Thomsen’s disease (myotonia congenita)

Published on 05/05/2015 by admin

Filed under Internal Medicine

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1356 times

67 Thomsen’s disease (myotonia congenita)

Instruction

Look at this patient.

Salient features

History

• Ask the patient whether or not there is any seasonal variation in symptoms: myotonia is worse in winter from the cold.

• Take a family history (inheritance is usually autosomal dominant; gene on long arm of chromosome 7).

Examination

• Diffuse muscle hypertrophy

• Myotonia, which may be apparent while shaking hands with the person. (The myotonia displays a warm up phenomenon, in which the myotonia decreases or vanishes completely when repeating the same movement several times.)

Note: Know the phenotypic patters of muscle disorders.

Diagnosis

This patient has diffuse muscular hypertrophy with myotonia (lesion) caused by Thomsen’s disease (aetiology).

Advanced-level questions

How is the disease recognized in infancy?

Myotonia is present from birth and may be recognized by the child’s peculiar cry. Also noticed in early infancy are difficulty in feeding and inability to reopen the eyes while having the face washed.

When does muscle hypertrophy manifest?

It is usually apparent in the second decade.

What is the cause of muscle hypertrophy?

It is caused by almost continual involuntary isometric exercise.

What is the life expectancy in such patients?

These patients have a normal life expectancy.

What drugs would you use to ameliorate the myotonia?

Procainamide, quinidine.

What do you know about genetics of this disease?

It can be inherited as either an autosomal dominant (Thomsen’s disease) or recessive (Becker myotonia) trait. Myotonia congenita is a specific inherited disorder of muscle membrane hyperexcitability caused by reduced sarcolemmal chloride conductance as a result of mutations in CLCN1, the gene coding for the main skeletal muscle chloride channel ClC-1 (Neurology 2000;54:937–42). The disorder may be transmitted as either an autosomal dominant or recessive trait, with close to 130 currently known mutations.

In which other conditions is myotonia seen?

Myotonia can be a presenting sign of:

• myotonic dystrophy

• non-dystrophic myotonias, in which mytonia is caused by dysfunction of:

• channels for chloride (in myotonia congenita) or
• sodium channels (in paramyotonia congenita, potassium-aggravated myotonia and hyperkalaemic periodic paralysis with myotonia)

• myopathies (acid maltase deficiency, polymyositis, myotubular myopathy)

• following administration of drugs such as clofibrate, colchicine

• rarely, denervation of any cause.

AJT Thomsen (1815–1896) was a Danish physician who described this condition in his family and himself in 1876.

Related posts:

Default ThumbnailSixth cranial nerve palsy Osteoarthrosis Cataracts Ebstein’s anomaly Paget’s disease Erythema nodosum