This case involves a middle-aged man in North Carolina who underwent a number of spinal surgeries in order to treat chronic spondylolysis. Following a spinal fixation procedure, however, the patient woke up with left-sided foot drop. Imaging studies revealed the presence of a pedicle screw that may have been impinging on the spinal cord, however the surgeon initially thought the new symptoms were related to excessive manipulation during the procedure. As a result of this assessment, the patient was placed on IV steroids and was treated conservatively. Over the next few weeks, however, the man continued to suffer from foot drop. Eventually, he was taken back for a revision and removal of the pedicle screw. Nevertheless, the man continued to suffer from foot drop with no improvement in his symptoms.
Question(s) For Expert Witness
- 1. How frequently do you perform similar surgeries?
- 2. In a patient with a new foot drop after a lumbar decompression and fusion, what is the standard workup?
- 3. If a malpositioned pedicle screw was thought to be the cause of the new neurologic deficits, how long would you wait to take the patient back to the operating room for a revision surgery?
Expert Witness Response E-102150
I perform similar surgeries at least once a week. The standard workup is an MRI to look for nerve compression, but you have to have the ability to perform metal artifact reduction MRI sequence or through-plane artifact reduction MRI sequence (MAVRIC or SEMAC) to reduce the metal artifact that hinders the visualization of the neural elements. If unable to perform this type MRI imaging then CT myelogram is the best alternative. If imaging reveals mechanical compression of the nerve then immediate surgical decompression should be performed with neuro-monitoring. If imaging is negative then the surgical exploration of the nerve should be performed immediately with neuro-monitoring and if no visible compression or injury to the nerve is found then the surgeon should restore the L5-S1 spondylolisthesis to reduce the stretching of the L5 nerve root. If a malpositioned pedicle screw was thought to be the cause of the new neurologic deficits, the patient should be back to the operating room for revision surgery immediately to relieve the compression and give the nerve the best chance for any recovery. Foot drop in this type of surgery can arise from many reasons but most commonly from the reduction of the spondylolisthesis of L5 over S1 that causes the stretching of the L5 nerve root. It is a risk that the patient should be made aware of and documented in the consent prior to surgery. The possibility of mechanical nerve compression by a pedicle screw or residual bone spurs is also common. In order to avoid this type of injury, neuro-monitoring should be used to monitor the nerve integrity throughout the duration of the case.