Effects of Transcranial Magnetic Stimulation on Body Perception: No Evidence for Specificity of the Right Temporo-Parietal Junction.

Previous data suggest that the right temporo-parietal junction (rTPJ) may have a specific role in abnormal body perception (ABP), including out-of-body experience. We tested this hypothesis with inhibitory (1 Hz) and excitatory (15 Hz) repetitive transcranial magnetic stimulation (rTMS) of the rTPJ and a control site (CS, 5 cm posterior to the rTPJ along the lateral sulcus direction in Brodmann area 19R) in 35 healthy adults. ABP frequency was higher with 1 Hz than with 15 Hz rTMS but unaffected by the rTMS site (rTPJ/CS). Response to an own-body transformation task were delayed with 1 Hz compared to 15 Hz rTMS but also unaffected by rTMS site. ABP from rTMS at both sites induced electroencephalographic power decrease in all frequencies at left anterior and central cortical sites. Our data suggest that inhibitory rTMS can lead to ABP. However, the rTPJ may not play a specific role in this process.

Case report: Avoidant/restrictive food intake disorder after tonsillectomy.

Background: Avoidant Restrictive Food Intake Disorder (ARFID) is a newly classified eating disorder that requires further understanding of its presentation. There is no previous report of ARFID in a child post-tonsillectomy. ARFID may be a potential negative outcome for children following oropharyngeal surgery. Case presentation: A female child aged 10 years and 2 months presented with ARFID associated with depression, anxiety and nutritional deficiency following tonsillectomy. She had more difficulty in swallowing solids than fluids and had repeated vomiting and spitting food after chewing it. She became dehydrated and malnourished with a BMI of 10.5 and was misdiagnosed with myasthenic gravis. Conclusions: To our knowledge, this is the first case report of ARFID in a child post-tonsillectomy. We discuss the pathophysiology of ARFID, which remains elusive, and recommend psychiatric assessment when evaluating children post operative tonsillectomy.

Less might be more: 1 mA but not 1.5 mA of tDCS improves tactile orientation discrimination.

Background: Transcranial direct current stimulation (tDCS) is a frequently used brain stimulation method; however, studies on tactile perception using tDCS are inconsistent, which might be explained by the variations in endogenous and exogenous parameters that influence tDCS. Objectives: We aimed to investigate the effect of one of these endogenous parameters-the tDCS amplitude-on tactile perception. Methods: We conducted this experiment on 28 undergraduates/graduates aged 18-36 years. In separate sessions, participants received 20 min of 1 mA or 1.5 mA current tDCS in a counterbalanced order. Half of the participants received anodal tDCS of the left SI coupled with cathodal tDCS of the right SI, and this montage was reversed for the other half. Pre- and post-tDCS tactile discrimination performance was assessed using the Grating Orientation Task (GOT). In this task, plastic domes with gratings of different widths cut into their surfaces are placed on the fingertip, and participants have to rate the orientation of the gratings. Results: Linear modeling with amplitude, dome, and session as within factors and montage as between factors revealed the following: significant main effects of grating width, montage, and session and a marginally significant interaction effect of session and amplitude. Posthoc t-tests indicated that performance in GOT improved after 1 mA but not 1.5 mA tDCS independent of the montage pattern of the electrodes. Conclusion: Increasing the stimulation amplitude from 1 mA to 1.5 mA does not facilitate the tDCS effect on GOT performance. On the contrary, the effect seemed more robust for the lower-current amplitude.

Individual differences and creative ideation: neuromodulatory signatures of mindset and response inhibition.

