The role of the dorsal Anterior Cingulate Cortex (dACC) in a cognitive and emotional counting Stroop task: Two cases.

BACKGROUND: The anterior cingulate cortex (ACC) has been implicated in both cognitive and emotional processing, with cognitive information proposed to be processed through the dorsal/caudal ACC and emotional information through the rostral/ventral ACC. OBJECTIVE: The objective of this study is to investigate the role of the dorsal anterior cingulate cortex (dACC) in cognitive and emotional processing using a cognitive and emotional counting Stroop task in two patients in whom abnormalities in the dACC were identified and treated. METHODS: Two patients performed the cognitive and emotional counting Stroop task before and after treatment to examine whether the dACC has a specific or more general processing function. RESULTS: We observed an overall improvement in the emotional, cognitive, and neutral trials of the counting Stroop task after the intervention, indicating that the dACC is not a subregion of the ACC that only contributes to a specific domain. CONCLUSION: This study reveals that the dACC is not just a subregion of the ACC that contributes to a specific cognitive function, but is rather part of a salience network that influences general brain functioning, influencing cognitive as well as emotional processing.

Occipital nerve stimulation in fibromyalgia: a double-blind placebo-controlled pilot study with a six-month follow-up.

OBJECTIVE: The goal of this study is to evaluate the effectiveness of occipital nerve stimulation (ONS) as a surgical treatment for fibromyalgia in a placebo-controlled design. MATERIALS AND METHODS: Eleven patients were selected based on the American College of Rheumatology-90 criteria and implanted with an occipital nerve trial-lead stimulator. Baseline scores for pain, mood, and fatigue were acquired, and patients were randomized in a ten-week double-blinded crossover design with placebo and effective subsensory threshold stimulation (no paresthesias). After finalizing the trial, nine patients were implanted permanently; evaluation was performed prior to surgery and at six months after surgery for pain, fatigue, and mood of the number of trigger points and overall morbidity. RESULTS: Significant results were found during the trial for a decrease in pain intensity (39.74%) on visual analogue scale (VAS; p < 0.001) and pain catastrophizing scale (PCS) during effective stimulation. A total of 9/11 patients responded to trial treatment; however, in two patients, this might be a placebo effect, recognizable due to the study design. Six months after permanent implantation, pain intensity remained decreased (44.01%) on VAS (p < 0.05). Besides the VAS, significant changes were noted for PCS, fatigue (modified fatigue impact scale), the number of trigger points, and overall morbidity (fibromyalgia impact questionnaire). There were no serious adverse events. CONCLUSIONS: Our data strongly suggest that ONS is beneficial in the treatment of fibromyalgia. The beneficial effects are stable at six months after permanent implantation. Subsensory threshold stimulation is feasible in designing a placebo-controlled trial.

C2 subcutaneous stimulation for failed back surgery syndrome: a case report.

OBJECTIVE: Failed back surgery syndrome (FBSS) is a term embracing a constellation of conditions that describes persistent or recurring low back pain, with or without sciatica following one or more spine surgeries. It has been shown in animals that electrical stimulation of the high cervical C2 area can suppress pain stimuli derived from the L5-S1 dermatome. It is unknown whether C2 electrical stimulation in humans can be used to treat pain derived from the L5-S1 area, and a case is reported in which subcutaneous C2 is applied to treat FBSS. CASE: A patient presents to the neuromodulation clinic because of FBSS (after three lumbar diskectomies) and noninvasive neuromodulation is performed consisting of transcutaneous electrical nerve stimulation (TENS) at C2. The C2 TENS stimulation is successful in improving pain. It induces paresthesias in the C2 dermatome above a certain amplitude threshold, but does not generate paresthesias in the pain area. However, the patient becomes allergic to the skin-applied TENS electrodes and therefore a new treatment strategy is discussed with the patient. A subcutaneous C2 electrode is inserted under local anesthesia, and attached to an external pulse generator. METHODS: Three stimulation designs are tested: a classical tonic stimulation, consisting of 40 Hz stimulation, a placebo, and a burst stimulation, consisting of 40 Hz burst mode, with five spikes delivered at 500 Hz at 1000 µsec pulse width and 1000 µsec interspike interval. RESULTS: The patient's stimulation results demonstrate that burst mode is superior to placebo and tonic mode, and she receives a fully implanted C2 electrode connected to an internal pulse generator via an extension wire. CONCLUSION: The burst design is capable of both suppressing the least and worst pain effectively, and she has remained almost pain-free for over three years.

Theta-gamma dysrhythmia and auditory phantom perception.

