Neuronavigation maximizes accuracy and precision in TMS positioning: Evidence from 11,230 distance, angle, and electric field modeling measurements

BACKGROUND

Researchers and clinicians have traditionally relied on elastic caps with markings to reposition the transcranial magnetic stimulation (TMS) coil between trains and sessions. Newer neuronavigation technology co-registers the patient's head and structural magnetic resonance imaging (MRI) scan, providing the researcher with real-time feedback about how to adjust the coil to be on-target. However, there has been no head to head comparison of accuracy and precision across treatment sessions.

OBJECTIVE

/Hypothesis: In this two-part study, we compared elastic cap and neuronavigation targeting methodologies on distance, angle, and electric field (E-field) magnitude values.

METHODS

In 42 participants receiving up to 50 total accelerated rTMS sessions in 5 days, we compared cap and neuronavigation targeting approaches in 3408 distance and 6816 angle measurements. In Experiment 1, TMS administrators saved an on-target neuronavigation location at Beam F3, which served as the landmark for all other measurements. Next, the operators placed the TMS coil based on cap markings or neuronavigation software to measure the distance and angle differences from the on-target sample. In Experiment 2, we saved each XYZ coordinate of the TMS coil from cap and neuronavigation targeting in 12 participants to compare the E-field magnitude differences at the cortical prefrontal target in 1106 cap and neuronavigation models.

RESULTS

Cap targeting was significantly off-target for distance, placing the coil an average of 10.66 mm off-target (Standard error of the mean; SEM = 0.19 mm) compared to 0.3 mm (SEM = 0.03 mm) for neuronavigation (p < 0.0001). Cap targeting also significantly deviated for angles off-target, averaging 7.79 roll/pitch degrees (SEM = 1.07°) off-target and 5.99 yaw degrees (SEM = 0.12°) off-target; in comparison, neuronavigation targeting positioned the coil 0.34 roll/pitch degrees (SEM = 0.01°) and 0.22 yaw (SEM = 0.004°) off-target (both p < 0.0001). Further analyses revealed that there were significant inter-operator differences on distance and angle positioning for F3 (all p < 0.05), but not neuronavigation. Lastly, cap targeting resulted in significantly lower E-fields at the intended prefrontal cortical target, with equivalent E-fields as 110.7% motor threshold (MT; range = 58.3-127.4%) stimulation vs. 119.9% MT (range = 115-123.3%) from neuronavigated targeting with 120% MT stimulation applied (p < 0.001).

CONCLUSIONS

Cap-based targeting is an inherent source of target variability compared to neuronavigation. Additionally, cap-based coil placement is more prone to differences across operators. Off-target coil placement secondary to cap-based measurements results in significantly lower amounts of stimulation reaching the cortical target, with some individuals receiving only 48.6% of the intended on-target E-field. Neuronavigation technology enables more precise and accurate TMS positioning, resulting in the intended stimulation intensities at the targeted cortical level.

Pyrethroid resistance/susceptibility and differential urban/rural distribution of Anopheles arabiensis and An. gambiae s.s. malaria vectors in Nigeria and Ghana

