Patient Positioning

Francesco Ruggieri, Tommaso Zoerle, Filippo Gagliardi, Pietro Mortini, and Luigi Beretta

5.1 Introduction

Patient positioning for intracranial neurosurgical procedures represents a critical point for both the surgeon and the anesthesiologist. Some positions of the body for an extended period of time portend many intracranial, cardiovascular, or respiratory consequences that are often not well tolerated in some categories of patients. Hence a preoperative evaluation is mandatory to define any possible patient’s limitation to postural and positional changes that may be required to obtain a satisfactory surgical access.

Adverse events are mainly related to peripheral nerve injury and pressure sources that must be prevented by using padding of critical areas. Positioning the head to avoid excessive rotation and flexion/extension helps to prevent neuro-vascular complications due to reduced arterial flow to the brain or reduced venous return that causes further increase in intracranial pressure due to venous engorgement at the neck level. Injuries of the eyes include corneal lesions and ischemic optic neuropathy, which is mostly seen in the prone position.

Here we describe how to perform patient positioning for intracranial surgery minimizing adverse events.

5.2 General Principles

• Any possible limitation to postural and positional changes should be assessed preoperatively.

• Principal positions for intracranial surgery include

◦ Supine

◦ Lateral

◦ Prone

◦ Sitting

• The last two may cause major physiological cardiovascular and respiratory changes.

• Positioning is performed after induction of general anesthesia and placement of monitoring systems. Endotracheal tube and vascular access must be secured carefully because they can be displaced during positioning maneuvers (Fig. 5.1).

• Head may be positioned on a horseshoe head holder or pins fixation to the skull (Mayfield frame). Pins application is a high pain stimulus, so an adequate anesthesia plan must be provided in order to blunt a cardiovascular response and accidental patient movements causing skin laceration and even spinal injuries.

• Padding is pivotal for prevention of pressure sores and peripheral nerve injury. Eyes protection is mandatory to prevent corneal lesions (Fig. 5.1).

• Intermittent pneumatic sequential compression devices are necessary both to help reduce blood pooling in the legs and to prevent deep venous thrombosis (Fig. 5.2).

• Serum creatine phosphokinase elevation is often observed after prolonged surgery.

5.3 Supine Decubitus

Supine decubitus is the most frequently used position in Neurosurgery. It is advised in case of pathology of the anterior skull base and frontal/parietal/temporal convexity, as well as endoscopic endonasal and intraventricular procedures. According to the disease, the head can be placed either in neutral position or slightly rotated toward the controlateral side. The neck might be either extended or flexed based on the selected approach.

• The supine position is easy and safe with minimal cardiovascular effect.

Fig. 5.1 Supine decubitus: head.
Abbreviations: EP = eye protection; ET = endotracheal tube; NGT = nasogastric tube.

Fig. 5.2 Supine decubitus: legs.
Abbreviations: HP = heel pad; IPSC = intermittent pneumatic sequential compression devices.

Fig. 5.3 Supine position.
Abbreviations: EP = elbow pad; KP = knee pad.

• Slight head elevation improves cerebral venous outflow from the brain.

• A more physiological positioning of the lumbar spine, hips, and knees is achieved with the “lawn chair” position. It is a modification of the classical supine position with 15° angulation at the trunk and knees flexion. A roll is placed under the knees to keep them flexed and improve venous return (Fig. 5.3).

• Excessive neck flexion might result in tongue and pharyngeal edema. Thyromental distance must be kept greater than 3-4 cm (Fig. 5.4).

• Head rotation more than 45° and excessive neck extension/flexion could decrease flow into carotid and vertebral arteries and might give subsequent spinal or cerebral ischemia. If head rotation more than 45° is required, a roll should be placed under the contralateral shoulder (Fig. 5.5).

• Arms should be kept alternatively adducted or abducted less than 90°, to minimize brachial plexus injury. Excessive downward traction of the shoulders must be avoided (Fig. 5.6).

• The hands and forearms should be kept supinated or in neutral position, to reduce external pressure on the spinal groove of the humerus and ulnar nerve. Elbows and heels must be protected with pads (Fig. 5.6).