Stimulation of the pedunculopontine nucleus area in Parkinson’s disease: effects on speech and intelligibility

Abstract

Improvement of gait disorders following pedunculopontine nucleus area stimulation in patients with Parkinson's disease has previously been reported and led us to propose this surgical treatment to patients who progressively developed severe gait disorders and freezing despite optimal dopaminergic drug treatment and subthalamic nucleus stimulation. The outcome of our prospective study on the first six patients was somewhat mitigated, as freezing of gait and falls related to freezing were improved by low frequency electrical stimulation of the pedunculopontine nucleus area in some, but not all, patients. Here, we report the speech data prospectively collected in these patients with Parkinson's disease. Indeed, because subthalamic nucleus surgery may lead to speech impairment and a worsening of dysarthria in some patients with Parkinson's disease, we felt it was important to precisely examine any possible modulations of speech for a novel target for deep brain stimulation. Our results suggested a trend towards speech degradation related to the pedunculopontine nucleus area surgery (off stimulation) for aero-phonatory control (maximum phonation time), phono-articulatory coordination (oral diadochokinesis) and speech intelligibility. Possibly, the observed speech degradation may also be linked to the clinical characteristics of the group of patients. The influence of pedunculopontine nucleus area stimulation per se was more complex, depending on the nature of the task: it had a deleterious effect on maximum phonation time and oral diadochokinesis, and mixed effects on speech intelligibility. Whereas levodopa intake and subthalamic nucleus stimulation alone had no and positive effects on speech dimensions, respectively, a negative interaction between the two treatments was observed both before and after pedunculopontine nucleus area surgery. This combination effect did not seem to be modulated by pedunculopontine nucleus area stimulation. Although limited in our group of patients, speech impairment following pedunculopontine nucleus area stimulation is a possible outcome that should be considered before undertaking such surgery. Deleterious effects could be dependent on electrode insertion in this brainstem structure, more than on current spread to nearby structures involved in speech control. The effect of deep brain stimulation on speech in patients with Parkinson's disease remains a challenging and exploratory research area.

Network effects of deep brain stimulation

“…A global effect of stimulation appears to be disruption of neuronal synchronization, particularly in the alpha and low beta frequency ranges. While this is shown to improve the motor symptoms of PD, cognitive function may be negatively affected in some cases after DBS, particularly if DLPFC and ACC activity are significantly affected (Pinto et al 2014).…”

Behavioral Treatments for Speech in Parkinson’s Disease: Meta-Analyses and Review of the Literature

“…On the other hand, another study failed to replicate this result revealing variable responses to LSVT post-treatment, including SyStematic review Atkinson-Clement, Sadat & Pinto future science group possible deteriorations [87]. In fact, deleterious combined effects between dopaminergic treatment and STN-DBS on PD speech have been reported recently [134], suggesting that the combination of STN-DBS and dopaminergic treatment may be related to the missing beneficial long-term effects of LSVT in this context.…”

Utilidad de la estimulación continua del núcleo pedunculopontino para el tratamiento de la enfermedad de Parkinson

“…En un estudio prospectivo, en el que se estimuló la zona del NPP en pacientes con EP, se obtuvieron resultados favorables en una pequeña cantidad de pacientes, y describieron lo que podría ser una interacción negativa entre la ECP y el uso de levodopa, tanto antes como después de la intervención; adicionalmente, describió problemas del habla en los pacientes tratados, principalmente disartria e inteligibilidad (capacidad de ser entendido) [11]. Estudios realizados en ratas y gatos demuestran que la lesión del NPP causa aquinesia y que su estimulación tiene algunos efectos positivos motores [12].…”