Bertolotti syndrome is a developmental abnormality wherein, the transverse process of the caudal most lumbar vertebrae is enlarged and shows pseudoarticulation with the sacral ala or ilium, leading to an uncommon cause of chronic lower back and gluteal region pain in young individuals.

Radiologists should try to recognize this condition, particularly regarding pseudoarticulation, as there is potential clinical significance due to the following factors:

• pseudoarticulation causes biomechanical stress - reduces mobility on the ipsilateral side or alternatively causes hypermobility on the contralateral side, leading to pain
• ipsilateral facetal arthropathy
• iliopsoas and quadratus lumborum muscle strain
• narrowed neural foramina by the dysplastic transverse process, causing nerve root compression
• disc herniation above the level of transitional vertebra
• pseudoarticulation may lead to a stress reaction, seen as edema or sclerosis

Apart from the above, identifying transitional vertebrae may prevent incorrect surgery.

Special thanks to Dr HT Gururaj