This study addresses the modulatory role of individual mindset in explaining the relationship between response inhibition (RI) and divergent thinking (DT) using transcranial direct current stimulation (tDCS). Forty undergraduate students (22 male and 18 female), aged between 18 and 23 years (average age = 19 years, SD = 1.48), were recruited. Participants received either anodal tDCS of the right IFG coupled with cathodal tDCS of the left IFG (R + L-; N = 19) or the opposite coupling (R-L+; N = 21). We tested DT performance using the alternative uses task (AUT), measuring participants' fluency, originality, and flexibility in the response production, as well as participants' mindsets. Furthermore, we applied a go-no-go task to examine the role of RI before and after stimulating the inferior frontal gyrus (IFG) using tDCS. The results showed that the mindset levels acted as moderators on stimulation conditions and enhanced RI on AUT fluency and flexibility but not originality. Intriguingly, growth mindsets have opposite moderating effects on the change in DT, resulting from the tDCS stimulation of the left and the right IFG, with reduced fluency but enhanced flexibility. Our findings imply that understanding neural modulatory signatures of ideational processes with tDCS strongly benefits from evaluating cognitive status and control functions.

The truth about lying: inhibition of the anterior prefrontal cortex improves deceptive behavior.

Recent neuroimaging studies have indicated a predominant role of the anterior prefrontal cortex (aPFC) in deception and moral cognition, yet the functional contribution of the aPFC to deceptive behavior remains unknown. We hypothesized that modulating the excitability of the aPFC by transcranial direct current stimulation (tDCS) could reveal its functional contribution in generating deceitful responses. Forty-four healthy volunteers participated in a thief role-play in which they were supposed to steal money and then to attend an interrogation with the Guilty Knowledge Test. During the interrogation, participants received cathodal, anodal, or sham tDCS. Remarkably, inhibition of the aPFC by cathodal tDCS did not lead to an impairment of deceptive behavior but rather to a significant improvement. This effect manifested in faster reaction times in telling lies, but not in telling the truth, a decrease in sympathetic skin-conductance response and feelings of guilt while deceiving the interrogator and a significantly higher lying quotient reflecting skillful lying. Increasing the excitability of the aPFC by anodal tDCS did not affect deceptive behavior, confirming the specificity of the stimulation polarity. These findings give causal support to recent correlative data obtained by functional magnetic resonance imaging studies indicating a pivotal role of the aPFC in deception.

Case Report: Catatonia Associated With Post-traumatic Stress Disorder.

We report here about a 12-year-old female patient who had two life-threatening accidents that led to post-traumatic stress disorder associated with catatonia. She had closed eyes, had urinary and fecal incontinence, and had been in an abnormal position for one and half month. Moreover, she had complications such as dehydration, malunion of the fractured arm, and deformities in hand and foot. After detailed psychiatric examination, neurological assessment, and laboratory investigation, the patient received successful treatment in the form of benzodiazepine injections, intravenous fluid, oral antidepressants, and six sessions of electroconvulsive therapy (ECT). We discuss the pathophysiology of catatonia, which remains elusive, and recommend evaluating catatonic children for any possible trauma during psychiatry assessment.

A double-blind randomized clinical trial of high frequency rTMS over the DLPFC on nicotine dependence, anxiety and depression.

High frequency repetitive transcranial magnetic stimulation (HF-rTMS) over the left dorsolateral prefrontal cortex (L-DLPFC) is a widely applied treatment protocol for chronic smoking and major depressive disorder. However, no previous study has measured the effects of rTMS on both nicotine consumption and anxiety/depression in the same volunteers despite the relationship between them. The aim of this work was to evaluate the efficacy of 10 daily sessions of HF-rTMS over the L-DLPFC in chronic cigarette smokers' addiction and investigate the possible beneficial effects of this treatment procedure on symptoms of depression and anxiety in the same subjects. The study included 40 treatment-seeking nicotine-dependent cigarette smokers. Onset/duration of smoking, number of cigarettes/day, Fagerstrom Test of Nicotine Dependence (FTND), Tobacco Craving Questionnaire-Short Form (TCQ-SF), Hamilton depression and anxiety scales (HAM-D and HAM-A) were recorded. Participants were randomly assigned to the active or the sham treatment group. Those in the active group received 10 trains of 20 Hz stimulation, at 80% of the resting motor threshold (rMT) for 10 consecutive working days over L-DLPFC. Participants were reassessed immediately after treatment, and then 3 months later using all rating scales. There were no differences between active and sham groups at baseline. The cigarette consumption/day, and scores on FTND, and TCQ decreased significantly in both groups (p = 0.0001 for each) immediately after treatment. However, improvement persisted to 3 months in the active group but not in the sham group. Moreover, there was a significant reduction in HAM-D and HAM-A scores immediately after treatment in the active but not the sham group. Subjects with a longer history of smoking had a lower percent improvement in FTND (p = 0.005). Our findings revealed that HF-rTMS over L-DLPCF for 10 days reduced cigarette consumption, craving, dependence, and improved associated symptoms of anxiety and depression.ClinicalTrials.gov Identifier: NCT03264755 registered at 29/08/2017.

