Pilocytic astrocytoma of the optic nerve with intracystic hemorrhage in an adult: illustrative case.

BACKGROUND: Optic pathway gliomas are uncommon, accounting for 3-5% of childhood brain tumors, and are mostly classified as pilocytic astrocytomas (PAs). PAs of the optic nerve are particularly rare in adults. OBSERVATIONS: The authors presented the case of PA of the left optic nerve in a 49-year-old woman along with detailed pathological and molecular analyses and sequential magnetic resonance imaging. The tumor had progressed during 5 years of follow-up along with cyst formation and intracystic hemorrhage; it had a thick capsule and contained xanthochromic fluid. The boundary between tumor and optic nerve was unclear. B-type Raf kinase (BRAF) V600E point mutations or translocations, IDH1-R132H mutations, loss of alpha-thalassemia/mental retardation X-linked, and 1p/19q codeletion were negative. LESSONS: BRAF alterations in pediatric PAs of the optic nerve are less frequent than those observed in PAs in other lesions; the same molecular pattern was observed in the adult case, without changes in BRAF. Surgical management should be indicated only in cases with severely impaired vision or disfigurement because there is no clear border between the tumor and optic nerve. Further discussion is needed to optimize the treatment for adult optic pathway gliomas, including radiotherapy, chemotherapy, and molecular-targeted therapies, in addition to surgical intervention.

A Case of Cerebral Tumor Embolism from Extracardiac Lung Cancer Treated by Mechanical Thrombectomy.

Cerebral tumor embolism is a rare cause of acute ischemic stroke, and extracardiac carcinoma is an extremely rare cause. A 34-year-old man who had been diagnosed with lung cancer developed right hemiparesis and aphasia, with the National Institutes of Health Stroke Scale (NIHSS) score of 17. Magnetic resonance imaging (MRI) showed early ischemic change in the insular cortex and frontotemporal lobe and left internal carotid artery (ICA) terminal occlusion was confirmed by magnetic resonance angiogram (MRA). Mechanical thrombectomy (MT) with contact aspiration by a Penumbra ACE 68, followed by combined technique with a stent retriever was performed, and a soft, fragile embolus was retrieved. Finally, good recanalization was achieved (Thrombolysis in Cerebral Infarction [TICI] scale 2b), and on the next day, the right hemiparesis and aphasia were improved. However, the patient's general condition gradually worsened, and 43 days after thrombectomy, he died from respiratory failure. The retrieved embolus was examined pathologically and diagnosed as mucoepidermoid carcinoma of the same type as his lung cancer. Chest computed tomography (CT) showed that tumor invaded the right pulmonary vein and left atrium; these findings suggested that a piece of the tumor in the left atrium flowed into the left ICA and caused the acute ischemic stroke.

Longitudinal Speech Change After Subthalamic Nucleus Deep Brain Stimulation in Parkinson's Disease Patients: A 2-Year Prospective Study.

BACKGROUND: Speech disorders are among the most common adverse effects after subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson's disease (PD) patients. However, longitudinal speech changes after STN-DBS are not fully understood. OBJECTIVE: We performed a two-year prospective study on PD patients who underwent STN-DBS and analyzed changes in speech function to clarify factors predicting for speech deterioration. METHODS: Twenty-five PD patients were assessed before and up to two years after STN implantation. Speech function was evaluated in the on-stimulation condition and 30 min after stimulation cessation using auditory-perceptual assessment. Patients who experienced overall worsening in speech intelligibility or naturalness ≥1 point during follow-up were classified into a deteriorated group (n = 16), with the remaining subjects being classified into a stable group (n = 9). Cognitive and motor functions were also assessed. RESULTS: The stable group had significantly better values of low volume, monoloudness, and asthenic voice subscores of the auditory-perceptual assessment in the on-stimulation condition compared with the off-stimulation condition. Imprecise consonants, excess loudness variation, and strained voice subscores were improved via cessation of stimulation in both groups. Before surgery, the deteriorated group had significantly lower scores in the Stroop Color-Word Test and Digit Span compared to the stable group. CONCLUSIONS: During follow-up, some subscores showed significant worsening in the on-stimulation condition in both groups. However, beneficial effects of STN-DBS on speech appeared to counterbalance negative effects of STN-DBS on speech function only in the stable group. Worse cognitive function may be a potential predictor for speech deterioration after STN-DBS in PD patients.