Resistance to pyrethroid insecticides and DDT caused by the kdr gene in the malaria vector Anopheles gambiae Giles s.s. (Diptera: Culicidae) has been reported in several West African countries. To test for pyrethroid resistance in two more countries, we sampled populations of the An. gambiae complex from south-western Ghana and from urban and rural localities in Ogun State, south-west Nigeria. Adult mosquitoes, reared from field-collected larvae, were exposed to the WHO-recommended discriminating dosage of exposure for 1 h to DDT 4%, deltamethrin 0.05% or permethrin 0.75% and mortality was recorded 24 h post-exposure. Susceptibility of An. gambiae s.l. to DDT was 94-100% in Ghana and 72-100% in Nigeria, indicating low levels of DDT resistance. Deltamethrin gave the highest mortality rates: 97-100% in Ghana, 95-100% in Nigeria. Ghanaian samples of An. gambiae s.l. were fully susceptible to permethrin, whereas some resistance to permethrin was detected at 4/5 Nigerian localities (percentage mortalities 75, 82, 88, 90 and 100%), with survivors including both An. arabiensis Patton and An. gambiae s.s. identified by PCR assay. Even so, the mean knockdown time was not significantly different from a susceptible reference strain, indicating absence or low frequency of kdr-type resistance. Such low levels of pyrethroid resistance are unlikely to impair the effectiveness of pyrethroid-impregnated bednets against malaria transmission. Among Nigerian samples of An. gambiae s.l., the majority from two urban localities were identified as An. arabiensis, whereas the majority from rural localities were An. gambiae s.s. These findings are consistent with those of M. Coluzzi et al. (1979). Differences of ecological distribution between molecular forms of An. gambiae s.s. were also found, with rural samples almost exclusively of the S-form, whereas the M-form predominated in urban samples. It is suggested that 'urban island' populations of An. arabiensis and of An. gambiae s.s. M-form in the rainforest belt of West Africa might be appropriate targets for elimination of these malaria vectors by the sterile insect technique.

A transdiagnostic review of safety, efficacy, and parameter space in accelerated transcranial magnetic stimulation

BACKGROUND

Accelerated transcranial magnetic stimulation (aTMS) is an emerging delivery schedule of repetitive TMS (rTMS). TMS is "accelerated" by applying two or more stimulation sessions within a day. This three-part review comprehensively reports the safety/tolerability, efficacy, and stimulation parameters affecting response across disorders.

METHODS

We used the PubMed database to identify studies administering aTMS, which we defined as applying at least two rTMS sessions within one day.

RESULTS

Our targeted literature search identified 85 aTMS studies across 18 diagnostic and healthy control groups published from July 2001 to June 2022. Excluding overlapping populations, 63 studies delivered 43,873 aTMS sessions using low frequency, high frequency, and theta burst stimulation in 1543 participants. Regarding safety, aTMS studies had similar seizure and side effect incidence rates to those reported for once daily rTMS. One seizure was reported from aTMS (0.0023% of aTMS sessions, compared with 0.0075% in once daily rTMS). The most common side effects were acute headache (28.4%), fatigue (8.6%), and scalp discomfort (8.3%), with all others under 5%. We evaluated aTMS efficacy in 23 depression studies (the condition with the most studies), finding an average response rate of 42.4% and remission rate of 28.4% (range = 0-90.5% for both). Regarding parameters, aTMS studies ranged from 2 to 10 sessions per day over 2-30 treatment days, 10-640 min between sessions, and a total of 9-104 total accelerated TMS sessions per participant (including tapering sessions). Qualitatively, response rate tends to be higher with an increasing number of sessions per day, total sessions, and total pulses.

DISCUSSION

The literature to date suggests that aTMS is safe and well-tolerated across conditions. Taken together, these early studies suggest potential effectiveness even in highly treatment refractory conditions with the added potential to reduce patient burden while also expediting response time. Future studies are warranted to systematically investigate how key aTMS parameters affect treatment outcome and durability.

Electric Field Strength From Prefrontal Transcranial Direct Current Stimulation Determines Degree of Working Memory Response: A Potential Application of Reverse-Calculation Modeling?

BACKGROUND

Transcranial direct current stimulation (tDCS) for working memory is an enticing treatment, but there is mixed evidence to date.

OBJECTIVES

We tested the effects of electric field strength from uniform 2 mA dosing on working memory change from prestimulation to poststimulation. Second, we statistically evaluated a reverse-calculation method of individualizing tDCS dose and its effect on normalizing electric field at the cortex.

