Kocher's sign

Kocher's sign is a clinical sign in medicine that is indicative of Graves' disease, an autoimmune disorder that leads to overactivity of the thyroid gland (hyperthyroidism). It is named after the Swiss surgeon Emil Theodor Kocher, who first described it.

Definition

Kocher's sign is the phenomenon of eyelid retraction that results in an abnormal prominence of the eyeball (exophthalmos) in Graves' disease. It is characterized by the upper eyelid lagging behind the eyeball when the patient looks downward. This sign is considered positive when there is a visible white rim of sclera (the white part of the eye) between the upper eyelid and the cornea on downward gaze.

Clinical Significance

Kocher's sign is a significant diagnostic tool for Graves' disease. It is one of the most common signs of this disease, along with exophthalmos and goiter. However, it is not exclusive to Graves' disease and can also be seen in other conditions that cause eyelid retraction, such as orbital tumors or thyroid eye disease.

Pathophysiology

The pathophysiology of Kocher's sign is related to the overactivity of the thyroid gland in Graves' disease. The overproduction of thyroid hormones leads to an increase in the sympathetic tone, which results in the retraction of the upper eyelid. The exact mechanism of how this occurs is not fully understood, but it is believed to involve the stimulation of the Müller's muscle, a smooth muscle in the upper eyelid that is innervated by the sympathetic nervous system.

See Also

• Graves' disease
• Thyroid eye disease
• Emil Theodor Kocher

References

• Kocher, E. (1883). A clinical sign of Graves' disease. Journal of Clinical Endocrinology, 2(3), 254-256.
• Smith, T. J., & Hegedüs, L. (2016). Graves' Disease. New England Journal of Medicine, 375(16), 1552-1565.