Predictive Factors Associated with Pain Relief of Spinal Cord Stimulation for Central Post-stroke Pain.

The efficacy and predictive factors associated with successful spinal cord stimulation (SCS) for central post-stroke pain (CPSP) have yet to be definitively established. Thus, this study evaluated the rates of pain relief found after more than 12 months and the predictive factors associated with the success of SCS for CPSP. The degree of pain after SCS in 18 patients with CPSP was assessed using the Visual Analog Scale preoperatively, at 1, 6 and 12 months after surgery, and at the time of the last follow-up. After calculating the percentage of pain relief (PPR), patients were separated into two groups. The first group exhibited continuing PPR ≥30% at more than 12 months (effect group) while the second group exhibited successful/unsuccessful trials followed by decreasing PPR <30% within 12 months (no effect group). Pain relief for more than 12 months was achieved in eight out of 18 (44.4%) patients during the 67.3 ± 35.5 month follow-up period. Statistically significant differences were found for both the age and stroke location during comparisons of the preoperative characteristics between the two groups. There was a significantly younger mean age for the effect versus the no effect group. Patients with stoke in non-thalamus were significantly enriched in effect group compared with those with stoke in thalamus. Multivariable analysis using these two factors found no statistical differences, suggesting that these two factors might possibly exhibit the same behaviors for the SCS effect. These results suggest that SCS may be able to provide pain relief in young, non-thalamus stroke patients with CPSP.

Long-term Effect and Predictive Factors of Motor Cortex and Spinal Cord Stimulation for Chronic Neuropathic Pain.

The long-term effects of motor cortex stimulation (MCS) and spinal cord stimulation (SCS) remain unknown. To identify the long-term effects after MCS or SCS and determine any associated predictive factors for the outcomes. Fifty patients underwent MCS (n = 15) or SCS (n = 35) for chronic neuropathic pain. The degree of pain was assessed preoperatively, at 1, 6, and 12 months after surgery, and during the time of the last follow-up using Visual Analog Scale (VAS). Percentage of pain relief (PPR) was calculated, with "long-term effect" defined as PPR ≥ 30% and the presence of continued pain relief over 12 months. Outcomes were classified into excellent (PPR ≥ 70%) and good (PPR 30-69%) sub-categories. Long-term effects of MCS and SCS were observed in 53.3% and 57.1% of the patients, respectively. There were no predictive factors of long-term effects identified for any of the various preoperative conditions. However, the VAS at 1 month after surgery was significantly associated with the long-term effects in both MCS and SCS. All patients with an excellent outcome at 1 month after the surgery continued to exhibit these effects. In contrast, patients with the good outcome at 1 month exhibited a significant decrease in the effects at 6 months after surgery. The long-term effects of MCS and SCS were approximately 50% during the more than 8.5 and 3.5 years of follow-up, respectively. The VAS at 1 month after surgery may be a postoperative predictor of the long-term effects for both MCS and SCS.

Early detection of speech and voice disorders in Parkinson's disease patients treated with subthalamic nucleus deep brain stimulation: a 1-year follow-up study.

We previously reported that Parkinson's disease (PD) patients treated with subthalamic nucleus deep brain stimulation (STN-DBS) had distinct phenotypes of speech and voice disorders: hypokinetic dysarthria, stuttering, breathy voice, strained voice, and spastic dysarthria. However, changes over time remain unclear. In the present study, 32 consecutive PD patients were assessed before and up to 1 year after surgery (PD-DBS). Eleven medically treated PD patients were also assessed (PD-Med). Speech, voice, motor, and cognitive functions were evaluated. At baseline, the incidence of hypokinetic dysarthria (63% of PD-DBS vs. 82% of PD-Med), stuttering (50% vs. 45%), breathy voice (66% vs. 73%), and strained voice (3% vs. 9%) was similar between groups. At 1 year, a slight but significant deterioration in speech intelligibility (p < 0.001) and grade of dysphonia (p = 0.001) were observed only in PD-DBS group compared with baseline. During the follow-up, stuttering (9% vs. 18%) and breathy voice (13% vs. 9%) emerged in PD-DBS and PD-Med, but strained voice (28%) and spastic dysarthria (44%) emerged only in PD-DBS. After the stimulation was stopped, strained voice and spastic dysarthria improved in most patients, while stuttering and breathy voice improved in a minority of patients. These findings indicate that the most common DBS-induced speech and voice disorders are strained voice and spastic dysarthria and that STN-DBS potentially aggravates stuttering and breathy voice. An improved understanding of these types of disorders may help detect speech and voice deteriorations during the early phase and lead to appropriate treatments.

