Nucleus Accumbens is Involved in Human Action Monitoring: Evidence from Invasive Electrophysiological Recordings

The Nucleus accumbens (Nacc) has been proposed to act as a limbic-motor interface. Here, using invasive intraoperative recordings in an awake patient suffering from obsessive-compulsive disease (OCD), we demonstrate that its activity is modulated by the quality of performance of the subject in a choice reaction time task designed to tap action monitoring processes. Action monitoring, that is, error detection and correction, is thought to be supported by a system involving the dopaminergic midbrain, the basal ganglia, and the medial prefrontal cortex. In surface electrophysiological recordings, action monitoring is indexed by an error-related negativity (ERN) appearing time-locked to the erroneous responses and emanating from the medial frontal cortex. In preoperative scalp recordings the patient's ERN was found to be significantly increased compared to a large (n = 83) normal sample, suggesting enhanced action monitoring processes. Intraoperatively, error-related modulations were obtained from the Nacc but not from a site 5 mm above. Importantly, cross-correlation analysis showed that error-related activity in the Nacc preceded surface activity by 40 ms. We propose that the Nacc is involved in action monitoring, possibly by using error signals from the dopaminergic midbrain to adjust the relative impact of limbic and prefrontal inputs on frontal control systems in order to optimize goal-directed behavior.

Deep brain stimulation to reward circuitry alleviates anhedonia in refractory major depression

Deep brain stimulation (DBS) to different sites allows interfering with dysfunctional network function implicated in major depression. Because a prominent clinical feature of depression is anhedonia--the inability to experience pleasure from previously pleasurable activities--and because there is clear evidence of dysfunctions of the reward system in depression, DBS to the nucleus accumbens might offer a new possibility to target depressive symptomatology in otherwise treatment-resistant depression. Three patients suffering from extremely resistant forms of depression, who did not respond to pharmacotherapy, psychotherapy, and electroconvulsive therapy, were implanted with bilateral DBS electrodes in the nucleus accumbens. Stimulation parameters were modified in a double-blind manner, and clinical ratings were assessed at each modification. Additionally, brain metabolism was assessed 1 week before and 1 week after stimulation onset. Clinical ratings improved in all three patients when the stimulator was on, and worsened in all three patients when the stimulator was turned off. Effects were observable immediately, and no side effects occurred in any of the patients. Using FDG-PET, significant changes in brain metabolism as a function of the stimulation in fronto-striatal networks were observed. No unwanted effects of DBS other than those directly related to the surgical procedure (eg pain at sites of implantation) were observed. Dysfunctions of the reward system--in which the nucleus accumbens is a key structure--are implicated in the neurobiology of major depression and might be responsible for impaired reward processing, as evidenced by the symptom of anhedonia. These preliminary findings suggest that DBS to the nucleus accumbens might be a hypothesis-guided approach for refractory major depression.

Tolosa-Hunt syndrome: MR imaging features in 15 patients with 20 episodes of painful ophthalmoplegia

PURPOSE

(a) To assess MR features in patients with Tolosa-Hunt syndrome (THS) and to (b) correlate MR findings with criteria derived from previously reported pathologic observations.

METHODS

Fifteen patients with twenty episodes of painful ophthalmoplegia prospectively selected according to International Headache Society (IHS) standards underwent MR examinations focused on the cavernous sinus. Initial examinations in 20 and follow-up MR images in 17 episodes were retrospectively reviewed by 3 independent observers.

RESULTS

The primary criteria: an enhancing soft tissue lesion within the cavernous sinus, increase in size and lateral bulging of the anterior cavernous sinus contour were consistently present in 15 initial episodes and in 5 recurrences (20/20). Agreement among observers was 100%. The secondary criteria: internal carotid artery narrowing in 7 patients, extension towards the superior orbital fissure in 13 and orbital apex involvement in 8 patients were unanimously agreed upon in 87.5%, 86.6% and 80%. Complete resolution of findings was observed on follow-up studies.

CONCLUSION

In patients with THS the MR features conform to previously reported pathologic findings. MR features are evocative of THS when an increase in size and bulging of the dural contour of the anterior CS supplemented by carotid artery involvement and extension towards the orbit are present. Resolution of findings within 6 months is required to support the diagnosis.

Mood improvement after deep brain stimulation of the internal globus pallidus for tardive dyskinesia in a patient suffering from major depression

Deep brain stimulation (DBS) has the unique characteristic to very precisely target brain structures being part of functional brain circuits in order to reversibly modulate their function. It is an established adjunctive treatment of advanced Parkinson's disease and has virtually replaced ablative techniques in this indication. Several cases have been published relating effectiveness in neuroleptics-induced tardive dyskinesia. It is also investigated as a potential treatment of mood disorders. We report on the case of a 62 years old female suffering from a treatment refractory major depressive episode with comorbid neuroleptic-induced tardive dyskinesia. She was implanted a deep brain stimulation treatment system bilaterally in the globus pallidus internus and stimulated for 18 months. As well the dyskinesia as also the symptoms of depression improved substantially as measured by the Hamilton Rating Scale of Depression (HRSD) score and the Burke-Fahn-Marsden-Dystonia-Rating-Scale (BFMDRS) score. Scores dropped for HRSD from 26 at baseline preoperatively to 13 after 18 months; and for BFMDRS from 27 to 17.5. This case illustrates the potential of deep brain stimulation as a technique to be investigated in the treatment of severe and disabling psychiatric and movement disorders. DBS at different intracerebral targets being actually investigated for major depression might have similar antidepressant properties because they interact with the same cortico-basal ganglia-thalamocortical network found to be dysfunctional in major depression.

