Disc sequestration

Last revised by Ian Bickle on 30 Jul 2023

Sequestrated disc, also referred to as a free disc fragment, corresponds to extruded disc material that has no continuity with the parent disc and is displaced away from the site of extrusion. By definition, it corresponds to a subtype of disc extrusion.

The term "migrated" disc refers only to position and not to the continuity of disc substance. So, this term can be used when referring either to extruded discs that still have continuity or those without, i.e. sequestrated (e.g. disc extrusion migrated caudally, sequestrated disc migrated cranially).

History and etymology

The English word 'sequester' is uncommonly used in everyday speech but means to 'set apart' or 'set aside' 2. It is of course also used in the sense of a piece of dead bone set apart from the rest of the bone, i.e. a bony sequestrum, most commonly in chronic osteomyelitis 3.

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