia even if positive contracture tests to caffeine  and halothane  have been reported. However, cases of intraoperative hyperthermia and one case of intraoperative hypermetabolic reaction similar to malignant hyperthermia (but without administration of any triggering agents !) have been reported. Avoid succinylcholine which can result in masseteric spasm, prolonged stiffness and a metabolic response resembling a malignant hyperthermia crisis. Avoid hypothermia and hypoglycemia and maintain the blood kaliemia at the upper limit of normal. When using a non-depolarising muscle relaxant, titrate the dose according to the neuromuscular monitoring, even if a normal response to rocuronium has been observed. Avoid neostigmine which can cause myotonia ; sugammadex has been used with success. While propofol has an antimyotonic effect in vitro and has been used without any problem in one case, some cases of myotonic crises caused by pain on injection of propofol have been described in patients with dystrophic myotonia (a similar but very different pathology)

References : 

-        Heiman-Patterson T, Martino C, Rosenberg H, Fletcher J, Tahmoush A.
Malignant hyperthermia in myotonia congenita.
Neurology 1988 ; 38 :810-2

-        Farbu E, Softeland E, Bindoff LA. 
Anaesthetic complications associated with myotonia congenita: case study and comparison with other myotonic disorders. 
Acta Anaesthesiol Scand 2003;47:630-4.

-        Mayhew J, Moreno L. 
Hyperthermia following anesthesia in a child with previously undiagnosed myotonia. 
Anesthesiology Review 1987; 14: 47-9

-        Haberer JP, Fabre F, Rose E. 
Malignant hyperthermia and myotonia congenita (Thomsen’s disease) (letter). 
Anaesthesia 1989;44:166.

-        Parness J, Bandschapp O, Girard T. 
The myotonias and susceptibility to malignant hyperthermia. 
Anesth Analg 2009, 109: 1054-64. 

-        Stourac SP, Krikava I, Seidlova J, Strazevska E, Huser M, Hruban L, Janku P, Gal R.
Sugammadex in a parturient with myotonic dystrophy (erroneous title: this report actually describes a case of Thomsen levior type  disease). Br J Anaesth 2013 ; 110 : 657-8.

-        Bandschapp O, Ginz HF, Soule CL et al. 
In vitro effects of propofol and volatile agents on pharmacologically induced chloride channel myotonia. 
Anesthesiology 2009; 111: 584-90.

-        Heatwole CR, Statland JM, Logigian EL. 
The diagnosis and treatment of myotonic disorders. 
Muscle Nerve 2013; 47: 632-48.

-        Hoppe  K, Lehmann-Horn F, Chaiklieng S, Jurkat-Rott K, Adolph O, Klingler W. µ
In vitro muscle contracture investigations on the malignant hyperthermia like episodes in myotonia congenital. 
Acta Anaesthesiol Scand 2013; 23:824-33

-        Bandschapp O, Iaizzo PA. 
Pathophysiologic and anesthetic considerations for patients with myotonia congenital or periodic paralyses. 
Pediatr Anesth 2013; 23: 824-33.

-        Anaesthesia and orphan disease: rocuronium and sugammadex in the anaesthetic management of a parturient with Becker’s myotonia congenital.
Eur J Anaesthesiol 2016; 33: 545-7

-        Stunnenberg BC, LoRusso S, Arnold WD, Barohn RJ, Cannon SC et al.
Guidelines on clinical presentation and management of nondystrophic myotonias.
Muscle Nerve 2020; 62:430-44.

Updated: December 2023