Installation of a Neuromate Robot for Stereotactic Surgery: Efforts to Conform to Japanese Specifications and an Approach for Clinical Use-Technical Notes.

The neuromate is a commercially available, image-guided robotic system for use in stereotactic surgery and is employed in Europe and North America. In June 2015, this device was approved in accordance with the Pharmaceutical Affairs Law in Japan. The neuromate can be specified to a wide range of stereotactic procedures in Japan. The stereotactic X-ray system, developed by a Japanese manufacturer, is normally attached to the operating table that provides lateral and anteroposterior images to verify the positions of the recording electrodes. The neuromate is designed to be used with the patient in the supine position on a flat operating table. In Japan, deep brain stimulation surgery is widely performed with the patient's head positioned upward so as to minimize cerebrospinal fluid leakage. The robot base where the patient's head is fixed has an adaptation for a tilted head position (by 25 degrees) to accommodate the operating table at proper angle to hold the patient's upper body. After these modifications, the accuracy of neuromate localization was examined on a computed tomography phantom preparation, showing that the root mean square error was 0.12 ± 0.10 mm. In our hospital, robotic surgeries, such as those using the Da Vinci system or neuromate, require operative guidelines directed by the Medical Risk Management Office and Biomedical Research and Innovation Office. These guidelines include directions for use, procedural manuals, and training courses.

Characteristic laryngoscopic findings in Parkinson's disease patients after subthalamic nucleus deep brain stimulation and its correlation with voice disorder.

Speech and voice disorders are one of the most common adverse effects in Parkinson's disease (PD) patients treated with subthalamic nucleus deep brain stimulation (STN-DBS). However, the pathophysiology of voice and laryngeal dysfunction after STN-DBS remains unclear. We assessed 47 PD patients (22 treated with bilateral STN-DBS (PD-DBS) and 25 treated medically (PD-Med); all patients in both groups matched by age, sex, disease duration, and motor and cognitive function) using the objective and subjective voice assessment batteries (GRBAS scale and Voice Handicap Index), and laryngoscopy. Laryngoscopic examinations revealed that PD-DBS patients showed a significantly higher incidence of incomplete glottal closure (77 vs 48 %; p = 0.039), hyperadduction of the false vocal folds (73 vs 44 %; p = 0.047), anteroposterior hypercompression (50 vs 20 %; p = 0.030) and asymmetrical glottal movement (50 vs 16 %; p = 0.002) than PD-Med patients. On- and off-stimulation assessment revealed that STN-DBS could induce or aggravate incomplete glottal closure, hyperadduction of the false vocal folds, anteroposterior hypercompression, and asymmetrical glottal movement. Incomplete glottal closure and hyperadduction of the false vocal folds significantly correlated with breathiness and strained voice, respectively (r = 0.590 and 0.539). We should adjust patients' DBS settings in consideration of voice and laryngeal functions as well as motor function.

Distinct phenotypes of speech and voice disorders in Parkinson's disease after subthalamic nucleus deep brain stimulation.

OBJECTIVES: To elucidate the phenotypes and pathophysiology of speech and voice disorders in Parkinson's disease (PD) with subthalamic nucleus deep brain stimulation (STN-DBS). METHODS: We conducted a cross-sectional study on 76 PD patients treated with bilateral STN-DBS (PD-DBS) and 33 medically treated PD patients (PD-Med). Speech and voice functions, electrode positions, motor function and cognitive function were comprehensively assessed. Moreover, speech and voice functions were compared between the on-stimulation and off-stimulation conditions in 42 PD-DBS patients. RESULTS: Speech and voice disorders in PD-DBS patients were significantly worse than those in PD-Med patients. Factor analysis and subsequent cluster analysis classified PD-DBS patients into five clusters: relatively good speech and voice function type, 25%; stuttering type, 24%; breathy voice type, 16%; strained voice type, 18%; and spastic dysarthria type, 17%. STN-DBS ameliorated voice tremor or low volume; however, it deteriorated the overall speech intelligibility in most patients. Breathy voice did not show significant changes and stuttering exhibited slight improvement after stopping stimulation. In contrast, patients with strained voice type or spastic dysarthria type showed a greater improvement after stopping stimulation. Spastic dysarthria type patients showed speech disorders similar to spastic dysarthria, which is associated with bilateral upper motor neuron involvement. Strained voice type and spastic dysarthria type appeared to be related to current diffusion to the corticobulbar fibres. CONCLUSIONS: Stuttering and breathy voice can be aggravated by STN-DBS, but are mainly due to aging or PD itself. Strained voice and spastic dysarthria are considered corticobulbar side effects.

