Both the staged bilateral STN DBS and the simultaneous bilateral procedure are effective and safe treatment options, but the staged bilateral procedure may be regarded as the preferred choice for the treatment of some patients.

Background: Speech disorders are among the most common adverse effects after subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson's disease (PD) patients. However, longitudinal speech changes after STN-DBS are not fully understood. Objective: We performed a two-year prospective study on PD patients who underwent STN-DBS and analyzed changes in speech function to clarify factors predicting for speech deterioration. Methods: Twenty-five PD patients were assessed before and up to two years after STN implantation. Speech function was evaluated in the on-stimulation condition and 30 min after stimulation cessation using auditory-perceptual assessment. Patients who experienced overall worsening in speech intelligibility or naturalness ≥1 point during follow-up were classified into a deteriorated group (n = 16), with the remaining subjects being classified into a stable group (n = 9). Cognitive and motor functions were also assessed. Results: The stable group had significantly better values of low volume, monoloudness, and asthenic voice subscores of the auditory-perceptual assessment in the on-stimulation condition compared with the off-stimulation condition. Imprecise consonants, excess loudness variation, and strained voice subscores were improved via cessation of stimulation in both groups. Before surgery, the deteriorated group had significantly lower scores in the Stroop Color-Word Test and Digit Span compared to the stable group.

We previously reported that Parkinson's disease (PD) patients treated with subthalamic nucleus deep brain stimulation (STN-DBS) had distinct phenotypes of speech and voice disorders: hypokinetic dysarthria, stuttering, breathy voice, strained voice, and spastic dysarthria. However, changes over time remain unclear. In the present study, 32 consecutive PD patients were assessed before and up to 1 year after surgery (PD-DBS). Eleven medically treated PD patients were also assessed (PD-Med). Speech, voice, motor, and cognitive functions were evaluated. At baseline, the incidence of hypokinetic dysarthria (63% of PD-DBS vs. 82% of PD-Med), stuttering (50% vs. 45%), breathy voice (66% vs. 73%), and strained voice (3% vs. 9%) was similar between groups. At 1 year, a slight but significant deterioration in speech intelligibility (p < 0.001) and grade of dysphonia (p = 0.001) were observed only in PD-DBS group compared with baseline. During the follow-up, stuttering (9% vs. 18%) and breathy voice (13% vs. 9%) emerged in PD-DBS and PD-Med, but strained voice (28%) and spastic dysarthria (44%) emerged only in PD-DBS. After the stimulation was stopped, strained voice and spastic dysarthria improved in most patients, while stuttering and breathy voice improved in a minority of patients. These findings indicate that the most common DBS-induced speech and voice disorders are strained voice and spastic dysarthria and that STN-DBS potentially aggravates stuttering and breathy voice. An improved understanding of these types of disorders may help detect speech and voice deteriorations during the early phase and lead to appropriate treatments.

Motor cortex stimulation (MCS) has now become the preferred option for neurosurgical management of intractable central neuropathic pain such as post-stroke pain and trigeminal neuropathic pain. However, the efficacy of MCS for other central neuropathic pain such as pain resulting from spinal cord or brainstem lesions is unclear. We retrospectively reviewed 11 consecutive patients with intractable central neuropathic pain who underwent MCS in our institution. Eight patients had poststroke pain caused by thalamic hemorrhage (n ＝ 5) or infarction (n ＝ 3) (thalamic group). Two patients had postoperative neuropathic pain caused by spinal cord lesions, and one patient had facial pain caused by a brainstem lesion associated with multiple sclerosis (brainstem-spinal group). Visual analog scale and stimulation parameters were evaluated at 1 and 6 months postoperatively. MCS was effective for six of eight patients in the thalamic group, and all three patients in the brainstem-spinal group. These efficacies continued for 6 months after surgery without significant change in the stimulation parameters compared with the parameters at 1 month in both groups. The mean amplitude at 1 month and frequency at 6 months after surgery were significantly higher in the brainstem-spinal group than the thalamic group, although the patient number was small. MCS is effective for other central neuropathic pain, but higher intensity stimulation parameters may be necessary to gain adequate pain reduction.

Epilepsy surgery aims to control epilepsy by resecting the epileptogenic region while preserving function. In some patients with epileptogenic foci in and around functionally eloquent areas, awake surgery is implemented. We analyzed the surgical outcomes of such patients and discuss the clinical application of awake surgery for epilepsy. We examined five consecutive patients, in whom we performed lesionectomy for epilepsy with awake craniotomy, with postoperative follow-up > 2 years. All patients showed clear lesions on magnetic resonance imaging (MRI) in the right frontal (n = 1), left temporal (n = 1), and left parietal lobe (n = 3). Intraoperatively, under awake conditions, sensorimotor mapping was performed; primary motor and/or sensory areas were successfully identified in four cases, but not in one case of temporal craniotomy. Language mapping was performed in four cases, and language areas were identified in three cases. In one case with a left parietal arteriovenous malformation (AVM) scar, language centers were not identified, probably because of a functional shift. Electrocorticograms (ECoGs) were recorded in all cases, before and after resection. ECoG information changed surgical strategy during surgery in two of five cases. Postoperatively, no patient demonstrated neurological deterioration. Seizure disappeared in four of five cases (Engel class 1), but recurred after 2 years in the remaining patient due to tumor recurrence. Thus, for patients with epileptogenic foci in and around functionally eloquent areas, awake surgery allows maximal resection of the foci; intraoperative ECoG evaluation and functional mapping allow functional preservation. This leads to improved seizure control and functional outcomes.