Delayed Onset Eye Opening Apraxia due to Progression of Brain Atrophy following Subthalamic Nucleus Deep Brain Stimulation: A Case Report

Abstract

Eye opening apraxia (EOA) has been described in literature as a complication of deep brain stimulation (DBS), especially after electrode implantation in the subthalamic nucleus (STN). EOA can be either worsened or alleviated by DBS depending on the etiology. Herein, we report a rare case where the progression of brain atrophy may have contributed to the delayed onset of EOA. The patient, a 73-year-old woman, had previously undergone bilateral STN-DBS for advanced Parkinson's disease (PD), which was performed by another DBS team, at the age of 68 years. She initially experienced a dramatic improvement in her motor symptoms, with no adverse events. However, she had difficulty in opening her right eye 3 years after the DBS surgery. Imaging studies showed that the brain atrophy had progressed over the past 5 years, and that the DBS electrodes were implanted through the far anterior entry points. We considered that the relative movement of the DBS might have been caused by the progression of the brain atrophy to the posterior limb of the internal capsule (IC) where the corticobulbar tract exists, and this was enhanced by the lower implantation angle. The present case illustrates the importance of the DBS insertion angle considering the a+ trophic effect and the follow-up imaging studies after DBS.

Keywords: adverse event; corticobulbar tract; deep brain stimulation; eye opening apraxia.

Fig. 1

Imaging studies of the patient. A and B. Skull X-ray images showing the intracranial electrodes with the far anterior entry points. C and D. T ₁ -weighted images with contrast for stereotactic planning at the age of 68 years. E and F. T ₁ -weighted images without contrast 5 years after DBS surgery. These MRI images show the atrophic change in the brain over a period of 5 years.

Fig. 2

Relationship between the implanted electrode and internal capsule. In this figure, the electrode is positioned at a 44° AC-PC angle, and the dotted line indicates DBS trajectory at a 65° AC-PC angle. The figure illustrates that the lower insertion angle may determine the distance between each DBS contact and internal capsule. Vim = ventral intermedius; Voa = ventralis oralis anterior; Vop = ventralis oralis posterior.