TEN QUESTIONS ON PERCUTANEOUS ENDOSCOPIC LUMBAR DISCECTOMY (PELD)
What is PELD?PELD is a technique where the lumbar disc is visualized through a 4mm endoscope directed from the flank through the intervertebral foramen.
What are the advantages of PELD?
There are many advantages with PELD. First and foremost the entire procedure is done under local anesthesia. The patient is completely awake and aware of his surroundings during the entire procedure. Since the procedure is done under local anesthesia the morbidity due to neurological complication is close to zero. The entire procedure of visualizing the disc and decompressing the exiting root is done through the endoscope. In all other endoscopic discectomy procedures the endoscope is used for assistance and technically there are not completely endoscopic procedures.
Is the procedure very expensive?
No procedure is inexpensive. One needs a dedicated PELD, a fluoroscopic equipment and a radio frequency lesion generator. Upto the point of introducing the scope into the disc space the procedure is done under fluoroscopy. Once the PELD is in position the procedure is under telescopic control.
How does this procedure differ from the classical approach to the disc disease? In the classical approach the disc space is reached from a posterior midline incision. The muscles are separated from the midline and underlying bone is exposed. Using a microscope some bone is drilled and the neural tissue is exposed. The neural tissue is retracted with instruments and the disc space is exposed. So many tissues have to be transgressed to reach the offending disc tissue. Since some much dissection is needed this procedure needs general anesthesia. In PELD the disc space is reached without any dissection. The procedure is done through a 7mm incision which need not be sutured at the end of the procedure.
How is PELD done?
The patient is made to lie down on his face and using a fluoroscope the point of entry is pre determined. The entry point is numbed with few mls of local anesthetic. A large bore needle is introduced from the flank into the disc concerned. The procedure is done under fluoroscopic control. Once the needle is in correct position, a guide is introduced into the disc space through the needle. The needle is then removed keeping the guide wire in place. The track is then dilated using a tapered dilator. A sheath is then threaded over the dilator under fluoroscopic guidance. The dilator is then removed and the f PELD is introduced. The entire procedure is done through a 7mm incision which need not be closed. The discectomy is done under telescopic control through the endoscope. The entire procedure lasts about 25 minutes and the patient can be sent home the same day.
How is it better than other procedures for the disc disease?
Classical approach to disc entails extensive dissection of the muscles and removal of bone and some midline ligaments. All these structures are very important in maintaining the spinal stability. So many patients end up with pain at the operation site post discectomy. Since the procedure is done under general anesthesia patient needs to stay in the hospital for longer duration. There will be some blood loss during the procedure. PELD entails no tissue dissection, no retraction of neural tissue, very minimal blood loss, shorter hospital stay and no neurological morbidity. Since the posterior elements are not disturbed there is no procedure related post op pain.
Can PELD be done under general anesthesia?
Yes. PELD can be done under general anesthesia. But it is not needed. The incidence of neurological complications will be more when PELD is done under general anesthesia. In local anesthesia the patient is awake and aware and the needle can be inserted with no fear of damaging any neural tissue. All the advantages of local anesthesia will be forfeited if the procedure is done general anesthesia.
What investigations need to be done before planning the patient for PELD? For a patient to under go PELD MRI of his or her lumbar spine is a must. MRI shows the annular tears better than any other investigations. The size of the foramen can also be measured and the exact relation of the disc to the exiting root can be made out. Rarely congenital anomalies like nerve root abnormalities are seen in mri where PELD is contraindicated.
Can any other procedures be done with PELD?
Yes. Using a PELD the foramen can be widened by reaming and by using lasers. One can do decompression an dstabilization in conditions like spondylolisthesis. This is called hybrid surgery and it is minimally invasive. Work is on to do liagamentous decompression in canal stenosis with out removing any bone. One can also do reduce the facetal hypertrophy using lasers through foraminiscopy. Research is being done to do a procedure called annuloplasty where the annular tears are repaired with out any disc removal.
Can PELD used in disc problems in the neck?
Disc problems in the neck can be addressed using an endoscope but he entry here is from front. The usage is limited in the sense the disc should be soft and swallowing movements may impede the surgeon. One may be forced to use general anesthesia in these circumstances and the very purpose of awake and aware surgery is defeated.