MATERIALS AND METHODS

We performed electric field modeling on a data set of 28 healthy older adults (15 women, mean age = 73.7, SD = 7.3) who received ten sessions of active 2 mA tDCS (N = 14) or sham tDCS (N = 14) applied over bilateral dorsolateral prefrontal cortices (DLPFC) in a triple-blind design. We evaluated the relationship between electric field strength and working memory change on an N-back task in conditions of above-median, high electric field from active 2 mA (N = 7), below-median, low electric field from active 2 mA (N = 7), and sham (N = 14) at regions of interest (ROI) at the left and right DLPFC. We then determined the individualized reverse-calculation dose to produce the group average electric field and measured the electric field variance between uniform 2 mA doses vs individualized reverse-calculation doses at the same ROIs.

RESULTS

Working memory improvements from pre- to post-tDCS were significant for the above-median electric field from active 2 mA condition at the left DLPFC (mixed ANOVA, p = 0.013). Furthermore, reverse-calculation modeling significantly reduced electric field variance at both ROIs (Levene's test; p < 0.001).

CONCLUSIONS

Higher electric fields at the left DLPFC from uniform 2 mA doses appear to drive working memory improvements from tDCS. Individualized doses from reverse-calculation modeling significantly reduce electric field variance at the cortex. Taken together, using reverse-calculation modeling to produce the same, high electric fields at the cortex across participants may produce more effective future tDCS treatments for working memory.

Malaria prevalence in north-eastern Nigeria: a cross-sectional study

OBJECTIVE

To assess the prevalence of malaria parasitemia in north-east Nigeria and to evaluate the measures for the prevention of malaria.

METHODS

A village in north-eastern Nigeria was selected for the cross sectional study at the height of the rainy season in October 2011. A total of 550 inhabitants of a hamlet were recruited for this study. After obtaining the consent individuals received a structured interview and were tested for malaria parasites in their blood films. Recruits testing positive for malaria were given a course of artemesinin-based combination therapy (ACT).

RESULTS

A total of 497 inhabitants representing approximately 90 percent of the population participated: a quarter of the study group carried malaria parasitesexclusively Plasmodium falciparum(P. falciparum)-representing a P. falciparum parasite rate (PfPR) of 24.5%. Besides, 53/138 in the age group of 2 to < 10 years old children tested positive for P. falciparum representing a PfPR2-10 value of 38.4%. Malaria control measures were used in just under a third (157/497) of this cohort. Despite these measures 28/157 (17.8%) still tested positive for P. falciparum.

CONCLUSIONS

The malaria burden is overestimated for this region in north-east Nigeria. The findings support an intermediate pattern of malaria endemicity. The 30% bed nets coverage for malaria control is well below the WHO estimates for 2011.

[The work of medical doctors on psychiatric wards: an analysis of everyday activities]

In Germany, the economic situation of psychiatric hospitals has markedly changed during the last years. Whilst the number of patients has steadily increased, many clinics considerably reduced the number of therapeutic staff due to an increasing lack of financial support. The German psychiatry personnel regulations act defines the number of therapeutic staff required for an adequate psychiatric treatment, but the requirements of this regulations act nowadays are widely missed in most of the German psychiatric hospitals. This severely affects the therapeutic work on psychiatric wards. This study analyses tasks and activities of medical doctors on psychiatric wards and compares the hours spent with various types of activities with the amount of time that should be spent according to the personnel regulations act. Results show that doctors spend much more time with documentation and administrative work than originally intended by the personnel regulations act. They compensate this mainly by a reduction of time spent in direct contact with the patients. In this context, the number of psychotherapy sessions as well as sessions with the patients' relatives has been considerably reduced, whereas the time spent for emergency intervention and basic treatment still corresponds to the calculations according to the personnel regulations act. All in all, the results show that a reduction of therapeutic staff in psychiatric hospitals directly leads to a change in treatment settings with a focus on less individual treatment options.

[Withdrawal therapy of patients with alcoholism and nicotine dependence with carcinomas in the area of the head and neck. Luxury or necessity?]

PURPOSE

Alcohol and nicotine abuse play a major role in the etiology of oral squamous cell carcinomas. In the present study, we investigated the number of patients with oral/oropharyngeal carcinomas who regularly consume alcohol and nicotine and what type of specific treatment should be prescribed for the addiction.

