Prior to surgical positioning, neurophysiologic monitoring leads are placed. Somatosensory and motor evoked potentials are used to ensure neurologic safety. Appropriate and cord monitoring friendly anesthesia is used. For lateral extracavitary approach, the patient is typically positioned prone onto a radiolucent surgical (e.g., Jackson frame) table allowing for use of fluoroscopy. Alternatively, the patient can be positioned in an inclined lateral decubitus (60 degrees forward) with axillary roll placed under the dependent side. The patient’s abdomen is kept free hanging without pressure, to prevent venous congestion and intraoperative bleeding. The level of interest is then marked prior to sterile draping. Counting from a clear and known
anatomic landmark is essential to prevent wrong-level surgery. It is crucial to carefully examine the preoperative MRI and CT scans, correlate with the x-rays, and confirm the level of interest based on the established anatomic landmarks (e.g., counting from C2-down, or from the sacrum up). The surgical field is then draped in a sterile fashion, with wide margins including the lumbar and/or the cervical spine to allow for repeat vertebrae counting and pathology level confirmation. A K-wire is then used under fluoroscopy to mark the skin incision site. The K-wire is used to mark the disk space level with its corresponding endplates. The superior endplate of the vertebral body below the disk of interest is then marked along with the respective pedicle and transverse process (on the same side of the herniation). The skin incision site (vertical, ˜3 cm paramedian) is then localized under image guidance with the fluoroscopy beam adjusted to clearly visualize the disk space, the pedicle and transverse process of the vertebra below it, and the pars interarticularis of the vertebra above it. Local anesthetic (Marcaine with or without epinephrine) may be infiltrated along the surgical trajectory. The patient is secured to the bed using safety straps to allow for safe patient rotation.

A vertical paramedian skin incision is made followed by vertical fascia split overlying the lateral border of the rib heads above and below the level in question.¹⁰, ¹¹, ¹² The distance of the incision from the midline depends on the patient’s body habitus and on the location of the disk herniation. Foraminal disk herniation may not necessitate an excessive oblique working channel compared to the central large disk herniation with flattening and deformation of the spinal cord. Blunt finger dissection is carried feeling for the bony anatomy, followed by sequential tubular dilator placement under fluoroscopy. The tubular dilators are docked at the facet-transverse process junction caudal to the disk in question (e.g., dock on the facet joint of T10-T11 and the transverse process of T11, when aiming for T10-T11 diskectomy).