Remission of alcohol dependency following deep brain stimulation of the nucleus accumbens: valuable therapeutic implications?

Chronic consumption of alcohol represents one of the greatest health and socioeconomic problems worldwide. We report on a 54-year-old patient with a severe anxiety disorder and secondary depressive disorder in whom bilateral deep brain stimulation (DBS) of the nucleus accumbens was carried out. Despite the absence of desired improvement in his primary disorder, we observed a remarkable although not primarily intended alleviation of the patient's comorbid alcohol dependency. Our case report demonstrates the extremely effective treatment of alcohol dependency by means of DBS of the nucleus accumbens and may reveal new prospects in overcoming therapy resistance in dependencies in general.

Behavioural and physiological effects of electrical stimulation in the nucleus accumbens: a review

Electrical stimulation (ES) in the brain is becoming a new treatment option in patients with treatment-resistant obsessive-compulsive disorder (OCD). A possible brain target might be the nucleus accumbens (NACC). This review aims to summarise the behavioural and physiological effects of ES in the NACC in humans and in animals and to discuss these findings with regard to neuroanatomical, electrophysiological and behavioural insights. The results clearly demonstrate that ES in the NACC has an effect on reward, activity, fight-or-flight, exploratory behaviour and food intake, with evidence for only moderate physiological effects. Seizures were rarely observed. Finally, the results of ES studies in patients with treatment-resistant OCD and in animal models for OCD are promising.

Pathological crying induced by deep brain stimulation

Pathological crying (PLC)--an affective gesture without any or an adequate emotion--occurs with various diseases. A recent theory suggests that PLC is caused by a disruption of higher order cortical association areas from the cerebellum which computes profiles of psychomotor responses. We report a patient with Parkinson's disease who developed PLC during stimulation of the subthalamic nucleus (STN) predominantly of the right hemisphere. Positron emission tomography imaging showed thalamo-ponto-cerebellar activation during such stimulation. These findings indicate that the STN and possibly also ponto-cerebellar pathways are involved in psychomotor control and in the modulation of PLC.

Intrathecal opioids for intractable pain syndromes

For more than 20 years intrathecal opioid application with implantable pumps is an option for selected patients with malignant as well as non-malignant pain. In general, most types of pain should be treatable by opioid medication. However, the associated systemic side-effects such as nausea, vomiting, constipation or the risk of suppression of the central nervous system hinder the application of oral or intravenous opioid therapy as a sole, widely applicable treatment. Causes of non-malignant pain that may represent an indication for intrathecal drug-delivery systems include: failed back syndrome, neuropathic pain, axial spinal pain, complex regional pain syndrome, diffuse pain, brachial plexitis, central pain, failed spinal cord stimulation (SCS) therapy, arachnoiditis, poststroke pain, spinal cord injury pain and peripheral neuropathy. Due to the proximity to the receptor sites, the therapeutic effect of intrathecal drug application lasts longer and the rate of systemic side effects is reduced. Before definitive pump implantation, the therapeutic effect of intrathecal opioid therapy is tested with an external pump. If there is no clear and satisfactory effect in this trial application, pump implantation is not indicated. In our patients, with a follow-up exceeding 3 years, the reduction of non-malignant pain (assessed with the Visual Analogue Scale, VAS) was good or excellent (pain decrease >50%) in 71.3% of the patients, fair (VAS 5-6) in 19.8% and poor (VAS 7-10) in 8.9%. After 3 years of continuous treatment, we observed catheter-related technical problems (catheter dislocation, obstruction, kinking, disconnection or rupture) in 17 of 165 patients. Pump malfunctions were very rare (8 of 165 cases) and limited to older pump types. Reversible, specific drug-related side effects of long-term therapy with intrathecal pumps developed in 32 of the 165 patients. In our series, the mean serum/cerebrospinal fluid (CSF) concentration ratio for morphine was 1/3000, which explains the low rate of systemic side effects. Local diffusion difficulties in CSF cause an uneven distribution of morphine in CSF. Therefore the clinical effect is markedly influenced by the position of the catheter tip, a fact that should be kept in mind during catheter implantation. Intrathecal drug application is cost effective and can significantly improve the quality of life in selected patients. An intensive training in this method and awareness of its specific complications is necessary for everyone to participate in the consulting and implanting team. Pumps for chronic intrathecal opioid application should only be implanted in specialized centers.

