An extraforaminal, far lateral, or extreme lateral disc herniation is defined as a disc herniation that does not extend into the spinal canal but instead causes compression of the nerve root in the neuroforamen or outside it1. Compared with intraspinal disc herniations, extraforaminal herniations are relatively rare but can cause the same symptoms. Extraforaminal disc herniations most commonly occur in the setting of a lumbar disc herniation.
Epidemiology
In a case series of 204 surgically treated lumbar disc herniations, 24 were located in the extreme lateral position2. Of these 24 far lateral disc herniations, 75% were located at the L4/5 level, 4% at the L3/4 level, and 21% at the L2/3 level3. Additional case series show a similar distribution, with extreme lateral disc herniations accounting for approximately 10%4.
Imaging
The gold standard for the diagnosis of extraforaminal disc herniations is MRI imaging.
References
Abdullah, A. F., et al. "Extreme-lateral lumbar disc herniations: clinical syndrome and special problems of diagnosis." Journal of neurosurgery 41.2 (1974): 229-234. ↩ ↩ ↩ ↩ ↩ ↩
Abdullah, Adel F., et al. "Surgical management of extreme lateral lumbar disc herniations: review of 138 cases." Neurosurgery 22.4 (1988): 648-653. ↩ ↩