Robot-assisted stereoelectroencephalography

Robot-assisted stereoelectroencephalography

McGovern et al., performed a retrospective, single-center study in consecutive children with medically refractory epilepsy who were undergoing robot-assisted SEEG. Kaplan-Meier survival analysis was used to calculate the probability of seizure freedom. Both univariate and multivariate methods were used to analyze the preoperative and operative factors associated with seizure freedom.

Fifty-seven children underwent a total of 64 robot-assisted procedures. The patients’ mean age was 12 years, an average of 6.4 antiepileptic drugs (AEDs) per patient had failed prior to implantation, and in 56% of the patients the disease was considered nonlesional. On average, children had 12.4 electrodes placed per implantation, with an implantation time of 9.6 minutes per electrode and a 10-day postoperative stay. SEEG analysis yielded a definable epileptogenic zone in 51 (89%) patients; 42 (74%) patients underwent surgery, half of whom were seizure free at last follow-up, 19.6 months from resection. In a multivariate generalized linear model, resective surgery, older age, and shorter SEEG-related hospital length of stay were associated with seizure freedom. In a Cox proportional hazards model including only the children who underwent resective surgery, older age was the only significant factor associated with seizure freedom. Complications related to bleeding were the major contributors to morbidity. One patient (1.5%) had a symptomatic hemorrhage resulting in a permanent neurological deficit.

McGovern et al., reported one of the largest pediatric-specific SEEG series demonstrating that the modern surgical management of medically refractory epilepsy in children can lead to seizure freedom in many patients, while also highlighting the challenges posed by this difficult patient population 1).

Willems et al., analyzed 18 consecutive patients (mean age: 30.5 years, range: 12-46; 61% female) undergoing invasive presurgical video-EEG monitoring via sEEG electrodes (n = 167 implanted electrodes) over a period of 2.5 years with robot-assisted implantation. There were no neurological deficits reported after implantation or explantation in any of the enrolled patients. Postimplantation imaging showed a minimal subclinical subarachnoid hemorrhage in one patient and further workup revealed a previously unknown factor VII deficiency. No injuries or status epilepticus occurred during video-EEG monitoring. In one patient, a seizure-related asymptomatic cross break of two fixation screws was found and led to revision surgery. Unspecific symptoms like headaches or low-grade fever were present in 10 of 18 (56%) patients during the first days of video-EEG monitoring and were transient. Postexplantation imaging showed asymptomatic and small bleedings close to four electrodes (2.8%).

Overall, sEEG is a safe and well-tolerated procedure. Systematic imaging after implantation and explantation helps to identify clinically silent complications of sEEG. In the literature, complication rates of up to 4.4% in sEEG and in 49.9% of subdural EEG are reported; however, systematic imaging after explantation was not performed throughout the studies, which may have led to underreporting of associated complications 2).


Over a period of 4 years, Serletis et al., prospectively identified 200 patients with refractory epilepsy who collectively underwent 2663 tailored SEEG electrode implantations for invasive intracranial EEG monitoring and extraoperative mapping. The first 122 patients underwent conventional Leksell frame-based SEEG electrode placement; the remaining 78 patients underwent frameless stereotaxy under robotic guidance, following acquisition of a stereotactic ROSA robotic device at the authors’ institution. Electrodes were placed according to a preimplantation hypothesis of the presumed epileptogenic zone, based on a standardized preoperative workup including video-EEG monitoring, MRI, PET, ictal SPECT, and neuropsychological assessment. Demographic features, seizure semiology, number and location of implanted SEEG electrodes, and location of the epileptogenic zone were recorded and analyzed for all patients. For patients undergoing subsequent craniotomy for resection, the type of resection and procedure-related complications were prospectively recorded. These results were analyzed and correlated with pathological diagnosis and postoperative seizure outcomes.