Case Report: Guillain-Barré Syndrome Associated With COVID-19.

Guillain-Barré syndrome (GBS) is a potentially fatal, immune-mediated disease of the peripheral nervous system that is usually triggered by infection. Only a small number of cases of GBS associated with COVID-19 infection have been published. We report here five patients with GBS admitted to the Neurology, Psychiatry, and Neurosurgery Hospital, Assiut University/Egypt from July 1 to November 20, 2020. Three of the five patients were positive for SARS-CoV-2 following polymerase chain reaction (PCR) of nasopharyngeal swabs on day of admission and another one had a high level of IgM and IgG; all had bilateral ground-glass opacities with consolidation on CT chest scan (GGO) and lymphopenia. All patients presented with two or more of the following: fever, cough, malaise, vomiting, and diarrhea with variable duration. However, there were some peculiarities in the clinical presentation. First, there were only 3 to 14 days between the onset of COVID-19 symptoms and the first symptoms of GBS, which developed into flaccid areflexic quadriplegia with glove and stocking hypoesthesia. The second peculiarity was that three of the cases had cranial nerve involvement, suggesting that there may be a high incidence of cranial involvement in SARS-CoV-2-associated GBS. Other peculiarities occurred. Case 2 presented with a cerebellar hemorrhage before symptoms of COVID-19 and had a cardiac attack with elevated cardiac enzymes following onset of GBS symptoms. Case 5 was also unusual in that the onset began with bilateral facial palsy, which preceded the sensory and motor manifestations of GBS (descending course). Neurophysiological studies showed evidence of sensorimotor demyelinating polyradiculoneuropathy, suggesting acute inflammatory polyneuropathy (AIDP) in all patients. Three patients received plasmapheresis. All of them had either full recovery or partial recovery. Possible pathophysiological links between GBS and COVID-19 are discussed.

Effects of tDCS on Language Recovery in Post-Stroke Aphasia: A Pilot Study Investigating Clinical Parameters and White Matter Change with Diffusion Imaging.

Objectives: In this pilot study we investigated the effects of transcranial direct current stimulation (tDCS) on language recovery in the subacute stage of post-stroke aphasia using clinical parameters and diffusion imaging with constrained spherical deconvolution-based tractography. Methods: The study included 21 patients with subacute post-stroke aphasia. Patients were randomly classified into two groups with a ratio of 2:1 to receive real tDCS or sham tDCS as placebo control. Patients received 10 sessions (5/week) bi-hemispheric tDCS treatments over the left affected Broca's area (anodal electrode) and over the right unaffected Broca's area (cathodal stimulation). Aphasia score was assessed clinically using the language section of the Hemispheric Stroke Scale (HSS) before and after treatment sessions. Diffusion imaging and tractography were performed for seven patients of the real group, both before and after the 10th session. Dissection of language-related white matter tracts was achieved, and diffusion measures were extracted. A paired Student's t-test was used to compare the clinical recovery and diffusion measures of the dissected tracts both pre- and post- treatment. The partial correlation between changes in diffusion measures and the language improvements was calculated. Results: At baseline assessment, there were no significant differences between groups in demographic and clinical HSS language score. No significant clinical recovery in HSS was evident in the sham group. However, significant improvements in the different components of HSS were only observed in patients receiving real tDCS. Associated significant increase in the fractional anisotropy of the right uncinate fasciculus and a significant reduction in the mean diffusivity of the right frontal aslant tract were reported. A significant positive correlation was found between the changes in the right uncinate fasciculus and fluency improvement. Conclusions: Aphasia recovery after bi-hemispheric transcranial direct current stimulation was associated with contralesional right-sided white matter changes at the subacute stage. These changes probably reflect neuroplasticity that could contribute to the recovery. Both the right uncinate fasciculus and right frontal aslant tract seem to be involved in aphasia recovery.

