As surgeons have developed familiarity with minimally invasive lateral approaches, a greater variety of spinal pathology is now being addressed. Initial indications for the use of a lateral retroperitoneal corridor traversing the psoas were limited. Only patients with lumbago associated with degenerative disc disease without evidence of severe central stenosis were considered candidates for this technique [1]. Any evidence of central stenosis, moderate spondylolisthesis, or significant rotatory scoliosis eliminated the patient for consideration of this approach. Advancements in instrumentation and expertise in the anatomic nuances of the lateral spine have increased the indications to utilize this approach. In addition to degenerative disc disease, a number of other indications are now accepted with lateral techniques, including moderate spinal stenosis especially foraminal stenosis, degenerative scoliosis, nonunion, trauma, infection, and low-grade spondylolisthesis [2]. Contraindications to performing laterally based surgery on the thoracolumbar spine include severe stenosis, aberrant vascular anatomy, high-grade spondylolisthesis, previous retroperitoneal surgery, and severely collapsed disc spaces and ankylosis of the facet joints at the target levels. The initial evaluation of patients being considered for lateral spine surgery begins with a thorough understanding of the approach itself, which will be discussed in detail in section II of this book. Lateral decubitus positioning, neuromonitoring, fluoroscopy, and soft-tissue management are all essential to a successful outcome using this technique.

Like any patient being considered for spine surgery, the initial workup begins with a thorough history to ensure the appropriateness for surgery and failure of conservative measures. Proper questioning of the patients can yield greater diagnostic value in ascertaining spinal pathology [3]. In addition to ascertaining the patient’s pain and neurologic symptoms pertaining to the spinal pathology in question during the history, particular attention must be given to possible characteristics that make them poor candidates for the lateral approach. For example, placement in the lateral decubitus position with the operative table jack-knifed may not be well tolerated by morbidly obese patients or those having undergone complicated hip or pelvic surgery. Certain demyelinating diseases, neuropathies, or myopathies may make utilization and interpretation of electromyography (EMG) difficult, thus placing the lumbar plexus more at risk during the dilation through the psoas. Spinal pathology at the L5–S1 level or cephalad to the thoracolumbar junction makes the approach more technically challenging due to the interference from the iliac crest and thoracic cage. Previous retroperitoneal surgery for renal disease or abdominal pathology may produce abundant scar tissue, making safe dissection to access the disc space difficult.

Attention to the details that put the patient at greater risk for nonunion or complications [4] should also be addressed during the history taking, such as tobacco use, uncontrolled diabetes, and osteopenia. Knowledge of patient medication allergies can eliminate the possibility of anaphylaxis, particularly in regards to perioperative antibiotics. Patient medications must be reviewed, with particular attention given to anticoagulants, antihypertensives, and diabetic medications and other medications that may contribute to osteoporosis.