Introduction

Despite a paucity of studies examining the mechanical compression of nerve roots in lumbar foraminal spinal stenosis (LFSS), it has been assumed that LFSS results in damage to microvascular structures and continuous compression of nerve roots, subsequently causing ischemia, edema, demyelination, and C-fiber hyperactivation [1, 2]. One hypothesis of the physiopathology in LFSS is that numerous lumbar foraminal ligaments cause low back pain and radiculopathy [3, 4]. Lumbar foraminal ligaments fix the lumbosacral spinal nerves to the intervertebral foramen and protect the nerve and blood vessels from being damaged. However, if abnormal adhesion or too many foraminal ligaments exist, they may result in pain through compression of the nerve root [5]. To achieve effective decompression of LFSS by resecting foraminal ligaments, and to facilitate the spread of medication around the target nerve, specially designed instruments for percutaneous lumbar extraforaminotomy (PLEF) was invented to allow a minimally invasive procedure.

Anatomy

The boundaries of the foramen contain two mobile joints – intervertebral disc (IVD) and zygapophyseal joints. The boundaries are:

• Roof: Inferior vertebral notch of the pedicle of the superior vertebra, ligamentum flavum at its outer free edge
  
• Floor: Superior vertebral notch of the pedicle of the inferior vertebra, posterosuperior margin of the inferior vertebral body
  
• Anterior wall: Posterior aspect of the adjacent vertebral bodies, the IVD, lateral expansion of the posterior longitudinal ligament, anterior longitudinal venous sinus
  
• Posterior wall: Posteriorly bounded by the superior articular process (SAP) and inferior articular process (IAP) of the facet joint at the same level as the foramen, lateral prolongation of the ligamentum flavum
  
• Medial wall: Dural sleeve
  
• Lateral wall: Fascial sheet and overlying psoas muscle.

Structures in the intervertebral foramen are:

• Spinal nerves (combined ventral and dorsal root in the root sheath)
  
• Dural root sleeve, which becomes continuous with the epineurum of the spinal nerve at the distal end of the foramen
  
• Lymphatic channels
  
• Spinal branch of a segmental artery, which, after entering the foramen, divides into three branches to supply the posterior arch, neural, and intracanal structures and posterior part of the vertebral bodies
  
• Communicating veins between internal and external vertebral venous plexuses
  
• Two to four recurrent meningeal (sinuvertebral) nerves
  
• Adipose tissue surrounding all the structures
  
• Ligaments in the neural foramen.

Lumbar foraminal ligaments are composed of the following ligaments [6–8] (Figure 65.1):

• Superior corporotransverse
  
• Inferior corporotransverse
  
• Superior transforaminal
  
• Middle transforaminal
  
• Inferior transforaminal.

Indications

• Lumbar radicular pain with or without low back pain
  
• Herniated nucleus pulposus
  
• Foraminal stenosis with or without central stenosis
  
• Perineural fibrosis
  
• Facet arthritis
  
• Hypertrophy of the ligamentum flavum
  
• Previous failure of conservative management (exercise therapy, physical therapy, analgesic medication, lumbar transforaminal epidural steroid injection, percutaneous epidural adhesiolysis etc.).

Contraindications

• Local or systemic infection
  
• Uncorrected coagulopathy
  
• Allergies to local anesthetics or contrast dyes
  
• Spondylolisthesis (relative)
  
• Severe degenerative change (relative)
  
• Patient refusal.

Technique

Percutaneous Extraforaminotomy (PLEF) provides advantages as a Minimally Invasive Spine Technique:

• Soft-tissue impingment is common
  
• Ligamentum flavum hypertrophy
  
• Provides access to the epidural space, posterior, and anterior canal
  
• It is a safe surgery under X-ray imaging
  
• Complications in experienced hands are extremely rare.

There are two specially designed instruments to implement PLEF.

1) Instrument consisting of (Figures 65.2 and 65.3):

• 16G Tuohy needle
  
• 14G trocar
  
• Cannula
  
• End mill
  
• Curette
  
• Catheter.

After 8–10 ml of 0.5% lidocaine was administered at the intended needle entry tract, a 15 cm, 16G Tuohy needle is inserted under anteroposterior fluoroscopic guidance. In the lateral fluoroscopic view, the needle tip is advanced until it is located at the posterior part of the borderline between the IAP and SAP. An epidurogram is then obtained after injection of 5 ml contrast to confirm that the needle is placed in the epidural space and to avoid intravascular or subarachnoid needle placement. Then, the Tuohy needle is withdrawn slightly to the level of the facet joint capsule. Subsequently, a trocar is inserted adjacent to the Tuohy needle and the Touhy needle is removed. Next, a cannula is inserted through the trocar to guide an end mill, which ultimately replaces the trocar. Finally, the end mill is placed within the epidural space in the intervertebral foramen. In the next step, the end mill is removed and a curette is introduced through the cannula while maintaining the bevel of the curette facing to the ventral side to avoid any neurovascular injury (Figure 65.4a–d).

2) Instrument consisting of ( Figure 65.6):

• Guidewire with a less than 1-mm diameter
  
• Dilator with a 2-mm diameter
  
• Working cannula (inner/outer diameter: 3 mm/3.5 mm)
  
• Working drill with a blunt-shaped tip and a protection shield.

Related posts:

Complications of Opiate Therapy Complications of Obturator Nerve Block Complications of Cervical Discography Complications of Intradiscal Therapeutic Procedures Complications of Percutaneous Cordotomy Complications of Stellate Ganglion Block (SGB)