background(mild) is a percutaneous procedure for symptomatic lumbar spinal stenosis (LSS) treatment where ligamentum fl avum hypertrophy (LFH) is a contributing factor. LSS is prevalent in the elderly and is most often associated with complaints of neurogenic claudication. Historically, patients failing conservative therapy resorted to epidural steroid injection (ESI) to relieve pain. Generally, ESI provides short term pain relief, followed by recurrent symptoms that require repeated ESI until such time as open decompression surgery is medically indicated. The mild procedure offers the properly selected patient a safe, lasting, minimally invasive option for the early treatment of neurogenic claudication associated with LSS. Safety and effi cacy of the mild procedure have been previously reported.

objectiveTo describe proper patient selection used to obtain optimal results with the mild procedure.

methodsPatients expected to benefi t from the mild procedure are selected based on clinical presence of symptomatic lumbar spinal stenosis. They complain of intermittent pain, numbness/tingling, and/or heaviness in the leg which is differentiated from steady radicular pain. These neurogenic claudication complaints are activity-induced by prolonged erect standing or walking and are relieved by fl exion (bending or sitting), unlike vascular claudication in which stopping as opposed to fl exion, provides relief. Adequate imaging studies are used to verify hypertrophied ligamentum fl avum (> 2. 5 mm thickness) and lumbar canal stenosis.

resultsThe majority (~90%) of LFH fi ndings were bilateral and were most often (~60%) multi-level. Excellent long-term patient satisfaction and outcomes including mean pain reduction >40% and mobility improvement of > 25% were obtained, thus demonstrating the value of proper diagnosis and patient selection. In addition, > 800 mild procedures were safely performed in clinical trials with similar outcomes and no reported serious adverse effects such as hematoma, blood loss requiring transfusion, nerve root damage or dural tear. With over 15,000 commercial (non-study) procedures performed to date, three adverse events have been reported, yielding an overall rate of < 0.02%.

conclusionsThe mild procedure is a safe, effective, durable method for the treatment of LSS. Adequate diagnosis and patient selection make mild an excellent treatment option for patients suffering with neurogenic claudication.

keywordsLumbar spinal stenosis, decompression, mild, neurogenic claudication, ligamentum fl avum.

by: william o. witt, mdcardinal hill pain institute, lexington, kentucky

mild® percutaneous decompression: proper diagnosis/patient selection key to excellent results

Current LSS Treatment Options

Minimally Invasive• Low Complications• Low Biomechanical

Change

Invasive• High Complications• High Biomechanical

Change

Safety

EffectivenessPalliative Therapeutic

Conservative Therapy– Physical Therapy, Exercise

Radio Frequency Ablation

Interspinous Spacers

Laminotomy /Laminectomy

Fusion

When conservative therapies fail and decompression intervention is indicated,  make the appropriate choice. Epidural Steroid 

Injections

Neuromodulation

mild can be introduced early to treat Neurogenic Claudication pain, and Radicular Pain can still be managed with ESIs.

Managing LSS Patients’ Pain

Time

Pain Goal of Physician‐Keep Patient Below Pain Threshold

NeurogenicClaudication (NC)‐Pain increases over time and is unaffected by ESIs

Radicular Pain (RP)‐Managed by  ESIs

Differential Diagnosis (DDx) Relevance 

• Radicular pain and neurogenic claudication can both be found in LSS patients.

• Neurogenic claudication occurs in 94% (Hall) to 99% (Cavusoglu) of LSS patients.1,2

• ESIs work short‐term with radicular pain.• ESIs do not help with progressive neurogenic claudication. 

• mild effectively treats LSS patients’ neurogenic claudication. 

1Hall S, Bartleson JD, Onofrio BM, Baker HL, Okazaki H, O’Duffy JD. Lumbar spinal stenosis. Clinical features, diagnostic procedures, and results of surgical treatment in 68 patients. Ann Intern Med 1985;103(2):271‐5.2 Çavuşoğlu H, Kaya RA, Türkmenoglu ON, Tuncer C, Çolak I, Aydin Y. Midterm outcome after unilateral approach for bilateral decompression of lumbar spinal stenosis: 5‐year prospective study. Eur Spine J 2007;16(12):2133‐42.

Clinical Symptoms, Imaging, Choice

Focus on Symptoms

Validate DDx with MRI

Assess Treatment Options

– LSS Symptoms– Evidence of NC Symptoms– Note the DDx between Radicular Pain and Neurogenic Claudication

– Tx RP– Tx NC pain– Choose method of Tx

– Map pain pathways– Assess posterior pressure vs. other causes– Validate adequate tissue for posterior debulking of HLF

When the Choice ismild…      Clinical Study Results

Clinical Study Outcomes

Safety • No SAEs in over 400 study patients 

Significant Reduction in Pain at Year 1

• LSS with multiple causal factors in 100% of cases• 79% of LSS study patients achieved pain reduction:

– Mean Pain reduced by 53%– VAS mean Improvement 4.0 points

Significant Increase in Mobility at Year 1

• LSS with multiple causal factors in 100% of cases• The 79% of LSS patients who achieved VAS improvement also experienced:

– Mean Mobility increase of 34% – ODI Score mean improvement 16.6 points

Visual Confirmation of Stenosis

Confirm stenosed level(s), ligament hypertrophy and severity of other LSS causal factors.

LSS Treatment AlgorithmDifferential Diagnosis (DDx) Makes a Difference 

Differentiating symptoms of radicular pain and neurogenic claudication matters.

ESILSS 

Patient

Historical Treatment Algorithm

Radicular Pain = Temporary Relief, Repeat

Neurogenic Claudication = No Effect

ESILSS Patient

Current Treatment Algorithm

Radicular Pain = Temporary Relief, Repeat

Neurogenic Claudication = Long Term ReliefESIESI

Conclusions

• Differential diagnosis enables appropriate treatment choice in the LSS treatment algorithm.– mild percutaneous decompression treats neurogenic claudication.

– ESI treats radicular pain.

• Imaging studies confirm stenosed levels, presence of hypertrophic ligamentum flavum, and presence and extent of additional causal factors to aid in optimal treatment choice.

• Appropriately selected patients can achieve statistically significant and clinically relevant pain reduction and improved mobility with  mild percutaneous decompression.

• Lumbar Spinal Stenosis can be safely treated percutaneously.

Differentiating Pain: Neurogenic Claudication or Radicular?

Neurogenic claudication complaints are reduced by forward flexion, slowed gait, leaning onto objects (e.g., over a shopping cart) and limiting distance of ambulation. Downhill walking is worse than uphill.

Ask Your Patient: Neurogenic Claudication  Radicular Pain 

Pain when walking erect? Yes – relieved by flexion Yes – flexion  has no effect

Pain when standing erect? Yes – relieved by flexion Yes – flexion  has no effect

Pain when seated? No Yes – increased pain

Pain when bike riding? None or minimal Yes

Bilateral pain? Yes – most often No – primarily unilateral

Constant pain? No – mostly with activities Yes

Does sharp pain discourage standing up?

No Yes

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