Transition zone (nerve)

Last revised by Rohit Sharma on 16 Jan 2025

The transition zone of a nerve, also known as the Obersteiner-Redlich zone, describes a region of a few millimeters where the myelin sheath changes from a central to peripheral type as enveloping glial cells are replaced by Schwann cells.

Transition zones are of variable length, not a sudden transition, but rather, the central myelin component extends further in the center of the nerve than on the periphery. The location of the transition zone is also variable distance from the nerve root entry zone, depending on the cranial nerve and differing to a degree between individuals 1,4,5,7-9:

The transition zone is susceptible to mechanical irritation and is implicated in neurovascular compression syndromes such as trigeminal neuralgia (CN V), hemifacial spasm (CN VII), vestibular paroxysmia (CN VIII) and glossopharyngeal neuralgia (CN IX). The location of the transition zone relative to the root entry zone for a cranial nerve can be useful in understanding whether a contacting vessel is likely to cause neuralgia or not 1.

The transition zone is often attributed to being the site of origin of vestibular schwannomas, however this has been shown to be an erroneous myth across multiple studies 2,3,6.

The zone is eponymously attributed to Emil Redlich (1866-1930) and Heinrich Obersteiner (1847-1922), Austrian physicians.

Cases and figures

  • Figure 1
:

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.