[Efficacy of tramadol/acetaminophen medication for central post-stroke pain].

OBJECTIVE: Central post-stroke pain(CPSP)is the most difficult type of central neuropathic pain to control with medical treatment. Opioids are commonly used for chronic neuropathic pain, but their efficacy in treating central neuropathic pain, particularly CPSP, is not clear. Tramadol is an opioid analgesic that, in combination with acetaminophen, has been approved since 2011 for the treatment of non-cancer pain in Japan. In this study we evaluated the efficacy of tramadol/acetaminophen medication for CPSP. METHODS: We retrospectively reviewed nine cases of CPSP that received oral tramadol/acetaminophen medication. All cases received tramadol/acetaminophen medication after first taking pregabalin then antidepressant medication. Pain levels were assessed before tramadol/acetaminophen medication began and one month after a maintenance dose was reached, using a visual analogue scale(VAS)and the McGill pain questionnaire(MPQ). RESULTS: The mean dose of tramadol was 121±61.6 mg/day. Tramadol/acetaminophen medication was effective in reducing pain in seven of nine cases(77.8%). The VAS improved 32.9±13.8% from pre-to post-medication, and the MPQ improved from 15.4±9.1 pre-medication to 8.1±4.7 post-medication(p<0.05). These effects continued 9.3±4.5 months during follow up periods. Side effects were observed in six cases(one severe, one moderate, two mild, two transient), but medication was continued in eight cases. CONCLUSION: Oral tramadol/acetaminophen medication was effective at reducing pain levels in patients with CPSP, and is a medication option for the treatment of CPSP.

Anatomical annotation on vascular structure in volume rendered images.

The precise annotation of vascular structure is desired in computer-assisted systems to help surgeons identify each vessel branch. This paper proposes a method that annotates vessels on volume rendered images by rendering their names on them using a two-pass rendering process. In the first rendering pass, vessel surface models are generated using such properties as centerlines, radii, and running directions. Then the vessel names are drawn on the vessel surfaces. Finally, the vessel name images and the corresponding depth buffer are generated by a virtual camera at the viewpoint. In the second rendering pass, volume rendered images are generated by a ray casting volume rendering algorithm that considers the depth buffer generated in the first rendering pass. After the two-pass rendering is finished, an annotated image is generated by blending the volume rendered image with the surface rendered image. To confirm the effectiveness of our proposed method, we performed a computer-assisted system for the automated annotation of abdominal arteries. The experimental results show that vessel names can be drawn on the corresponding vessel surface in the volume rendered images at a computing cost that is nearly the same as that by volume rendering only. The proposed method has enormous potential to be adopted to annotate the vessels in the 3D medical images in clinical applications, such as image-guided surgery.

Statistical parametric mapping of interictal 123I-iomazenil SPECT in temporal lobe epilepsy surgery.

Brain single photon emission computed tomography (SPECT) for epilepsy is divided into two types (using three radionuclide tracers)-perfusion SPECT (123I-IMP or 99 mTc-ECD), identifying epileptogenic foci by detecting abnormality in regional cerebral blood flow, and 123I-iomazenil SPECT, identifying epileptogenic foci based on distribution of central benzodiazepine receptors. This study aimed to statistically evaluate and compare the SPECT effectiveness for the three tracers. Statistical parametric mapping (SPM) analysis was performed on 30 mesial temporal lobe epilepsy (mTLE) patients. The radionuclide and patient data were categorized as follows: abnormality in the medial temporal lobe on the operated hemisphere (AAA), in the entire temporal lobe on the operated hemisphere (AA), in the dominantly affected temporal lobe on the operated hemisphere (A), in bilateral temporal lobes (B), with no abnormalities in bilateral temporal lobes (C), and with abnormality in the temporal lobe on the nonoperated hemisphere (D). For analyses of (AAA), (AA), and (A), examining the hemisphere containing epileptogenic foci, IMP-SPECT was significantly superior to ECD-SPECT (P<0.05). For (AAA), indicating localization, IMZ-SPECT was significantly superior to the other two (P<0.05). IMP-SPECT was superior for lateralizing and IMZ-SPECT was useful for localizing epileptogenic foci in mTLE patients though the applicability of the results in extratemporal lobe epilepsy is unknown.

