Localization of the Anterior and Posterior Commissures for Deep Brain Stimulation Using Only Stereotactic Computed Tomography Scan

Deep brain stimulation (DBS) requires accurate presurgical targeting, conventionally performed using magnetic resonance imaging (MRI) to identify stereotactic landmarks based on the anterior commissure–posterior commissure (AC–PC) line. However, MRI may be contraindicated in patients with retained metallic foreign bodies, making target localization challenging when relying on computed tomography (CT) alone. The tuberculum sellae–occipital protuberance (TS–OP) line has been proposed as an alternative anatomical reference to approximate the AC–PC line and facilitate CT-based targeting. A 62-year-old male police officer presented with a 7-year history of resting tremor and bradykinesia and was diagnosed with Parkinson's disease. He was initially managed with levodopa-carbidopa 300 mg/d, but despite medical therapy, his symptoms progressively worsened, with “on” periods reduced to only 2.5 to 3 hours daily, prompting referral for DBS evaluation. Baseline assessment showed a Hoehn and Yahr stage III and a Unified Parkinson's Disease Rating Scale Part III score of 51 (right: 20, left: 14). Surgical planning was complicated by a history of gunshot injury 36 years prior, resulting in two retained metallic bullets in the neck and trunk, precluding MRI acquisition. CT-based stereotactic planning was therefore performed using the TS–OP line as a surrogate to estimate the AC–PC line and guide target localization. This case demonstrates the feasibility of CT-only stereotactic planning for DBS in patients with contraindications to MRI. The use of the TS–OP line as an anatomical surrogate for the AC–PC line may provide a practical and reliable alternative for target localization in resource-limited or MRI-ineligible cases.