Subthalamic-thalamic DBS in a case with spinocerebellar ataxia type 2 and severe tremor-A unusual clinical benefit

This is a single case report of a patient with spinocerebellar ataxia type 2 (SCA2) and severe tremor. Whereas disease progression with prevailing ataxia and dysmetria was slow over the first symptomatic 6 years, 6 months prior to operation were characterized by the development of a severe, debilitating postural tremor rendering the patient unable to independently sit, stand, speak, or swallow. Deep brain stimulation (DBS) at a subthalamic-thalamic electrode position almost completely arrested her tremor. The patient regained the functional state prior to her rapid disease progression allowing a restricted range of daily activities. Her condition has remained approximately stable over the two postoperative years to date. In addition to the efficacy of DBS on cerebellar tremor, the results illustrate a remarkable improvement of the patient's general condition and independence.

COMBINED X-RAY AND MAGNETIC RESONANCE IMAGING FACILITY

OBJECTIVE

To assess the feasibility of a hybrid imaging setup combining x-ray and magnetic resonance imaging (MRI) in the setting of both stereotactic and functional neurosurgery.

METHODS

A combined x-ray and MRI scanning facility with a trolley system for a fast patient transfer between both modalities was installed in a neurosurgical setting. A registration algorithm for fusion of MRI scans and x-ray images was derived for augmentation of fluoroscopic x-ray projection images with MRI scan data, such as anatomic structures and planned probe trajectories. Phantom measurements were obtained between both modalities for estimation of registration accuracy. Practical application of our system in stereotactic and functional neurosurgery was tested in brachytherapy, deep brain stimulation, and motor cortex stimulation.

RESULTS

Phantom measurements yielded a mean spatial deviation of 0.7 +/- 0.3 mm with a maximum deviation of 1.1 mm for MRI scans versus x-rays. Augmentation of x-ray images with MRI scan data allowed intraoperative verification of the planned trajectory and target in three types of neurosurgical procedures: positioning iodine seeds in brachytherapy in one case with cerebellar metastasis, placement of electrodes for deep brain stimulation in two cases of advanced Parkinson's disease, and placement of an epidural grid for motor cortex stimulation in two cases of intractable pain.

CONCLUSION

Combined x-ray and MRI-guided stereotactic and functional neurosurgery is feasible. Augmentation of x-ray projection images with MRI scan data, such as planned probe trajectories and MRI scan segmented anatomic structures may be beneficial for probe guidance in stereotactic and functional neurosurgery.

Deep brain stimulation for Parkinson's disease

Indications for the treatment of Parkinson's disease (PD) with deep brain stimulation (DBS) are severe, therapy refractory tremor and complications of long-term levodopa uptake. Since its first application DBS has become a standard therapy for these patients. Theoretically, the ventrolateral part of the internal pallidum (GPI) or the subthalamic nucleus (STN) are suitable targets in order to treat all cardinal symptoms of patients in an advanced stage of PD stereotactically. Although clinical efficacy of both GPI or STN stimulation is obviously comparable, it has become widely accepted to prefer STN over GPI DBS. If PD-associated, medically intractable tremor is the most disabling symptom, stimulation of the ventrolateral motor thalamus can be an alternative. Anatomical targets for DBS are small and located in critical brain areas. Furthermore, this type of surgery is highly elective. As a consequence, high resolution multiplanar imaging and adequate treatment planning software are indispensable prerequisites for DBS surgery. Currently, commercially available impulse generators deliver a permanent high frequency periodic pulse train stimulation that interacts rather unspecifically with the firing pattern of both normal and pathological neurons. Prospectively, the development of more specific stimulation paradigms may help to improve the efficacy of this treatment modality.

Uveitis: Intravitreales Triamcinolon bei zystoidem Makulaödem

BACKGROUND

Cystoid macular edema (CME) is the most frequent cause of severe loss of visual acuity in uveitis. Among the systemic corticosteroids and immunosuppressive agents, the local use of intravitreal triamcinolone acetate (TA) is evaluated.

METHODS AND PATIENTS

Intravitreal injections of 10 mg TA were performed in ten eyes of six patients with persisting uveitic CME in spite of systemic cortisone or immunosuppressive therapy.

RESULTS

The mean follow-up time was 9.8 months (range: 3-18). Visual acuity increased from 0.58 logMAR to 0.21 logMAR. In two eyes of one patient, repeated intravitreal injections of TA were necessary. Side effects included a increase of intraocular pressure (IOP) up to 25 mmHg or more in 30% of the eyes. In these three eyes, IOP was successfully controlled by local antiglaucomatous therapy (IOP < or = 20 mmHg). The dosage of systemic steroids had to be augmented in two eyes. In no patient was injection-related endophthalmitis, vitreous hemorrhage or retinal detachment observed.

CONCLUSIONS

Intravitreal TA is an effective local therapy for CME due to uveitis without systemic side effects. It cannot replace the systemic basal therapy of uveitis, since the long-term effects are limited. It can be used as a bridging therapy until a systemic immunosuppression is started. It may, furthermore, be a therapeutic option when side effects of immunosuppressive agents are expected.