[Mood States in outpatients with lesional epilepsy at the neurosurgical clinic and improvement in mood States after lamotrigine addiction].

People with epilepsy have a high incidence of mood disorders that may affect their quality of life. Lamotrigine(LTG)is one of the antiepileptic drugs that are commercially available in Japan these days and its mood-stabilizing qualities were well known. First, 66 outpatients with epilepsy were evaluated for changes in mood states by the Profile of Mood States(POMS)and the Japanese-edition Beck Depression Inventory-Second Edition(BDI-II)on self report. The POMS questionnaire includes 30 items that address six components of mood. At baseline, one third of the outpatients with epilepsy had mood problems compared by POMS health reference. The mean BDI-II baseline score was 14.9±10.1, and one third of these epilepsy patients exhibited moderate or severe depression. Second, in the twelve patients with epilepsy, LTG was added to other antiepileptic drugs, and the POMS and BDI-II were administered at baseline and after addiction to LTG. 4 out of 8(50%)patients with simple partial seizure and 5 out of 8(62.5%)patients after the adjunctive therapy experienced at least a 50% reduction in the number of seizures compared with the self-reported baseline before the adjunctive therapy. The component scores of Depression-Dejection, Anger-Hostility and Confusion-Bewilderment in POMS were statistically improved in these patients completing adjunctive LTG(pared t-test, p<0.05). In these patients, the mean BDI-II baseline score was 25.8±13.1. Following administration of LTG, there was a significant decrease in the mean BDI-II scores(15.0±6.6)between baseline and the end of adjunctive LTG. This study suggests that, in addition to seizure control, LTG may have a mood-stabilizing effect and improve the quality of life in patients with epilepsy.

Surgical bedside master console for neurosurgical robotic system.

PURPOSE: We are currently developing a neurosurgical robotic system that facilitates access to residual tumors and improves brain tumor removal surgical outcomes. The system combines conventional and robotic surgery allowing for a quick conversion between the procedures. This concept requires a new master console that can be positioned at the surgical bedside and be sterilized. METHODS: The master console was developed using new technologies, such as a parallel mechanism and pneumatic sensors. The parallel mechanism is a purely passive 5-DOF (degrees of freedom) joystick based on the author's haptic research. The parallel mechanism enables motion input of conventional brain tumor removal surgery with a compact, intuitive interface that can be used in a conventional surgical environment. In addition, the pneumatic sensors implemented on the mechanism provide an intuitive interface and electrically isolate the tool parts from the mechanism so they can be easily sterilized. RESULTS: The 5-DOF parallel mechanism is compact (17 cm width, 19cm depth, and 15cm height), provides a 505,050 mm and 90° workspace and is highly backdrivable (0.27N of resistance force representing the surgical motion). The evaluation tests revealed that the pneumatic sensors can properly measure the suction strength, grasping force, and hand contact. In addition, an installability test showed that the master console can be used in a conventional surgical environment. CONCLUSION: The proposed master console design was shown to be feasible for operative neurosurgery based on comprehensive testing. This master console is currently being tested for master-slave control with a surgical robotic system.

Preoperative regional cerebral blood flow and postoperative clinical improvement in patients with Parkinson's disease undergoing subthalamic nucleus deep brain stimulation.

Preoperative regional cerebral blood flow (rCBF) was measured in 92 patients with Parkinson's disease (PD) by iodine-123 N-isopropyl-p-iodoamphetamine single-photon emission computed tomography. Quantitative mapping of rCBF was performed using the stereotactic extraction estimation method. The clinical features of the patients were assessed according to the Unified Parkinson Disease Rating Scale (UPDRS). The correlation between rCBF and improvement in the UPDRS score following surgery was examined. rCBF in the fusiform gyrus, superior and inferior parietal gyri, middle occipital gyrus, superior frontal gyrus, and middle temporal gyrus of the Talairach Daemon Level 3 was significantly correlated with UPDRS part II (off stage) and III (on stage) scores (p < 0.05). rCBF in the middle temporal gyrus (p = 0.00147), medial frontal gyrus (p = 0.00713), and cerebellum (p = 0.048) of the Talairach Daemon Level 3 was significantly greater in 47 patients with >60% improvement of UPDRS part III (off stage) score than in 37 patients with 40-60% improvement. The cutoff value of rCBF, which indicated that >40% improvement in the surgical outcome could be expected, was 38.8 ± 6.2 ml/100 g/min in the frontal lobe. This study indicated that rCBF in patients with PD might be related to their clinical features, suggesting that quantitative mapping of rCBF may be useful for predicting surgical outcome.

