IONM in Spinal Surgery

Introduction

IONM is used in a variety of spinal surgeries to assess spinal cord and nerve root function.

Relevant clinical symptoms

1. Foot drop. Foot drop is an abnormality in gait that makes it difficult to lift the foot. Injury to the deep peroneal nerve is the most common cause of foot drop. The peroneal nerve is a branch of the sciatic nerve that exits at nerve roots L4-S2 and innervates the anterior and lateral compartments of the leg, including the tibialis anterior and other muscles that allow us to raise our foot from the ankle (dorsiflexion). Foot drop can also tighten the muscles that allow us to point our feet downward (plantar flexion). The plantar flexor muscles, such as the gastrocnemius and soleus, are innervated by tibial nerve.

2. Scoliosis. Scoliosis is a deformity in the vertical alignment of the spine. Scoliosis is defined as a lateral curvature of the spine that includes rotation of the vertebrae. The misalignment can be in the shape of a C or an S. Scoliosis is diagnosed when there is at least a 10 degree angle in the alignment of the vertebrae as viewed in the anterior-posterior plane. Scoliosis is broadly classified as congenital, neuromuscular, and idiopathic in origin. Physicians characterize the type of scoliosis using the Lenke classification system.