Bielschowsky's head tilt test is a medical test

Medical test

A diagnostic test is any kind of medical test performed to aid in the diagnosis or detection of disease. For example:* to diagnose diseases, and preferably sub-classify it regarding, for example, severity and treatability...

 to detect damage to the IVth cranial nerve

Trochlear nerve

The trochlear nerve is a motor nerve that innervates a single muscle: the superior oblique muscle of the eye....

 leading to a palsy of the superior oblique muscle

Superior oblique muscle

For the abdominal muscle see: Abdominal external oblique muscleThe superior oblique muscle, or obliquus oculi superior, is a fusiform muscle originating in the upper, medial side of the orbit which abducts, depresses and internally rotates the eye...

 of the eye

Human eye

The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...

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Patients with superior oblique palsy on one side experience double vision

Diplopia

Diplopia, commonly known as double vision, is the simultaneous perception of two images of a single object that may be displaced horizontally, vertically, or diagonally in relation to each other...

, which is improved or even abolished by tilting the head towards the shoulder on the unaffected side. Tilting the head towards the shoulder on the affected side will make the double vision worse by causing increased separation of the two images seen by the patient.

The test is named after Alfred Bielschowsky

Alfred Bielschowsky

Alfred Bielschowsky was a German ophthalmologist. His specialty was physiology and pathology of the eye, particularly in regards to research of eye movement, space perception and diagnosis of oculomotor anomalies....

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