PATIENTS AND METHOD

A total of 105 patients (90 men, 15 women) with oral/oropharyngeal squamous cell carcinomas were studied based on catamnestic data as well as a special questionnaire designed to assess drinking and smoking habits (40 g alcohol/day for men and 20 g alcohol/day for women was taken as the standard measure for those considered at risk for alcoholism). For smokers, the number of packs smoked per year was determined and compared to clinical data (i.e., tumor size, location) and laboratory data (gamma-GT). Particular attention was given to the addiction behavior before and after tumor therapy (recorded at least 1 year after successful tumor treatment).

RESULTS

At the time of diagnosis, 83.1% regularly drank alcohol (71.9% reported drinking over 40 g/ 20 g of alcohol per day). Another 17.9% stopped drinking after therapy. Of the alcoholics 59.8% had been exposed to a daily consumption level above the threshold amount for more than 20 years. Some 70% of the patients reported that they exclusively drank beer. Tobacco consumption came from cigarette smoking 92.7% and 89.7% reported that they smoked before therapy--after therapy only 37.8% smoked. Carcinomas of the floor of the mouth indicated a prevalence toward alcohol and nicotine abuse. Of the patients with a T3 and T4 carcinoma 84% had daily alcohol consumption levels over the threshold value stated above. None of the 105 patients underwent specific alcohol treatment therapy.

CONCLUSION

In light of the high prevalence of carcinomas of the oral cavity in patients with alcohol and nicotine addiction, mandatory withdrawal therapy should be offered in the form of postoperative treatment to prevent recurrence or the development of second primary tumors, as well as to improve the quality of life and encourage social rehabilitation. Before further treatment, for example, with retinoids, a successful withdrawal treatment should be completed.

[Immunocytochemical venous blood studies in patients with manifest oral cavity carcinomas, oral precancerous conditions, benign tumors and in chronic alcoholic patients]

In a prospective pilot study we investigated the percentage of immunocompetent cells in the peripheral blood in 146 patients (lymphocytes, leucocytes, monocytes, T cells, B cells, NK cells, T-helper cells, T-suppressor cells, ratio T-helper/T-suppressor cells, activated T cells HLA-DR) by flow cytometry. The immunologic parameters were derived from patients with oral and oropharyngeal squamous cell carcinomas, precancerous lesions and benign tumours and from a group of heavy smokers and alcoholics. Carcinoma patients (n = 46) were compared with risk groups and a reference group consisting of patients with inflammatory disease. Within the collective of carcinoma patients we measured the immune status before and after chemo-, radio- and operative therapy. We also analysed the immune parameters in relation to clinical and histomorphological parameters (TNM status, grading). The univariate analysis of monocytes showed significant relationships between on the one hand carcinoma patients and on the other alcoholics and those with benign tumours and precancerous lesions. In precancerous lesions NK cells were significantly increased compared with alcoholics and the reference group. A significant decrease in B cells in carcinoma patients may show incipient insufficiency of the humoral immunity. The immune parameters showed a different reaction depending on therapy. After irradiation we found a significant increase of T-suppressor cytotoxic cells and decreases in B and T-helper cells. Chemotherapy showed an increase in T and T-helper cells and a decrease in B cells. Surgical therapy alone yielded an increase in B cells. The comparison of all pre- and posttherapeutic parameters showed significant changes only in activated T cells HLA-DR. We found no correlation between prognostic clinico-pathological factors and immune parameters. No changes were found in a multivariate analysis.

Coping in the Clinic: Effects of Clinically Elevated Anxiety on Dynamic Neurophysiological Mechanisms of Escape/Avoidance Preparation

BACKGROUND

Treatments for anxiety and related disorders target exaggerated escape/avoidance as a core feature, but current methods fail to improve escape/avoidance habits for many treatment-seeking individuals. To support developing tools that increase treatment efficacy by targeting mechanisms more directly, the current work examined potential distinctions in the neurophysiologies of escape and avoidance and tested how clinical anxiety affects these neurophysiologies.

