18 Posterior Cervical Foraminotomy/Discectomy

Luca Papavero

Summary

Posterior cervical foraminotomy (PCFo) is a clinically effective, cost effective, motion preserving, and time-proven surgical treatment for intraforaminal disc herniation and narrow root canal. In the past, the main disadvantage of the technique was the burdening postoperative neck pain due to the extensive subperiosteal dissection of the neck muscles from the midline. Nowadays, the blunt transmuscular approach has been borrowed from endoscopy and blended with the microsurgical/ microendoscopic technique through a tubular retractor. This development, described here, has significantly reduced the surgical traumatization while keeping all the advantages of PCFo unchanged.

In the daily practice, the average cost of an ACDF is 89% more than a PCFo. Provided a comparable patient outcome for either procedure, from a health care economics standpoint, a minimally invasive PCFo (mi-PCFo) should be considered in the treatment of cervical radiculopathy.1

Both the ventral and dorsal approaches offer certain advantages and disadvantages.

PCFo is a motion-preserving procedure that has been found to relieve symptoms due to foraminal soft disc fragment, bony spur, or synovial cyst in roughly 90% of patients.^2,3,4 It avoids the complications associated with anterior approaches such as dysphagia, hoarseness, and adjacent segment disease. Furthermore, fusion-threatening smoking, short-neck, location of pathology below C7 or above C3 are less burdening risk factors in the posterior than in the anterior route. However, one of the drawbacks of conventionally performed PCFo is significant subperiosteal muscle dissection and retraction to expose the lamino–facet junction, which may result in postoperative neck pain, muscle spasm, and malalignment of the spine.⁵ Recently, minimally invasive approaches for PCFo have been introduced to reduce the problems related to extensive soft-tissue dissection.^5,6 mi-PCFo is intended as a microsurgical procedure from skin to skin via a small paramedian incision, comprehensive of a blunt muscle-splitting approach with placement of a tubular or a miniaturized speculum retractor and decompression of the foraminal root Video 18.1.

18.2 Patient Selection: Indications, Contraindications

Indications:

•Intraforaminal soft disc herniations, provided that ≥ 2/3 of their mass is lateral to the dural sac (Fig. 18.1a–d).

•Bony narrowing of the root canal (Fig. 18.1e, f).

Relative indications:

•Paramedian disc herniations with a prevalent intraforaminal component which is clinically relevant.

•Intraforaminal synovial cysts and tumors.

•Increased risk factors for anterior surgery: professional singer, smoking, extensive scarring post thyroid surgery, location of pathology caudal to C7 and cranial to C3 in short neck.

Contraindications:

•Kyphotic malalignment or instability of the index level.

•Anomalous course of vertebral artery at the target level.

•Ossification of the posterior longitudinal ligament.

Relative contraindications:

•Recurrent disc and bilateral pathology.

For the well-selected patient, this operation can be extremely satisfying especially since the alternative involves anterior surgery and permanent implants. After the keyhole drilling has been performed, the editors find it helpful to identify next the medial border of the pedicles above and below, as they will define the foramen and the exiting nerve root in between. Be aware that sometimes there may be two nerve roots, a sensory and a motor branch in separate dural sleeves. This is an excellent description by one of the masters in the field.

18.3 Preoperative Planning

Preoperative planning includes:

•Preoperative imaging of the C-spine should answer the following questions:

○Biplanar X-ray with additional flexion/extension: spontaneous fusion of the target level? Labeling of the target level feasible in the operating room (OR; shoulder blade artifact C7-T1)?

○Computed tomography (CT) scan: calcified disc herniation? Additional bony narrowing of the root canal?

○Magnetic resonance imaging (MRI): relationship between the space-occupying lesion and the neural structures? Location of the vertebral artery at the target level?

18.4 Patient Positioning and Labeling of the Disc Space

After having performed the dorsolateral foraminotomy over years with the patient in sitting or in prone position, since two decades we favor the so-called Concorde positioning. It consists a reverse Trendelenburg which offers the advantage of a decreased epidural venous congestion but avoids the need of cardiac catheter to prevent air embolism (Fig. 18.2). Nowadays, the sitting position is an option for very obese patients or those affected by ventilatory disturbances.

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IV MISS Techniques Mini-Open Pedicle Subtraction Osteotomy for Deformity Correction Cervical Three-Dimensional Navigation to Facilitate Minimally Invasive Spine Surgery Far-Lateral Lumbar Discectomies Posterior Cervical Facet Cages DTRAX MIS-TLIF with Total Navigation and Expandable Interbody Cages

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