Möbius sign

Description

Möbius sign: Diagnostic test in patients with Morbus Basedow (Graves disease) – the inability to maintain ocular convergence in the presence of hyperthyroidism.


History

1883Paul Julius Möbius first drew attention to finding of ‘incomplete convergence’ in cases of Basedow disease [1883;CC:100]

1886 – Möbius went on to discuss “…the sign in more detail on the basis of the examination of 10 patients, 8 of whom demonstrated a varying severity of the finding“. [1886;CCXII:136-138]

1891 – Möbius reviewed the clinical signs, symptoms and related pathology since the original description of diffuse toxic goitre and added further to his original description of the insufficiency of convergence [1891;1 (5-6):400-444]

Möbius translated reasoning for his sign

All other movements of the eyeballs are normal, but if the patient is to look at a nearby object (such as the tip of his nose or a finger held in front of his face), the eyes look to the right or to the left, and only one eye sees the object. This is seen most prominently when the patient is asked to first look at the ceiling and then at his own nose.

On looking at a finger moved toward the patients nose, the eyes converge to a point that varies between patients and at different times for the same patient. After this point, only one of the eyes fixates onto the object, whilst the other abducts to align in parallel with the adducted eye’s axis.

Whilst the eyes converge, the patient complains of eye strain. They are not however aware of the abnormal movements, nor do they suffer with double vision. The inability to converge is not directly related to the degree of exophthalmos. It also occurs without Basedow disease.

Charcot et al, corroborate my findings but have described them as ‘rare’ occurrences. In my experience over the past years, its incidence is less frequent than I had originally thought, however it does occur in most cases of Basedow’s disease, if only to a mild degree.

The insufficiency is not a real paralysis, neither is it caused by the exophthalmos. Exophthalmos does limit eye movements. Eye movements are also weakened at the onset of Basedow disease. The weakness is seen at the earliest during convergence, the most strenuous of the eye movements.Möbius 1891;1(5-6):402


Associated Persons


Alternative names

  • Weakness of eye convergence

References


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Posted by Dr Mike Cadogan

Emergency physician with a passion for medical informatics and medical education/textbooks. Asynchronous learning #FOAMed evangelist | @sandnsurf | + Mike Cadogan | LinkedIn

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