The epileptogenic zone was confirmed by SEEG in 154 patients (77%), of which 134 (87%) underwent subsequent craniotomy for epileptogenic zone resection. Within this cohort, 90 patients had a minimum follow-up of at least 12 months; therein, 61 patients (67.8%) remained seizure free, with an average follow-up period of 2.4 years. The most common pathological diagnosis was focal cortical dysplasia Type I (55 patients, 61.1%). Per electrode, the surgical complications included wound infection (0.08%), hemorrhagic complications (0.08%), and a transient neurological deficit (0.04%) in a total of 5 patients (2.5%). One patient (0.5%) ultimately died due to intracerebral hematoma directly ensuing from SEEG electrode placement 3).


Four hundred nineteen procedures were performed in the Claudio Munari Centre for Epilepsy and Parkinson Surgery, Niguarda Ca’ Granda Hospital, Milano, Italy with the traditional 2-step surgical workflow, which was modified for the subsequent 81 procedures. The new workflow entailed acquisition of brain 3-dimensional angiography and magnetic resonance imaging in frameless and markerless conditions, advanced multimodal planning, and robot-assisted implantation. Quantitative analysis for in vivo entry point and target point localization error was performed on a sub–data set of 118 procedures (1567 electrodes).

The methodology allowed successful implantation in all cases. Major complication rate was 12 of 500 (2.4%), including 1 death for indirect morbidity. Median entry point localization error was 1.43 mm (interquartile range, 0.91-2.21 mm) with the traditional workflow and 0.78 mm (interquartile range, 0.49-1.08 mm) with the new one (P < 2.2 × 10). Median target point localization errors were 2.69 mm (interquartile range, 1.89-3.67 mm) and 1.77 mm (interquartile range, 1.25-2.51 mm; P < 2.2 × 10), respectively.

SEEG is a safe and accurate procedure for the invasive assessment of the epileptogenic zone. Traditional Talairach methodology, implemented by multimodal planning and robot-assisted surgery, allows direct electrical recording from superficial and deep-seated brain structures, providing essential information in the most complex cases of drug-resistant epilepsy 4).



McGovern RA, Knight EP, Gupta A, Moosa ANV, Wyllie E, Bingaman WE, Gonzalez-Martinez J. Robot-assisted stereoelectroencephalography in children. J Neurosurg Pediatr. 2018 Dec 7;23(3):288-296. doi: 10.3171/2018.7.PEDS18305. PubMed PMID: 30544342.

Willems LM, Reif PS, Spyrantis A, Cattani A, Freiman TM, Seifert V, Wagner M, You SJ, Schubert-Bast S, Bauer S, Klein KM, Rosenow F, Strzelczyk A. Invasive EEG-electrodes in presurgical evaluation of epilepsies: Systematic analysis of implantation-, video-EEG-monitoring- and explantation-related complications, and review of literature. Epilepsy Behav. 2018 Jun 13. pii: S1525-5050(18)30253-1. doi: 10.1016/j.yebeh.2018.05.012. [Epub ahead of print] PubMed PMID: 29907526.

Serletis D, Bulacio J, Bingaman W, Najm I, González-Martínez J. The stereotactic approach for mapping epileptic networks: a prospective study of 200 patients. J Neurosurg. 2014 Nov;121(5):1239-46. doi: 10.3171/2014.7.JNS132306. PubMed PMID: 25148007.

Cardinale F, Cossu M, Castana L, Casaceli G, Schiariti MP, Miserocchi A, Fuschillo D, Moscato A, Caborni C, Arnulfo G, Lo Russo G. Stereoelectroencephalography: surgical methodology, safety, and stereotactic application accuracy in 500 procedures. Neurosurgery. 2013 Mar;72(3):353-66; discussion 366. doi: 10.1227/NEU.0b013e31827d1161. PubMed PMID: 23168681.

End to side anastomosis

End to side anastomosis

End-to-endend-to-side, and side-to-side microvascular anastomoses are the main types of vascular bypass grafting used in microsurgery and neurosurgery.

