A 75-year-old right-handed female with the medical history of generalized anxiety disorder and major depressive disorder with a history of SI has been treated with thioridazine and citalopram from 1980 till 2010. Around 2008 at the age of 67, she developed orolingual dyskinesia: "difficulty with her tongue thrusting out of her mouth, causing the tongue to be sore and lips to be chapped, and annoying her." Her treatment and symptom timeline are summarized in [Figure 1]. Benztropine and oral lidocaine did not alleviate the movements and thioridazine was discontinued. In January of 2011, quetiapine 50 mg was started. This did not control her oTD, and in addition, she developed an urge to chew (was chewing on carrots or almonds to relieve the urge) and her husband had noticed that she was moving her legs and rocking her body. The patient herself was unaware of these movements. Subsequently in June 2011, she was started on TBZ 12.5 mg bid which successfully relieved her oTD. In December 2011, she was hospitalized for worsening depression, lost her job, and underwent a 13-treatment course of electroconvulsive treatment (ECT). At that time, she was taking 12.5 mg TBZ 3 times daily along with fluoxetine 50 mg, quetiapine 200 mg, and trazodone 100 mg nightly. Her oTD remained under control with TBZ 12.5 mg bid. She had two falls in 2012. By July of 2013, she developed intermittent right foot resting tremor and postural and kinetic hand tremors that were making it difficult for her to eat soup with a spoon, eat with a fork, and write. Propranolol at 10 mg bid was started with possible benefit. When first seen by us in January of 2015, she had mild oral TD, bilateral resting and postural hand tremors, and moderate right leg resting tremor. There was mild to moderate bradykinesia in both lower extremities and she had mildly Parkinsonian gait [Video 1]. With oTD controlled, tremors were the most bothersome symptom. To help with it, the following medications were tried without a success: propranolol up to 20 mg tid, Amantadine, Sinemet, Pramipexole, and Primidone. Propranolol was stopped due to worsened depression. Her tremors had transiently yet significantly worsened with increased TBZ dose to 25 mg tid. It seemed that tremors were aggravated by TBZ and two trials TBZ discontinuation were carried out, one 3 weeks in duration in 2015 and one of 1 week in duration in 2016 (she was unable to stay longer off TBZ due to recurrence of oTD). However, discontinuation of TBZ did not alleviate the tremors. Lowering quetiapine from 200 to 100 mg and tapering off fluoxetine did not improve tremors, either. Unfortunately, overtime both the tremors and Parkinsonism worsened to the point that she was unable to have meals at the table due to violent proximal leg tremor, nor was she able to feed herself. Her balance continued to worsen and in 2015 she had a fall and broke her hip.
A possibility of therapeutic DBS surgery was discussed and the patient was eager to get the treatment. Her dopamine transporter (DAT) scan showed normal DAT in basal ganglia. One possibility for this patient was to target the GPi with the hopes of alleviating her oTD and discontinuing treatment with TBZ. However, due to the two trials of TBZ discontinuation not alleviating the tremors, this was considered too risky. Therefore, a decision was made to target the STN with the goal of alleviating her main complaint which was resting leg and hand tremor, as well as bradykinesia and rigidity.
In January 2017, she underwent left STN implantation with Medtronic DBS system, with initial near-complete resolution of tremors. In September 2017, she underwent right STN implantation with similar improvement, however with the side effect of marked hypophonia and mild cognitive impact [Video 2]. The coordinates used for both implants were 12 mm lateral, 4 mm inferior, and 4 mm posterior to the midcommissural point. She currently requires stimulation of 3.4 V on the left and 4.2 V on the right for symptomatic relief. Two years after implantation, her leg tremors are not at all bothersome and she is able to feed herself. She feels that she is almost "perfect," but she still has a fear of falling and uses a walker for ambulation. Regardless, she is able to participate in weekly ballet classes and is exercising 2 days/week. She continued to need TBZ 25 mg bid but in the wake of worsening Parkinsonism (small handwriting), she was recently switched to Valbenazine 40 mg daily.