Effects of tDCS on Tactile Perception Depend on Tactile Expertise in Both Musicians and Non-Musicians.

Brain plasticity in the somatosensory cortex and tactile performance can be facilitated by brain stimulation. Here, we investigated the effects of transcranial direct current stimulation (tDCS) on tactile perception in musicians and non-musicians to elucidate how tDCS-effects might depend on tactile expertise. On three separate days, 17 semi-professional musicians (e.g., piano or violin players) and 16 non-musicians aged 18-27 years received 15 min of 1 mA anodal (a-tDCS), cathodal (c-tDCS) or sham tDCS in a pseudorandomized design. Pre and post tDCS, tactile sensitivity (Touch Detection Task; TDT) and discrimination performance (Grating Orientation Task; GOT) were assessed. For further analysis, the weekly hours of instrument-playing and computer-typing were combined into a "tactile experience" variable. For GOT, but not TDT, a significant group effect at baseline was revealed with musicians performing better than non-musicians. TDT thresholds were significantly reduced after a-tDCS but not c-tDCS or sham stimulation. While both musicians' and non-musicians' performance improved after anodal stimulation, neither musical nor tactile expertise was directly associated with the magnitude of this improvement. Low performers in TDT with high tactile experience profited most from a-tDCS. We conclude that tactile expertise may facilitate somatosensory cortical plasticity and tactile learning in low performers.

Case Report: Acute Spinal Cord Myelopathy in Patients With COVID-19.

COVID-19 is typically associated with fever and severe respiratory symptoms including dry cough and dyspnea. However, COVID-19 may also affect both central and peripheral nervous systems. To date, the incidence rate of spinal cord involvement in COVID-19 is not known and the pathogenesis is still not fully understood. We report here two female patients admitted to Assiut University Hospitals/Egypt during the period from first of July to August 10, 2020. Both presented with a positive SARS-CoV-2 polymerase chain reaction (PCR) nasopharyngeal swab, elevated serum d-dimer and ferritin levels, and bilateral ground glass appearance in a CT chest scan. The first was a 60-year-old female with acute onset of flaccid paraplegia 10 days after flu-like symptoms, in whom MRI revealed transverse myelitis. The second was a 21-year-old female with symptoms of acute quadriplegia, fever, headache, and anosmia in whom an MRI scan revealed long cervico-thoracic myelopathy. Anterior spinal artery occlusion and possibly transverse myelitis were considered as differential diagnosis of long segment myelopathy.

Effects of transcranial direct current stimulation of left and right inferior frontal gyrus on creative divergent thinking are moderated by changes in inhibition control.

