Initial programming of deep brain stimulation of hypothalamic/fornix for severe Alzheimer′s disease

Objective To explore the initial start-up programming and efficacy of deep brain electrical stimulation (DBS) of the hypothalamic fornix (HF) in the treatment of severe Alzheimer′s disease (AD). Methods A retrospective study was conducted on 9 patients with severe AD who underwent DBS-HF at Department of Neurosurgery, the First Medical Center of Chinese PLA General Hospital from June 2015 to September 2018. Postoperative cranial MRI was performed to determine the electrode position. Four weeks after operation, DBS device was turned on with initial programming set as unipolar stimulation with a frequency of 130 Hz, pulse width 90 μs and voltage of 3 V. The emotion, memory, calculation, language or communication and orientation of the patients were observed based on corresponding function of the brain area where the electrode contacts were located in order to determine the optimal contact and stimulating mode was thus maintained. Outpatient follow-up was conducted for all patients 3 months after the start-up. The follow-up included assessment of the patient′s emotion, memory, calculation, language, communication and orientation evaluated at initial programming. In addition, the patient′s sleep conditions and social skills were documented through consultation with the patient′s families. Results Nine patients were successfully operated. No perioperative complications such as intracerebral hemorrhage, abnormal electrode connection or wound infection occurred after operation. The electrodes of 9 patients were accurately implanted into the preset target position. At initial programming, there were no adverse effects reported including psychiatric and behavioral disorders, cardiovascular events and intolerance of stimulation. Among the 9 patients, memory was improved in 2 and mood was improved in 1. No symptom worsening was observed in the patient with severe psychiatric disorder who underwent bipolar stimulation through optimal contacts. Nine patients were followed up for 3 months. Among them, 7 had improved mood, 5 had improved memory, 7 had improved sleep, 6 had improved language ability, 3 had changed social intercourse, and 4 had changed orientation. However, there was no significant change in calculating power of 9 patients. Conclusions The preliminary results have suggest that the program-controlled startup scheme with functions of test, calculation, memory, emotion and physiology could be a way to ensure the efficacy of HF-DBS in the treatment of severe AD patients. Key words: Alzheimer′s disease; Deep brain stimulation; Fornix, brain; Treatment outcome; Programming