49th Annual Regional Anesthesiology and Acute Pain Medicine Meeting

Case Report

Recovery of Ankle Dorsiflexion Weakness Following unilateral MILD ® Procedure in a Patient with Severe Spinal Stenosis.

Background

Lumbar spinal stenosis (LSS) is a spinal canal narrowing in one or multiple segments due to a herniated disc, ligamentum flavum thickening, facet arthropathy, or a combination of such degenerative change
Although there is no consensus on the definition of lumbar spinal stenosis, an anteroposterior spinal canal diameter of less than 10mm is frequently used to diagnose absolute or severe LSS
LSS is associated with severe disability in adults over 65 and is the most common cause of spinal surgery in this population.
Conservative treatment of lumbar spinal stenosis involves progressing from physical therapy (PT), analgesics, and NSAIDs to procedures such as an epidural steroid injection.
In cases of instability (spondylolisthesis), or failure of conservative management, classic surgical correction with laminectomy or, in some cases, laminectomy and fusion would be considered.
In the past 10 years, several minimally invasive interventions have become available to treat spinal stenosis, including the MILD® procedure (Minimally Invasive Lumbar Decompression

Case

70-year-old woman with a history of prediabetes, osteopenia, and depression who reported 10 months of tripping and falls and developed unsteady gait and standing difficulty. She subsequently developed lumbar pain radiating down the left lateral leg with tingling in both shins
Patient was admitted and spine decompression was recommended but patient deferred.
Lumbar MRI revealed severe L4-5 and severe L2 central spinal stenosis and severe L4-5 foraminal stenosis, ligamentum flavum thickening of 5.2mm
Laboratory work-up was negative and patient was discharged with an AFO and PT.
She presented to our outpatient spine center four months after developing a left foot drop with continued pain in the lumbar spine with neurogenic claudication in the left distal leg, triggered by standing and walking compatible with L4-5 spinal stenosis
On physical exam, patient had left ankle dorsiflexion weakness (1/5) and left EHL weakness (2/5). Right leg strength was normal in all myotomes. Agreed to Left L4-L5 MILD Decompression. Post-op follow up at 2, 6, and 12 weeks.
2-week follow-up:no longer required an AFO to ambulate. Her neurogenic claudication had improved, and she doubled her standing and walking time to 20 minutes.
6-week follow-up: walking and standing tolerance improved to 40 minutes, and she had complete resolution of her left ankle dorsiflexion weakness.
12-week follow-up: in conjunction with PT, she reported a near symptom-free state. She had normal left ankle dorsiflexion and EHL strength and could tolerate 40 minutes of walking and standing.
Ten months after the MILD® procedure: she had an EMG at an outside facility, which showed normal motor studies, normal H-reflex, and +1 chronic small amplitude fibrillation potentials in her left tibialis anterior with mild chronic reinnervation features

Discussion

Lower extremity weakness, including foot drop, requires expedited imaging, PT, a course of oral steroids, an epidural steroid administration, and in persistent cases, decompression.
Traditional decompression options are open hemilaminectomy, full laminectomy, or combination laminectomy and fusion when instability exists.
MILD® is a low-risk procedure with a safety profile similar to epidural steroid injections. Studies show statistically significant improvement in VAS scores , function and 74% patient satisfaction in those undergoing Mild procedure for spinal stenosis
In a five-year durability study, 88% of patients undergoing MILD® did not require open surgical intervention
In addition to this reported case, we treated two other patients with focal foot drops, both of whom achieved full-strength recovery (one had thickening of ligamentum flavum and a synovial cyst which was decompressed with MILD®
Based on the impressive motor recovery achieved after the MILD® procedure in this case, we propose an early adoption of MILD® in the treatment algorithm of spinal stenosis with focal weakness

Conclusion

In carefully selected patients, early introduction of the MILD® procedure in the treatment algorithm of spinal stenosis with focal dorsiflexion weakness has the potential for complete motor strength recovery alongside previously established statistically significant improvement in neurogenic claudication, disability, and quality of life metrics

References

Kaye AD, Edinoff AN, Temple SN, Kaye AJ, Chami AA, Shah RJ, Dixon BM, Alvarado MA, Cornett EM, Viswanath O, Urits I, Calodney AK. A Comprehensive Review of Novel Interventional Techniques for Chronic Pain: Spinal Stenosis and Degenerative Disc Disease-MILD Percutaneous Image Guided Lumbar Decompression, Vertiflex Interspinous Spacer, MinuteMan G3 Interspinous-Interlaminar Fusion. Adv Ther. 2021 Sep;38(9):4628-4645. doi: 10.1007/s12325-021-01875-8. Epub 2021 Aug 14. PMID: 34398386
Wu L, Cruz R. Lumbar Spinal Stenosis. [Updated 2021 Aug 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan.
VAS, Z. (2010). MiDAS I (mild® Decompression Alternative to Open Surgery): A preliminary report of a prospective, multi-center clinical study. Pain Physician, 13, 369-378.
Staats, P. S., Chafin, T. B., Golovac, S., Kim, C. K., Li, S., Richardson, W. B., ... & Benyamin, R. M. (2018). Long- term safety and efficacy of minimally invasive lumbar decompression procedure for the treatment of lumbar spinal stenosis with neurogenic claudication: 2-year results of MiDAS ENCORE. Regional Anesthesia & Pain Medicine, 43(7), 789-794.

49th Annual Regional Anesthesiology and Acute Pain Medicine Meeting

RECOVERY OF ANKLE DORSIFLEXION STRENGTH FOLLOWING MILD ® PROCEDURE IN A PATIENT WITH SEVERE SPINALSTENOSIS. A CASE REPORT.

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