METHODS

Twenty-five treatment-seeking individuals with varied principal diagnoses (e.g., generalized anxiety disorder, posttraumatic stress disorder) and 20 non-treatment-seeking control subjects participated. In the study task, approximately 5.25-second cues predicted aversive images that could be avoided (blocked by a button press before image onset), escaped (ended by a button press after image onset), or not controlled. To examine neural processing and defensive response modulation, anticipatory event-related potentials were derived, and startle reflexes were probed throughout each cue.

RESULTS

Multidimensional profiles were observed such that 1) anticipatory event-related potential enhancement was only reliable during avoidance preparation, and event-related potentials potentially reflected perceived/instrumental control; and 2) startle reflexes were inhibited during avoidance preparation, relatively enhanced during escape preparation, and further enhanced during uncontrollable anticipation, thus potentially reflecting fear-related activation. Treatment-seeking status, then, did not affect cortical processing, but it did moderate context-dependent fear (if individuals with severe depression were excluded) such that treatment-seeking individuals without depression showed exaggerated startle during escape, but not avoidance, preparation.

CONCLUSIONS

Data suggest a specific effect of anxiety on fear system activation during preparation to escape aversion. This effect warrants further investigation as a precision target for interventions that directly modulate the specific underlying neural circuitry.

A-170 Cognitive Functioning and Default Mode Network as Predictors of Smoking Severity in Adults

Objective: Smoking is a leading cause of avoidable death, with the best cessation treatments yielding only 10-30% abstinence. Limited neurocognitive research is available on the best predictor of cessation: addiction severity. We investigated whether smoking severity is associated with stronger resting functional connectivity and cognitive functioning.

Method: A community sample of 33 adult smokers (mean age=40.77, 72.73% female, 27.27% Black, &gt;10 cigarettes per day [CPD]) completed 8-minutes of resting state functional MRI and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Default network (DN) functional connectivity was conducted using four seed/target regions. RBANS total score was operationalized as overall cognitive function. Smoking severity was operationalized as CPD.

Results: Mean RBANS scores were in the average range (mean=89.76, SD=11.68) and predicted CPD (mean=20.14, SD=9.33), accounting for 20.30% of the variance (see Table). Associations between RBANS and CPD were significantly moderated by mean target region synchrony with three of four seed regions: posterior cingulate cortex (PCC), left posterior precuneus (LPP), and right posterior precuneus (RPP). Medial prefrontal cortex (MPFC) synchrony did not add to the prediction. Repeating these regressions, controlling for age, yielded the same pattern. The three DN seeds continued to yield mean target region effects that exhibited strong interactions with the RBANS to predict severity (see Table).

Conclusions: DN synchrony moderates the association between cognitive function and smoking severity, such that the negative relationship between overall cognitive functioning and smoking severity is only present for those with lower levels of DN synchrony. These markers may improve understanding of neurocognitive mechanisms of smoking severity.

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A-125 Sex Moderates the Positive Effects of Sleep Schedule Consistency on Cognitive Function

Objective: Negative effects of reduced sleep duration and consistency on cognition are well-known. It is also well-known that both decline with age. While emerging research finds that sex interacts with sleep duration, less is known about whether sex interacts with sleep schedule consistency to predict cognitive performance. We hypothesized that reduced sleep consistency would negatively impact cognitive performance and that women would be less affected by inconsistent sleep based on suggested protective effects of brain organization in sleep-deprived women (Corsi-Carbrera et al., 2003).

Methods: Participants (N = 77, 96.3% White) were selected from a parent study of community-dwelling older adults. Inclusion criteria: complete demographic data, Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) index scores, and self-reported sleep data. The sample was majority female and well-educated.

Results: RBANS performance and sleep measures were within normal limits (see Table). There was a significant main effect of sleep consistency across all RBANS scores, controlling age, education, and sleep duration. There were significant main effects of sex on Immediate Memory, Attention, and Total score. Interactions between sleep consistency and sex were significant for Immediate Memory, Delayed Memory, and Total score.

