Multiple Bilateral Perineural Sleeve Cysts

A 51 year old male with low backache.  No neck pain. No radiating pain to any of upper limb.  No neuro deficit on clinical examination. No history of trauma.

Sagittal far lateral T2w section going through neural foramen of dorsal region spine show cystic signal intensity in the neural foramen with mild widening of corresponding neural foramen.  Sagittal and coronal MR Myelography image shows multiple bilateral cystic signal intensity along the nerve roots on either side of thecal sac.

Imaging wise : Bilateral Peri neural sleeve cysts.

In 1938 Tarlov first described cystic lesions of spinal nerve roots and introduced the term "perineural cyst". Perineural cyst (Tarlov’s cyst) is a cyst formation within the spinal nerve root sheath at the dorsal root ganglion. Most common in sacral region, may involve the cervical, thoracic or lumbar roots and are often multiple.
Associated with corresponding neural foraminal widening or focal scalloping of wall of bony spinal canal.
Exact mechanism not known. Trauma, hemorrhage and Arachnoid proliferation are the proposed mechanisms.  The primary pathology is a focal meningeal weakness resulting in dilatation of nerve root sleeves due to Csf pulsation and its hydrostatic pressure.
These are the leave alone lesions as they are often asymptomatic and detected incidentally. Usually associated with no neurological deficit, if any, may not correspond to cyst clinically.

Reference:  Multiple spinal nerve root cysts: Alparslan ~ENEL M.D. Orner Liitfi iyiGUN M.D. Zeki ~EKERCiM.D . Fahrettin ; Turkish Neurosurgery 2 : 41-43 1991