The end-to-side anastomosis is 1 of the most common anastomosis configurations used in cerebrovascular surgery.

Although several living practice models have been proposed for this technique, few involve purely arterial vessels.

Currently, there has been no animal model available for practicing all three anastomoses in one operation. The aim of a study of Yin et al., was to develop a novel animal modelthat utilizes the rat abdominal aorta (AA), common iliac artery(CIAs), and the median sacral artery (MSA) for practicing these three types of anastomosis.

Eight adult Sprague Dawley rats were anesthetized and then laparotomized. The AA, MSA, and bilateral CIAs were exposed and separated from the surrounding tissues. The length and diameter of each artery were measured. The relatively long segment of the AA without major branches was selected to perform end-to-end anastomosis. One side of the CIAs (or AA) and MSA were used for end-to-side anastomosis. The bilateral CIAs were applied to a side-to-side and another end-to-side anastomosis.

Anatomical dissection of the AA, CIAs, and MSA was successfully performed on eight Sprague-Dawley rats; four arterial-to-arterial anastomoses were possible for each animal. The AA trunk between the left renal artery and right iliolumbar arteries was 15.60 ± 0.76 mm in length, 1.59 ± 0.15 mm in diameter, for an end-to-end anastomosis. The left CIA was 1.06 ± 0.08 mm in diameter, for an end-to-side anastomosis with the right CIA. The MSA was 0.78 ± 0.07 mm in diameter, for another end-to-side anastomosis with the right CIA or AA. After finishing end-to-side anastomosis in the proximal part of bilateral CIAs, the distal portion was juxtaposed for an average length of 5.6 ± 0.25 mm, for a side-to-side anastomosis.

This model can comprehensively and effectively simulate anastomosis used in revascularization procedures and can provide more opportunities for surgical education, which may lead to more routine use in microvascular anastomosis training. 1).

The purpose of a study was to compare 2 arterial models using common carotid arteries (CCAs) and common iliac arteries (CIAs) in rats.

The CIAs and CCAs were exposed in 10 anesthetized rats, and their lengths and diameters were measured. Also, the mobilization extent of each vessel along its contralateral counterpart was measured after each artery had been transected at its proximal exposure point. We also studied the technical advantages and disadvantages of each model for practicing end-to-side anastomosis.

The average diameters of the CCA and CIA were 1.1 and 1.3 mm, respectively. The average extent of mobilization along the contralateral vessel was 13.9 mm and 10.3 mm for CCA and CIA, respectively. The CCA model had the advantages of greater arterial redundancy (allowing completion of both suture lines extraluminally) and a minimal risk of venous injury. The main disadvantage of the CCA model was the risk of cerebral ischemia. The CIA model was not limited by the ischemic time and provided the technical challenge of microsurgical dissection of the common iliac vein from the CIA, although it had limited CIA redundancy.

Both CCA and CIA models could be efficiently used for practicing the end-to-side anastomosis technique. Each model provides the trainee with a specific set of advantages and disadvantages that could help with the optimal selection of the practice model according to trainee’s skill level 2).

Case reports

A dolichoectatic intracranial vessel with multiple fusiform aneurysms on the same vessel segment is rare, and usually managed with a bypass with aneurysm trapping. This video demonstrates trapping and a double-barrel superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass to treat two fusiform aneurysms in a left dolichoectatic superior MCA trunk. A 46-year-old man with AIDS presented with aphasia and hemiparesis. IRB approval and patient consent were obtained. Both STA branches (frontal and parietal) were harvested. After widely splitting the sylvian fissure from its proximal portion to the angular gyrus, the two fusiform aneurysms on the superior MCA trunk were identified in the insular recess and the circular sulcus. The outflow artery from each aneurysm was identified and prepared for the bypass. The STA was transected, and both limbs were brought down into the fissure. After trapping the distal aneurysm, an end-to-end anastomosis of the parietal STA branch to the M2 MCA was performed. Thereafter, a second bypass was performed in an end-to-side fashion to an M2 branch from the base of the first aneurysm. The second aneurysm was then trapped. Indocyanine green angiography confirmed the patency of both bypasses. Complete aneurysm occlusion and bypass patency were also confirmed with postoperative angiography. The patient recovered from his pre-operative neurological deficits. This case demonstrates the efficacy of double-barrel STA-MCA bypass in combination with aneurysm trapping in a patient with a complex dolichoectatic superior MCA trunk aneurysm. It also highlights the advantage of using end-to-end anastomosis for deep recipients with limited access 3).