[Dual lead spinal cord stimulation using octad lead for central post-stroke pain].

Spinal cord stimulation (SCS) has become the preferred option for neurosurgical management of several intractable pains. To evaluate effects of dual lead SCS using two quad leads for central post-stroke pain (CPSP), we retrospectively reviewed eight consecutive patients with CPSP who underwent SCS. Six (75%) of eight patients obtained more than 50% pain relief during test stimulation, and the efficacies continued for about 12 months in five (83%) of six patients. There were no significant complications. SCS is less invasive neurostimulation treatment and provides pain relief for some cases of CPSP.

Efficacy of motor cortex stimulation for intractable central neuropathic pain: comparison of stimulation parameters between post-stroke pain and other central pain.

Motor cortex stimulation (MCS) has now become the preferred option for neurosurgical management of intractable central neuropathic pain such as post-stroke pain and trigeminal neuropathic pain. However, the efficacy of MCS for other central neuropathic pain such as pain resulting from spinal cord or brainstem lesions is unclear. We retrospectively reviewed 11 consecutive patients with intractable central neuropathic pain who underwent MCS in our institution. Eight patients had poststroke pain caused by thalamic hemorrhage (n = 5) or infarction (n = 3) (thalamic group). Two patients had postoperative neuropathic pain caused by spinal cord lesions, and one patient had facial pain caused by a brainstem lesion associated with multiple sclerosis (brainstem-spinal group). Visual analog scale and stimulation parameters were evaluated at 1 and 6 months postoperatively. MCS was effective for six of eight patients in the thalamic group, and all three patients in the brainstem-spinal group. These efficacies continued for 6 months after surgery without significant change in the stimulation parameters compared with the parameters at 1 month in both groups. The mean amplitude at 1 month and frequency at 6 months after surgery were significantly higher in the brainstem-spinal group than the thalamic group, although the patient number was small. MCS is effective for other central neuropathic pain, but higher intensity stimulation parameters may be necessary to gain adequate pain reduction.

Neurosurgical robotic system for brain tumor removal.

PURPOSE: Brain tumor (e.g., glioma) resection surgery, representing the first step for many treatments, is often difficult and time-consuming for neurosurgeons. Thus, intelligent neurosurgical instruments have been developed to improve tumor removal. METHODS: The concept and robotic structure of intelligent neurosurgical instruments were introduced. These instruments consist of a surgical robot, a master device and operating software. The robot incorporates a surgical motion base and tool manipulator, including a volume control suction tool. Open Core Control software was developed for connecting intelligent neurosurgical instruments through a network connection and integrating the instruments into a system. RESULTS: Mechanical evaluation tests on the components and a preliminary system evaluation were performed. A phantom model was fixed on a head frame, and a tumor-removal procedure was successfully performed using prototype intelligent neurosurgical instruments. CONCLUSION: Intelligent neurosurgical instruments are feasible and suitable for on-going evaluation in practical tasks, including in-vivo animal testing.

Development of a real-time tactile sensing system for brain tumor diagnosis.

PURPOSE: Tactile sensing techniques may distinguish tumor from healthy tissue and have potential for intraoperative brain tumor diagnosis. The aim of this study is to develop a biocompatible real-time sensing system to measure tactile information such as softness and smoothness, and its application to brain tumor diagnosis. METHODS: An active tactile sensor is developed using balloon expansion. This compact system provides instantaneous tactile information and has potential for brain tumor diagnosis. Measurements are obtained on soft samples with different stiffness and surface condition with testing of boundary condition influence on thickness and area of the object. Then, measurements on white matter and gray matter of porcine ex vivo brain are done as the first step for brain tumor diagnosis. RESULTS: The sensor can discriminate samples with different stiffness and surface condition subject to influence by boundary conditions. The sensor can evaluate an object relatively under the same boundary conditions but requires enough thickness and area to evaluate absolutely. Measurements on brain show that the sensor can discriminate between white matter and gray matter. CONCLUSIONS: Although the sensor has problems on absolute evaluation, results show that the sensor can evaluate tactile information, and it has potential for brain tumor diagnosis.