Conclusions: Sleep consistency is associated with better cognitive performance across domains. Women perform better than men globally and in domains of immediate memory and attention, regardless of consistency. Women who sleep consistently are most likely to exhibit better memory and global cognitive function. Findings extend sleep duration effects on cognitive function to variability and suggest consistency may benefit women more than men.

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Accelerated iTBS-Induced changes in resting-state functional connectivity correspond with cognitive improvement in amnestic MCI

BACKGROUND

Published results of our Phase I safety and feasibility trial of accelerated intermittent theta burst stimulation (a-iTBS) in mild cognitive impairment (MCI) due to Alzheimer's disease showed a large effect-size improvement in cognition.

OBJECTIVE

Further demonstrate target engagement by identifying whether changes in local and network-level functional connectivity relate to the observed cognitive improvement.

METHODS

Eighteen patients with MCI received 3-day a-iTBS (8 sessions/day) to the left dorsolateral prefrontal cortex at Beam F3 (14,400 total pulses) and completed MRI and cognitive testing at pre- and post-treatment. Based on electric field models, we selected 3 stimulated target regions of interest (ROIs) which belonged to the frontoparietal (FPN), default mode (DMN), and ventral attention (VAT) networks (3 target networks). Metrics of resting-state functional connectivity were computed at the ROI level (within-network degree: number of connections) and network level (segregation: strength of connectivity within-network relative to other networks). We correlated changes in cognition and connectivity of the target ROIs and networks; off-target ROI (primary visual) and networks served as negative controls.

RESULTS

Improvements in cognition were associated with connectivity changes in the target ROIs and networks, but not in off-target negative controls. Positive associations were observed for degree of the l-DMN and segregation of target networks overall, with significant effects for DMN and VAT.

CONCLUSION

Cognitive improvement following a-iTBS in MCI may be attributable to local and network-level reconfigurations in functional connectivity. These findings will inform larger trials designed to further evaluate the neural mechanisms of a-iTBS for cognition in MCI.

[The primary isolated ovarian abscess. Clinical and bacteriological observations and a new pathogenetic hypothesis (author's transl)]

42 of 86 patients with suppurated ovaries had primary isolated ovarian abscesses (PIOA), 44 secondary tubo-ovarian abscesses (STOA). Parts of ectopic endometrium in the abscess wall could be identified by serial sections in 23 PIOA. With Berlin-blue-staining was a special phenomenon in 28 of 42 PIOA demonstrated: a basal layer of hemosiderophages underlying the abscess membrane. Thus in 36 of 42 PIOA the histogenesis out of cystic ovarian endometriosis or other pathologic ovarian hematomas is assured. The PIOA is a typical major complication of ovarian hematomas, especially in cases of ovarian endometriosis caused by vaginal aplasia (gynatresia). Concomitant salpingitis in PIOA is therefore often better explained as secondary descending infection from pelveoperitonitis. Before laparotomy it is extremely difficult to diagnose PIOA on a clinical basis only. More than laboratory data helps this special consideration if an inflammatory adnexal mass could be or not the result of an ascending infection and if an ovarian endometriosis could exist. Besides the abscesses out of cystic ovarian endometriosis PIOA were observed after hysterectomies and complicated appendectomies possible due to the infection of traumatic ovarian hematomas. The only curative therapy for PIOA is surgery--as soon as possible. Antibiotics are poorly helpful. However the inefficacy of antibiotics usually gives the final indication for laparotomy. Knowing the usual etiology of PIOA out of pathologic (endometriotic) ovarian hematomas we have new guidelines in other clinical problems also: Thus every ovarian endometriosis has to be cured--hormonally or surgically; evacuation of endometriotic cysts during pelvic endoscopy is not a sufficient therapy, for the endometrium would be left in the ovary. During operations provocation of traumatic hematomas of the adnexa should be avoided.