Shifting from constant-voltage to constant-current in Parkinson's disease patients with chronic stimulation.

The study aimed to evaluate safety and efficacy of shifting stimulation settings from constant-voltage (CV) to constant-current (CC) programming in patients with Parkinson's disease (PD) and chronic subthalamic nucleus deep brain stimulation (STN DBS). Twenty PD patients with chronic STN DBS set in CV programming were shifted to CC and followed for 3 months; the other stimulation settings and the medication regimen remained unchanged. Side effects, motor, non-motor, executive functions, and impedance were assessed at baseline and during follow-up. No adverse events were observed at time of shifting or during CC stimulation. Motor and non-motor measures remained unchanged at follow-up despite impedance decreased. Compared to baseline, inhibition processes improved at follow-up. The shifting strategy was well tolerated and the clinical outcome was maintained with no need to adjust stimulation settings or medications notwithstanding a decrease of impedance. Improvement of inhibition processes is a finding which needed further investigation.

Sensorimotor integration in patients with parkinsonian type multisystem atrophy.

Sensorimotor integration is an essential feature of the central nervous system that contributes to the accurate performance of motor tasks. Some patients with multiple system atrophy with parkinsonian features (MSAp) exhibit clinical signs compatible with an abnormal central nervous system excitability to somatosensory inputs, such as action myoclonus or enhanced cutaneo-muscular reflexes. To investigate further the site where such dysfunction in sensorimotor integration takes place, we examined the inhibitory effects of a cutaneous afferent volley at two different levels of the motor system in 10 MSAp patients and in 10 age-matched healthy volunteers. Electrical digital nerve stimuli were given as the conditioning stimulus for the motor evoked potentials (MEP) elicited by transcranial magnetic stimulation in hand muscles, and for the blink reflex responses obtained in the orbicularis oculi muscles by supraorbital nerve stimulation. Intervals for the conditioning were 20 to 50 ms for the MEP and 90 to 110 ms for the blink reflex. The MEP was significantly inhibited in test trials in healthy volunteers, reaching a mean of 32% of the baseline values at the ISI of 35 ms. Significant inhibition occurred also in the blink reflex, in which the R2 response was a mean of 12% of baseline values at the ISI of 100 ms. The inhibitory effects were abnormally reduced in 8 patients on the MEP, and in 7 patients on the blink reflex. There were significant group differences between patients and control subjects in the size of the conditioned MEP and blink reflex. These results suggest that sensorimotor integration is abnormal in patients with MSAp in at least two central nervous system sites: the sensorimotor cortex, and the brainstem reticular formation.

Bipolar affective disorder and Parkinson's disease: a rare, insidious and often unrecognized association.

Five patients (4 women) with Parkinson's disease (PD) and primary major psychiatric disorder (PMPD) meeting DSM-IV criteria for the diagnosis of bipolar affective disorder (BAD) were studied. Four patients had early onset PD. Four developed a severe psychiatric disorder a few years after starting dopaminergic therapy in presence of a mild motor disability and a mild cognitive impairment, with no evidence of cerebral atrophy at CT or MRI. Two patients developed a clear manic episode; the other three presented a severe depressive episode (in one case featuring a Cotard syndrome). None showed previous signs of long term L-dopa treatment syndrome (LTS), hallucinosis or other minor psychiatric disorders. The two manic episodes occurred shortly after an increase of dopaminergic therapy and in one case rapid cyclic mood fluctuations were observed. At the onset of psychiatric symptoms, all patients had an unspecific diagnosis of chronic delusional hallucinatory psychosis (CDHP).

Chronic delusional hallucinatory psychosis in early-onset Parkinson's disease: drug-induced complication or sign of an idiopathic psychiatric illness?

Chronic delusional psychosis with hallucinations (CDHP) is commonly assumed to complicate the later stages of Parkinson's disease, as a side effect of antiparkinsonian medication. We studied 7 patients with early onset PD, who had developed psychiatric manifestations consisting in CDHP after a few years of antiparkinsonian therapy. All patients underwent a neurological, psychiatric and brain imaging (CT or MRI) evaluation. Detailed clinical history was recorded in order to reveal prior psychiatric illness and to analyse the relationship between neurological disease, cognitive impairment and psychosis. Our findings suggest that CDHP occurring in patients with early onset PD, normal or slightly impaired cognitive functions and normal CT/MRI scans is invariably the expression of a coexisting psychiatric illness which prior to onset of the neurologic disease had not been correctly diagnosed and which has been disclosed by dopaminergic therapy.