Divergent thinking (DT) as one component of creativity is the ability to search for multiple solutions to a single problem and is reliably tested with the Alternative Uses Task (AUT). DT depends on activity in the inferior frontal gyrus (IFG), a prefrontal region that has also been associated with inhibitory control (IC). Experimentally manipulating IC through transcranial direct current stimulation (tDCS) led to alterations in DT. Here, we aimed at further examining such potential mediating effects of IC on DT (measured as flexibility, fluency, and originality in the AUT) by modulating IC tDCS. Participants received either cathodal tDCS (c-tDCS) of the left IFG coupled with anodal tDCS (a-tDCS) of the right IFG (L-R + ; N = 19), or the opposite treatment (L + R-; N = 21). We hypothesized that L + R- stimulation would enhance IC assessed with the Go NoGo task (GNGT), and that facilitated IC would result in lower creativity scores. The reversed stimulation arrangement (i.e., L- R +) should result in higher creativity scores. We found that tDCS only affected the originality component of the AUT but not flexibility or fluency. We also found no effects on IC, and thus, the mediation effect of IC could not be confirmed. However, we observed a moderation effect: inhibition of left and facilitation of right IFG (L-R +) resulted in enhanced flexibility and originality scores, only when IC performance was also improved. We conclude that inducing a right-to-left gradient in IFG activity by tDCS is efficient in enhancing DT, but only under conditions where tDCS is sufficient to alter IC performance as well.

Correction to: Effects of transcranial direct current stimulation of left and right inferior frontal gyrus on creative divergent thinking are moderated by changes in inhibition control.

The caption of Fig. 2 is incorrect.

Modulating dream experience: Noninvasive brain stimulation over the sensorimotor cortex reduces dream movement.

Recently, cortical correlates of specific dream contents have been reported, such as the activation of the sensorimotor cortex during dreamed hand clenching. Yet, despite a close resemblance of such activation patterns to those seen during the corresponding wakeful behaviour, the causal mechanisms underlying specific dream contents remain largely elusive. Here, we aimed to investigate the causal role of the sensorimotor cortex in generating movement and bodily sensations during REM sleep dreaming. Following bihemispheric transcranial direct current stimulation (tDCS) or sham stimulation, guided by functional mapping of the primary motor cortex, naive participants were awakened from REM sleep and responded to a questionnaire on bodily sensations in dreams. Electromyographic (EMG) and electroencephalographic (EEG) recordings were used to quantify physiological changes during the preceding REM period. We found that tDCS, compared to sham stimulation, significantly decreased reports of dream movement, especially of repetitive actions. Other types of bodily experiences, such as tactile or vestibular sensations, were not affected by tDCS, confirming the specificity of stimulation effects to movement sensations. In addition, tDCS reduced EEG interhemispheric coherence in parietal areas and affected the phasic EMG correlation between both arms. These findings show that a complex temporal reorganization of the motor network co-occurred with the reduction of dream movement, revealing a link between central and peripheral motor processes and movement sensations of the dream self. tDCS over the sensorimotor cortex interferes with dream movement during REM sleep, which is consistent with a causal contribution to dream experience and has broader implications for understanding the neural basis of self-experience in dreams.

Split cord malformation in adults: Literature review and classification.

The objective of this study was to summarize the available literature describing the presentation, diagnostic evaluation, and management for adults with Type 1 and Type 2 split spinal cord malformations. A review of the literature was performed using the CINAHL, PubMed, Embase, and Web of Science database, alongside all associated bibliographies, to include studies describing Type 1 and Type 2 split cord malformations diagnosed in patients above the age of 18. All relevant studies of split cord malformations were included, regardless of the year published and terminology used to describe the dysraphism. Clinical case series (≥ 2 patients), cohort studies, and review articles comprising adult patients with radiographically diagnosed diastematomyelia, diplomyelia, or dimyelia were included (Class of Evidence I-IV). A total of 17 unique articles, describing 146 unique adult spinal cord malformation subjects, were included. The most common associated condition was tethered cord syndrome (59.8 %). Operative management for symptomatic split cord malformation was performed in 72.3 % of cases. For those with preoperative neurologic deficits, operative management resulted in symptomatic improvement in 96.6 %, compared to 0 % conservative management (p < 0.05). For those with pain alone, operative management resulted in improvement of 91.1 %, compared to 12.5 % conservative management (p < 0.05). To date, this is the only literature review to include all split cord malformations (SCM Types I and II) presenting in adulthood, with clinical characteristics, associated conditions, and long-term treatment outcomes.

