Hybrid control algorithm for flexible needle steering: Demonstration in phantom and human cadaver.

Needles are commonly used in the clinic for percutaneous procedures. The outcome of such procedures heavily depends on accurate placement of the needle. There are two main challenges to achieve high accuracy: First, aligning the needle with the targeted lesion, and second, compensating for the deflection of the needle in the tissue. In order to address these challenges, scientists have developed several robotic setups for needle steering. However, the subject is still under research and reliable implementations which can be used in clinical practice are not yet available. In this paper, we have taken some steps in order to bring needle steering closer to practice. A new hybrid control algorithm is developed, which enables us to control a flexible needle by combing base-manipulation and beveled-tip steering methods. A pre-operative path planner is developed which considers the clinical requirements. The proposed method is tested in the lung of a fresh-frozen human cadaver. The work-flow of the experiments are similar to the current clinical practice. Three experimental cases are used to evaluate the proposed steering algorithm. Experimental Case I shows that using the proposed steering algorithm controllability of the needle is increased. In Case II and Case III, the needle is steered in a gelatin phantom and a human cadaver, respectively. The targeting accuracy of 1.35±0.49mm in gelatin phantom and 1.97±0.89mm in cadave is achieved. A feasibility study is performed, in which a fine needle aspiration (FNA) needle is steered in the lungs of a human cadaver under computed tomography guidance. The targeting error for the feasibility study is 2.89±0.22mm. The results suggest that such a robotic system can be beneficial for clinical use and the patient receives less x-ray radiation.

Omental Approach to Functional Recovery After Cerebrovascular Disease.

OBJECTIVE: To review and synthesize the clinical literature regarding risks and benefits of omentum transplantation and transposition surgery in patients with ischemic stroke of other etiology (non-MMD) and Moyamoya disease (MMD), and to evaluate the evidence for biological underpinnings of the presumed physiologic effects of omentum transplantation and transposition on vascularization of brain parenchyma. METHODS: Articles were searched on scientific databases using predefined key terms. Data abstraction was based on the clinical course as reported in the articles. For further analysis, patients were divided into groups according to their diagnosis (MMD or non-MMD). Descriptive statistics were computed for better integration of the results. RESULTS: The final literature review contained 15 articles (11 case series, 4 single case studies) with data on 93 patients (29 non-MMD, 64 MMD). At post-assessment 56% of patients showed substantial gains in functional domains (24% in the non-MMD group, 71% in the MMD group) and 92% demonstrated improvements of cerebral vascularization (55% in the non-MMD group, 98% in the MMD group). Differences in improvement became apparent with regard to the initial symptomatology wherein transient ischemic attacks were related to superior recovery rates and language pathologies showed least improvement. CONCLUSIONS: Surgical revascularization using omental tissue has shown good success rates, particularly for recurrent transient ischemic attacks and prevention of further strokes and should be considered as treatment option for selected patients. Experimental data on the physiologic basis for postoperative improvement delivered convincing evidence for its arteriogenic potential and recent developments in omental stem cell research suggest a role in recovery from long-standing neurological deficits.

Central Somatosensory Networks Respond to a De Novo Innervated Penis: A Proof of Concept in Three Spina Bifida Patients.

INTRODUCTION: Spina bifida (SB) causes low spinal lesions, and patients often have absent genital sensation and a highly impaired sex life. TOMAX (TO MAX-imize sensation, sexuality and quality of life) is a surgical procedure whereby the penis is newly innervated using a sensory nerve originally targeting the inguinal area. Most TOMAX-treated SB patients initially experience penile stimulation as inguinal sensation, but eventually, the perception shifts to penis sensation with erotic feelings. The brain mechanisms mediating this perceptual shift, which are completely unknown, could hold relevance for understanding the brain's role in sexual development. AIM: The aim of this study was to study how a newly perceived penis would be mapped onto the brain after a lifelong disconnection. METHODS: Three TOMAX-treated SB patients participated in a functional magnetic resonance imagery experiment while glans penis, inguinal area, and index finger were stimulated with a paint brush. MAIN OUTCOME MEASURE: Brush stimulation-induced activation of the primary somatosensory cortex (SI) and functional connectivity between SI and remote cerebral regions. RESULTS: Stimulation of the re-innervated side of the glans penis and the intact contralateral inguinal area activated a very similar location on SI. Yet, connectivity analysis identified distinct SI functional networks. In all three subjects, the middle cingulate cortex (MCC) and the parietal operculum-insular cortex (OIC) were functionally connected to SI activity during glans penis stimulation, but not to SI activity induced by inguinal stimulation. CONCLUSIONS: Investigating central somatosensory network activity to a de novo innervated penis in SB patients is feasible and informative. The consistent involvement of MCC and OIC above and beyond the brain network expected on the basis of inguinal stimulation suggests that these areas mediate the novel penis sensation in these patients. The potential role of MCC and OIC in this process is discussed, along with recommendations for further research.

Regional cerebral blood flow changes associated with clitorally induced orgasm in healthy women.

There is a severe lack of knowledge regarding the brain regions involved in human sexual performance in general, and female orgasm in particular. We used [15O]-H2O positron emission tomography to measure regional cerebral blood flow (rCBF) in 12 healthy women during a nonsexual resting state, clitorally induced orgasm, sexual clitoral stimulation (sexual arousal control) and imitation of orgasm (motor output control). Extracerebral markers of sexual performance and orgasm were rectal pressure variability (RPstd) and perceived level of sexual arousal (PSA). Sexual stimulation of the clitoris (compared to rest) significantly increased rCBF in the left secondary and right dorsal primary somatosensory cortex, providing the first account of neocortical processing of sexual clitoral information. In contrast, orgasm was mainly associated with profound rCBF decreases in the neocortex when compared with the control conditions (clitoral stimulation and imitation of orgasm), particularly in the left lateral orbitofrontal cortex, inferior temporal gyrus and anterior temporal pole. Significant positive correlations were found between RPstd and rCBF in the left deep cerebellar nuclei, and between PSA and rCBF in the ventral midbrain and right caudate nucleus. We propose that decreased blood flow in the left lateral orbitofrontal cortex signifies behavioural disinhibition during orgasm in women, and that deactivation of the temporal lobe is directly related to high sexual arousal. In addition, the deep cerebellar nuclei may be involved in orgasm-specific muscle contractions while the involvement of the ventral midbrain and right caudate nucleus suggests a role for dopamine in female sexual arousal and orgasm.