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Complications of Interspinous Decompression

Sean Li MD

Jersey Shore University Medical Center, New Jersey, NJ, USA

Introduction

The diagnosis of symptomatic neurogenic claudication begins with clinical history and supporting physical exam findings. This is confirmed with radiographic evidence of mechanical narrowing of the affected lumbar segment(s). One must rule out other pathologies such as lumbar radiculopathy and pain generators such as degenerative facet joints. The detailed process of diagnosing neurogenic intermittent claudication (NIC) is beyond the scope of this chapter.

Anatomy Related with NIC

Symptomatic NIC results from the degenerative process of the spine that leads to narrowing of the spinal canal and eventual compression of nerve roots known as spinal stenosis [1]. This stenosis can occur in various locations including central canal, foraminal or lateral recess, leading to characteristic symptoms described as pain or discomfort that radiates to the buttocks, thighs or lower extremities with or without low back pain [2]. Patients may also report numbness, weakness, and muscle cramps in the lower extremities. The symptoms of neurogenic claudication often worsen with standing and walking and improve with sitting or forward flexion. This phenomenon is often known as the “shopping cart” sign.

Indications

For patients who have failed conservative medical management
For patients who have failed epidural steroid injection that are not surgical candidates
Indirect interspinous decompression offers a minimally invasive option for treatment of symptomatic spinal stenosis at L1–L5.

Contraindications

Allergy to titanium alloy
Anatomic limitations, for example, ankylosed adjacent spinous processes
Unstable spondylolisthesis
Moderate/severe spondylolisthesis grade II or beyond
Severe osteoporosis greater than T–2.5
Scoliosis, Cobb angle > 10 mm
Prior surgery at the affected levels
Body Mass Index (BMI) greater than 40.

Technique

Types of Devices

Currently, there are two Food and Drug Administration (FDA) approved interspinous/interlaminar process spacers: Coflex® (Deerfield, IL) and Superion® (Valencia, CA) devices. The Coflex device is implanted after surgical decompression of the canal, while the Superion is a “stand-alone” device not requiring surgical decompression [3]. Both of these interspinous process devices may be implanted at one or two adjacent lumbar levels. The X-STOP® (Medtronic, Minneapolis, MN) Interspinous Process Decompression (IPD) System received FDA premarket approval in 2005, however it was withdrawn from the US market in 2015. Recently, there have been several additional posterior interspinous decompression devices introduced to the market. The exact indications are unclear if they are to be used as stand-alone devices or combined with additional surgical instrumentation. These devices also lack long-term peer-reviewed clinical evidence.

Among the two interspinous decompression devices presented, the Superion device is the only stand-alone minimally invasive interspinous device within the scope of practice of an interventional pain physician. This is a fluoroscopically guided procedure performed under conscious sedation in an outpatient setting. Physicians are required to obtain specific didactic and hands-on training prior to obtaining certification and institutional credentials. The procedure utilizes a set of single-use instruments designed to deliver the implant (Figures 60.1 and 60.2). The procedure itself is divided into a series of ten steps starting with patient positioning, leading to serial dilation and placement of working canula, followed by reaming out the interspinous space allowing for proper measurement of desired spacer, and finally deployment of the device and surgical closure.