Prevalence of anemia and its relationship with neurological status in patients undergoing surgery for degenerative cervical myelopathy and radiculopathy: A retrospective study of 2 spine centers.

Both degenerative cervical myelopathy (DCM) and anemia are common among older patients, however insufficient data exists evaluating their co-occurrence and the influence of anemia on baseline neurological status. To address this, we examined a retrospective multicenter series of patients treated for DCM or radiculopathy. Myelopathy was graded using the Nurick scale. Established criteria for diagnosing abnormalities were used to identify blood abnormalities, including macrocytic and microcytic anemia. Multivariable regression was used to determine the impact of hematological anomalies on Nurick grades. In our analysis, we included 725 patients (age of 57.1 ± 11.7), of whom 398 presented with myelopathy and 327 presented with radiculopathy alone. Twenty six percent of all patients were anemic at baseline and the mean preoperative Nurick grade across all patients was 2.09 ± 1.29; mean Nurick grade amongst those with DCM was 2.98 ± 1.12. Compared to those with myelopathy, patients with radiculopathy were significantly younger (53.8 ± 11.0 vs 59.8 ± 11.6, p < 0.001) and less likely to be anemic (16.8% vs 33.7%, p < 0.0001). Nurick grading was significantly higher in myelopathy patients with anemia (3.13 ± 1.19 vs 2.91 ± 1.07, p = 0.05) and macrocytic anemia (4.00 ± 1.41 vs 2.97 ± 1.11, p = 0.04). Multivariate regression demonstrated that anemia (p < 0.001), age (p < 0.0001), and posterior surgical approach (p < 0.0001) were related to worse preoperative Nurick grade. In sum, these data suggest that anemia and degenerative cervical spine pathologies commonly co-occur. Anemia, and macrocytic anemia specifically, is associated with poorer neurological status in myelopathic patients. These data suggest anemia may influence baseline neurological status and impact surgical recovery in patients treated for DCM or radiculopathy.

The Link Between Creativity, Cognition, and Creative Drives and Underlying Neural Mechanisms.

Having a creative mind is one of the gateways for achieving fabulous success and remarkable progress in professional, personal and social life. Therefore, a better understanding of the neural correlates and the underlying neural mechanisms related to creative ideation is crucial and valuable. However, the current literature on neural systems and circuits underlying creative cognition, and on how creative drives such as motivation, mood states, and reward could shape our creative mind through the associated neuromodulatory systems [i.e., the dopaminergic (DA), the noradrenergic (NE) and the serotonergic (5-HT) system] seems to be insufficient to explain the creative ideation and production process. One reason might be that the mentioned systems and processes are usually investigated in isolation and independent of each other. Through this review, we aim at advancing the current state of knowledge by providing an integrative view on the interactions between neural systems underlying the creative cognition and the creative drive and associated neuromodulatory systems (see Figure 1).

Dynamic Communications Between GABAA Switch, Local Connectivity, and Synapses During Cortical Development: A Computational Study.

