The transforaminal approach is less traumatic, but has anatomical restrictions craniocaudally.
The interlaminar approach has wider application craniocaudally, but is more traumatic.
So whenever possible, I would prefer transforaminal approach, unless it is technically not possible by anatomical restrictions.
Anatomical restrictions for the transforaminal approach:
*With foraminal or extraforaminal pathology: No limits.
*With disc herniation within the spinal canal (central or paracentral): Limits: from the caudal edge of the cranial pedicle to the middle part of the caudal pedicle.
*With lateral recess stenosis: Limits: from the caudal edge of the cranial pedicle to the cranial edge of the caudal pedicle
*For central stenosis by dorsal pathology: Cannot be applied.
*L5-S1 pathology in a male with high iliac crest: Cannot be applied, except with iliac crest drilling.
*L5-S1 cranially migrated disc: Cannot be applied.
Anatomical restrictions for interlaminar approach:
*Far lateral pathology (foraminal and extraforaminal pathology): Cannot be applied.
*An exception is foraminal pathology in contralateral interlaminar approach.
General preferences for disc herniation:
* L5-S1 disc herniation: interlaminar approach is preferred, especially if axillary.
* High degree of disc migration: interlaminar is preferred, and sometimes mandatory.
* Above L4-L5: transforaminal is preferred, but with good planning to avoid visceral injury.
* Large central prolapsed disc: transforaminal is preferred, to avoid neural retraction.
* Foraminal prolapsed disc: transforaminal is preferred.
* Extraforaminal prolapsed disc: transforaminal is mandatory.
General preferences for stenosis surgery:
* Central stenosis by dorsal pathology: interlaminar is mandatory.
* Pure lateral recess stenosis: interlaminar is preferred.
* Combined lateral recess stenosis and foraminal stenosis: transforaminal is preferred.
* Pure foraminal stenosis: transforaminal is preferred.
* Foraminal stenosis in L5-S1 in male with high iliac crest: contralateral interlaminar approach.
Conclusion:
I tried my best to summarize the transforaminal and interlaminar approaches. Please correct me if I have any mistake, and add to my summary if you have any addition.