Missing disc fragment: A rare surgical experience
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A 72-year-old male patient presented with a history of the left buttock pain radiating to the left lower limb for the past 6 months, which aggravated over the past 2 days. On examination, the patient had no nerve root tension signs, and the bilateral straight leg raising test was negative. Extensor hallucis longus (EHL) and plantar flexion were Grade 3 power by Medical Research Council (MRC) grading on the left side. The patient also reported sensory deficit to both crude and fine touch over L5 and S1 dermatome in the left lower limb. There were no bowel or bladder symptoms. The patient was evaluated by MRI examination that revealed total of six lumbar vertebrae and a prolapsed intervertebral disc between L5 and L6 vertebra with left side lateral recess and foraminal stenosis and a possible posterior epidural migration of the disc fragment.

The patient was advised urgent surgical decompression by L5 and L6 laminotomy and microdiscectomy in view of neurological deterioration. Routine surgical steps for microdiscectomy were followed after confirmation of the level. L5 laminotomy was performed. The disc space was explored after securing the shoulder of the exiting nerve root. To surprise, the extruded disc fragment was not seen, and both the exiting and traversing nerve roots were absolutely free of any compression/tension with adequate mobility. Surgeons looked both at the level as well as above and below the L5–L6 disc level to find out the missing disc material. MRI was repeatedly checked and compared with X-ray images to ascertain the level of discectomy. Intraoperative C-arm images were taken to reconfirm the level of discectomy. The suction fluid was filtered through a surgical mop used as a sieve, and the material collected was sent for histopathological study. The roots and epidural space anteriorly were checked again with sweeping movements using Watson Cheyne retractor and nerve hook retractor under direct vision. After repeated confirmation, the incision was closed in layers. Postoperatively, the patient had relief from radicular pain (postoperative VAS for back and leg pain 3/10), and the motor power was improved (Grade 4/5 MRC). The biopsy report confirmed the material filtered was intervertebral disc material.

This case suggests that search for the missing fragment in a step-wise manner at the suspected locations improves the chance of detecting the missing disc material. Smaller the size of the fragment, extra care needs to be taken during the procedure as smaller fragments, especially when in the posterior epidural space is easily sucked into the suction apparatus while performing the routine surgical procedure or during sudden excessive bleeding while trying to clear the surgical field.

Source: http://www.asianjns.org/article.asp?issn=1793-5482;year=2020;volume=15;issue=3;spage=674;epage=677;aulast=Mallepally