2026 ICD-10-CM Diagnosis Code G71.19Other specified myotonic disorders

AHRQ’s CCSR groups this code into broader clinical categories.

• Myotonia

  prolonged failure of muscle relaxation after contraction. this may occur after voluntary contractions, muscle percussion, or electrical stimulation of the muscle. myotonia is a characteristic feature of myotonic disorders.

• Myotonia Congenita

  inherited myotonic disorders with early childhood onset myotonia. muscular hypertrophy is common and myotonia may impair ambulation and other movements. it is classified as thomsen (autosomal dominant) or becker (autosomal recessive) generalized myotonia mainly based on the inheritance pattern. becker type is also clinically more severe. an autosomal dominant variant with milder symptoms and later onset is known as myotonia levior. mutations in the voltage-dependent skeletal muscle chloride channel are associated with the disorders.

• Myotonic Disorders

  diseases characterized by myotonia, which may be inherited or acquired. myotonia may be restricted to certain muscles (e.g., intrinsic hand muscles) or occur as a generalized condition.

• Myotonic Dystrophy

  neuromuscular disorder characterized by progressive muscular atrophy; myotonia, and various multisystem atrophies. mild intellectual disability may also occur. abnormal trinucleotide repeat expansion in the 3' untranslated regions of dmpk protein gene is associated with myotonic dystrophy 1. dna repeat expansion of zinc finger protein-9 gene intron is associated with myotonic dystrophy 2.

• Osteochondrodysplasias

  abnormal development of cartilage and bone.

• Isaacs Syndrome

  a rare neuromuscular disorder with onset usually in late childhood or early adulthood, characterized by intermittent or continuous widespread involuntary muscle contractions; fasciculation; hyporeflexia; muscle cramp; muscle weakness; hyperhidrosis; tachycardia; and myokymia. involvement of pharyngeal or laryngeal muscles may interfere with speech and breathing. the continuous motor activity persists during sleep and general anesthesia (distinguishing this condition from stiff-person syndrome). familial and acquired (primarily autoimmune) forms have been reported. (from ann ny acad sci 1998 may 13;841:482-496; adams et al., principles of neurology, 6th ed, p1491)

• Myotonic Disorder

  an inherited or acquired, localized or generalized disorder affecting the muscles. it may be associated with abnormalities in the chloride or sodium channels of the muscles. it is characterized by delayed muscle relaxation following stimulation or contraction. representative examples include myotonia congenita and myotonic dystrophy.

• Acute Motor and Sensory Axonal Neuropathy|Acute Motor And Sensory Axonal Neuropathy|Acute Motor-Sensory Axonal Neuropathy|Acute Motor-Sensory Axonal Neuropathy

  a subtype of guillain-barre syndrome that targets sensory motor axons, and is characterized by acute onset of quadriparesis, distal sensory loss, areflexia, and respiratory insufficiency.

• Acute Motor Axonal Neuropathy|AMAN

  a subtype of guillain-barre syndrome that targets motor axons, and is characterized by symmetric limb weakness, diffuse areflexia, facial and oropharyngeal muscle weakness, and respiratory insufficiency.

• Axonal Neuropathy

  any nerve disorder affecting the axon of a nerve.

• GAN wt Allele|GAN1|Giant Axonal Neuropathy (Gigaxonin) Gene|Gigaxonin wt Allele|KLHL16

  human gan wild-type allele is located in the vicinity of 16q24.1 and is approximately 65 kb in length. this allele, which encodes gigaxonin protein, is involved in both ubiquitination and neurofilament structure. mutation of the gene is associated with giant axonal neuropathy.

• Giant Axonal Neuropathy

  a rare inherited disorder affecting the neurofilaments. it is caused by mutations in the gan gene. it is characterized by the presence of abnormally large nerve cell axons. signs and symptoms include difficulty walking, sensory disturbances, lack of motor coordination and abnormal reflexes in the limbs.

• Spinocerebellar Ataxia, Autosomal Recessive, with Axonal Neuropathy 2|AOA2|Ataxia with Oculomotor Apraxia Type 2|SCAN2

  an autosomal recessive condition caused by mutation(s) in the setx gene, encoding probable helicase senataxin. it is characterized by juvenile onset progressive cerebellar ataxia, axonal sensorimotor peripheral neuropathy, and increased concentrations of serum alpha-fetoprotein. oculomotor apraxia is common, but is not always present.

• Myotonic Cataract

  a cataract occurring as a sequela of myotonic dystrophy.

Neuromuscular Disorders

Neuromuscular disorders affect your neuromuscular system. They can cause problems with:

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