Tinnitus is considered an auditory phantom percept analogous to phantom pain. Thalamocortical dysrhythmia has been proposed as a possible pathophysiological mechanism for both tinnitus and pain. Thalamocortical dysrhythmia refers to a persistent pathological resting state theta-gamma coupling that is spatially localized at an area where normally alpha oscillations predominate. Auditory cortex stimulation via implanted electrodes has been developed to treat tinnitus, targeting an area of activation on functional MR imaging elicited by tinnitus-matched sound presentation. The authors describe a case in which clinical improvement was correlated with changes in intracranial recordings. Maximal tinnitus suppression was obtained by current delivery exactly at the blood oxygen level-dependent activation hotspot, which colocalizes with increased gamma and theta activity, in contrast to the other electrode poles, which demonstrated a normal alpha peak. These spectral changes normalized when stimulation induced tinnitus suppression, both on electrode and source-localized electroencephalography recordings. These data suggest that thetagamma coupling as proposed by the thalamocortical dysrhythmia model might be causally related to a conscious auditory phantom percept.

Transcranial magnetic stimulation and extradural electrodes implanted on secondary auditory cortex for tinnitus suppression.

OBJECT: Tinnitus is a prevalent symptom, with clinical, pathophysiological, and treatment features analogous to pain. Noninvasive transcranial magnetic stimulation (TMS) and intracranial auditory cortex stimulation (ACS) via implanted electrodes into the primary or overlying the secondary auditory cortex have been developed to treat severe cases of intractable tinnitus. METHODS: A series of 43 patients who benefited transiently from 2 separate placebo-controlled TMS sessions underwent implantation of auditory cortex electrodes. Targeting was based on blood oxygen level-dependent activation evoked by tinnitus-matched sound, using functional MR imaging-guided neuronavigation. RESULTS: Thirty-seven percent of the patients responded to ACS with tonic stimulation. Of the 63% who were nonresponders, half benefited from burst stimulation. In total, 33% remained unaffected by the ACS. The average tinnitus reduction was 53% for the entire group. Burst stimulation was capable of suppressing tinnitus in more patients and was better than tonic stimulation, especially for noise-like tinnitus. For pure tone tinnitus, there were no differences between the 2 stimulation designs. The average pure tone tinnitus improvement was 71% versus 37% for noise-like tinnitus and 29% for a combination of both pure tone and noise-like tinnitus. Transcranial magnetic stimulation did not predict response to ACS, but in ACS responders, a correlation (r = 0.38) between the amount of TMS and ACS existed. A patient's sex, age, or tinnitus duration did not influence treatment outcome. CONCLUSIONS: Intracranial ACS might become a valuable treatment option for severe intractable tinnitus. Better understanding of the pathophysiological mechanisms of tinnitus, predictive functional imaging tests, new stimulation designs, and other stimulation targets are needed to improve ACS results.

Burst spinal cord stimulation: toward paresthesia-free pain suppression.

INTRODUCTION: Spinal cord stimulation is commonly used for neuropathic pain modulation. The major side effect is the onset of paresthesia. The authors describe a new stimulation design that suppresses pain as well as, or even better than, the currently used stimulation, but without creating paresthesia. METHODS: A spinal cord electrode (Lamitrode) for neuropathic pain was implanted in 12 patients via laminectomy: 4 at the C2 level and 7 at the T8-T9 level for cervicobrachialgia and lumboischialgia, respectively (1 at T11 at another center). During external stimulation, the patients received the classic tonic stimulation (40 or 50 Hz) and the new burst stimulation (40-Hz burst with 5 spikes at 500 Hz per burst). RESULTS: Pain scores were measured using a visual analog scale and the McGill Short Form preoperatively and during tonic and burst stimulation. Paresthesia was scored as present or not present. Burst stimulation was significantly better for pain suppression, by both the visual analog scale score and the McGill Short Form score. Paresthesia was present in 92% of patients during tonic stimulation, and in only 17% during burst stimulation. Average follow-up was 20.5 months. CONCLUSION: The authors present a new method of spinal cord stimulation using bursts that suppress neuropathic pain without the mandatory paresthesia. Pain suppression seems as good as or potentially better than that achieved with the currently used stimulation. Average follow-up after nearly 2 years (20.5 months) suggests that this stimulation design is stable.

Tinnitus intensity dependent gamma oscillations of the contralateral auditory cortex.

BACKGROUND: Non-pulsatile tinnitus is considered a subjective auditory phantom phenomenon present in 10 to 15% of the population. Tinnitus as a phantom phenomenon is related to hyperactivity and reorganization of the auditory cortex. Magnetoencephalography studies demonstrate a correlation between gamma band activity in the contralateral auditory cortex and the presence of tinnitus. The present study aims to investigate the relation between objective gamma-band activity in the contralateral auditory cortex and subjective tinnitus loudness scores. METHODS AND FINDINGS: In unilateral tinnitus patients (N = 15; 10 right, 5 left) source analysis of resting state electroencephalographic gamma band oscillations shows a strong positive correlation with Visual Analogue Scale loudness scores in the contralateral auditory cortex (max r = 0.73, p<0.05). CONCLUSION: Auditory phantom percepts thus show similar sound level dependent activation of the contralateral auditory cortex as observed in normal audition. In view of recent consciousness models and tinnitus network models these results suggest tinnitus loudness is coded by gamma band activity in the contralateral auditory cortex but might not, by itself, be responsible for tinnitus perception.