Several factors regulate cortical development, such as changes in local connectivity and the influences of dynamical synapses. In this study, we simulated various factors affecting the regulation of neural network activity during cortical development. Previous studies have shown that during early cortical development, the reversal potential of GABAA shifts from depolarizing to hyperpolarizing. Here we provide the first integrative computational model to simulate the combined effects of these factors in a unified framework (building on our prior work: Khalil et al., 2017a,b). In the current study, we extend our model to monitor firing activity in response to the excitatory action of GABAA. Precisely, we created a Spiking Neural Network model that included certain biophysical parameters for lateral connectivity (distance between adjacent neurons) and nearby local connectivity (complex connections involving those between neuronal groups). We simulated different network scenarios (for immature and mature conditions) based on these biophysical parameters. Then, we implemented two forms of Short-term synaptic plasticity (depression and facilitation). Each form has two distinct kinds according to its synaptic time constant value. Finally, in both sets of networks, we compared firing rate activity responses before and after simulating dynamical synapses. Based on simulation results, we found that the modulation effect of dynamical synapses for evaluating and shaping the firing activity of the neural network is strongly dependent on the physiological state of GABAA. Moreover, the STP mechanism acts differently in every network scenario, mirroring the crucial modulating roles of these critical parameters during cortical development. Clinical implications for pathological alterations of GABAergic signaling in neurological and psychiatric disorders are discussed.

Social decision making in autism: On the impact of mirror neurons, motor control, and imitative behaviors.

The Mirror Neuron System (MNS) plays a crucial role in action perception and imitative behavior, which is suggested to be impaired in Autism Spectrum Disorders (ASDs). In this review, we discuss the plausibility and empirical evidence of a neural interaction between the MNS, action perception, empathy, imitative behavior, and their impact on social decision making in ASDs. To date, there is no consensus regarding a particular theory in ASDs and its underlying mechanisms. Some theories have completely focused on social difficulties, others have emphasized sensory aspects. Based on the current studies, we suggest a multilayer neural network model including the MNS on a first layer and transforming this information to a higher layer network responsible for reasoning. Future studies with ASD participants combining behavioral tasks with neuroimaging methods and transcranial brain stimulation as well as computational modeling can help validate and complement this suggested model. Moreover, we propose applying the behavioral paradigms, and the neurophysiological markers mentioned in this review article for evaluating psychiatric treatment approaches in ASDs. The investigation of modulating effects of different treatment approaches on the neurophysiological markers of the MNS can help find specific subgroups of ASDs patients and support tailored psychiatric interventions.

Pedicle screw accuracy assessment in ExcelsiusGPS® robotic spine surgery: evaluation of deviation from pre-planned trajectory.

BACKGROUND: The ExcelsiusGPS® (Globus Medical, Inc., Audubon, PA) is a next-generation spine surgery robotic system recently approved for use in the United States. The objective of the current study is to assess pedicle screw accuracy and clinical outcomes among two of the first operative cases utilizing the ExcelsiusGPS® robotic system and describe a novel metric to quantify screw deviation. METHODS: Two patients who underwent lumbar fusion at a single institution with the ExcelsiusGPS® surgical robot were included. Pre-operative trajectory planning was performed from an intra-operative CT scan using the O-arm (Medtronic, Inc., Minneapolis, MN). After robotic-assisted screw implantation, a post-operative CT scan was obtained to confirm ideal screw placement and accuracy with the planned trajectory. A novel pedicle screw accuracy algorithm was devised to measure screw tip/tail deviation distance and angular offset on axial and sagittal planes. Screw accuracy was concurrently determined by a blinded neuroradiologist using the traditional Gertzbein-Robbins method. Clinical variables such as symptomatology, operative data, and post-operative follow-up were also collected. RESULTS: Eight pedicle screws were placed in two L4-L5 fusion cases. Mean screw tip deviation was 2.1 mm (range 0.8-5.2 mm), mean tail deviation was 3.2 mm (range 0.9-5.4 mm), and mean angular offset was 2.4 degrees (range 0.7-3.8 degrees). All eight screws were accurately placed based on the Gertzbein-Robbins scale (88% Grade A and 12% Grade B). There were no cases of screw revision or new post-operative deficit. Both patients experienced improvement in Frankel grade and Karnofsky Performance Status (KPS) score by 6 weeks post-op. CONCLUSION: The ExcelsiusGPS® robot allows for precise execution of an intended pre-planned trajectory and accurate screw placement in the first patients to undergo robotic-assisted fusion with this technology.