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Clinical Classification for Myasthenia Gravis

Purpose: To classify a myasthenic patient using the stages of Osserman and Genkins.

Description

Osserman and Genkins separated patients with myasthenia gravis into different clinical groups based on the extent and progression of muscle involvement. This correlates with the response to therapy and prognosis.


Class

Findings

Adult Group

asymptomatic

no signs or symptoms

0

ocular involvement only

localized to ocular muscles, and may involve only 1 eye

ptosis and diplopia usually present

if there is no spread to other muscles groups after 2 years from onset, then usually nonprogressive

I

mild generalized

slow onset

presentation often with ocular symptoms

gradual progression to involve bulbar and skeletal muscles

respiratory muscles are not involved

IIA

moderate generalized

gradual onset

presentation often with ocular symptoms

progression to a more severe generalized involvement of the bulbar and skeletal muscles

respiratory muscles are not involved

IIB

acute fulminating

rapid onset of severe bulbar and skeletal muscle weakness; disease progresses over a few months

early involvement of the respiratory muscles

III

late severe

severe, progressive symptoms starting at least 2 years after the onset of myasthenia

IV

 

where:

• The common thread for Group IIA and IIB is the absence of respiratory muscle involvement.

• Bulbar symptoms include dysarthria, dysphagia, chewing weakness and dyspnea.

 

Adult Group

Prognosis

0

excellent

I

excellent

IIA

mortality very low, with good response to drug therapy

IIB

mortality low; response to drug therapy may be suboptimal

III

mortality high and response to drugs is poor

IV

mortality high and response to drugs is poor

 

A modification of the classification (Abt et al, 2001) uses the same groups but assigns a different Roman numeral, as follows:

 

Original Group

Modified Group

0

0

I

I

IIA

II

IIB

III

III

IV

IV

V

 

Pediatric types:

(1) transient neonatal: a self-limited condition in infants born to myasthenic mothers that may last up to 6 weeks after delivery before disappearing, due to transplacental passage of antibodies from the mother

(2) juvenile: myasthenia is not present in the mother, but may be present in siblings or close relatives; this is classified similar to adult onset myasthenia

 


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Specialty

Objective

ICD-10