A 63-year-old man presented with repeat neurological symptoms such as dizziness, nausea, vomiting, dysarthria, left hemiparesis, and right hemianopsia. Magnetic resonance imaging revealed multiple posterior infarctions. Angiography revealed the VA to be occluded and reconstituted by collateral vessels. Considering the above results, we performed vertebral carotid artery transposition. However, several technical difficulties were encountered due to space limitations in the operative field and the limited length of the vessels to be anastomosed. To overcome such situations, we introduced a modified posterior wall end-to-side anastomosis technique 4).


In this 3-dimensional video, we perform a side-to-side and end-to-side double anastomosis using the parietal-branch of the superficial temporal artery (STA) to provide flow augmentation in a symptomatic 59-yr-old male with bilateral internal carotid artery occlusion at the origin, and left M1 segment occlusion. The patient suffered multiple left hemispheric strokes despite maximal medical therapy and was found to have poor hemodynamic reserve in the left hemisphere during evaluation with regional and global blood oxygenation level-dependent functional magnetic resonance imaging with CO2-challenge as well as quantitative magnetic resonance angiography and noninvasive optimal vessel analysis pre- and post-acetazolamide challenge. Postoperatively, the patient did very well and his hemodynamic studies improved significantly. The importance of this technique relies on the fact that we are using a single donor vessel to perform 2 anastomoses, and carries the following advantages: (1) the frontal STA branch remains intact and therefore can still be used at a later time if further revascularization is needed; (2) wound complications related to devascularizing the scalp from harvesting both STA branches are reduced; (3) 2 vascular territories are augmented (frontal and temporal) while using a single donor; (4) we are maximizing donor potential and optimizing cut flow index (CFI; total bypass flow postanastomosis divided by bypass cut flow) by flow augmenting 2 separate vascular beds therefore increasing demand. To explain that fourth point further: if the STA donor is able to carry a maximum 100 mL/min when cut, and after performing the first anastomosis bypass flow is only 37 mL/min, CFI will be 37/100 = 0.37, reflecting low demand, a poor indicator of graft patency, as previously published.1,2 By adding a second anastomosis which demands an additional 60 mL/min from the same STA donor, CFI (60 + 37)/100 improves to 1. Institutional Review Board approval was obtained for the review of patient chart and video files. Informed consent was obtained directly from the patient via telephone regarding use of media for educational and publication purposes 5).



Yin X, Ye G, Lu J, Wang L, Qi P, Wang H, Wang J, Hu S, Yang X, Chen K, Wang D. A Novel Rat Model for Comprehensive MicrovascularTraining of End-to-EndEnd-to-Side, and Side-to-Side Anastomoses. J Reconstr Microsurg. 2019 Mar 5. doi: 10.1055/s-0039-1679957. [Epub ahead of print] PubMed PMID: 30836413.

Tayebi Meybodi A, Belykh EG, Aklinski J, Kaur P, Preul MC, Lawton MT. The End-to-Side Anastomosis: A Comparative Analysis of Arterial Models in the Rat. World Neurosurg. 2018 Nov;119:e809-e817. doi: 10.1016/j.wneu.2018.07.271. Epub 2018 Aug 8. PubMed PMID: 30096493.

Gandhi S, Rodriguez RL, Tabani H, Burkhardt JK, Benet A, Lawton MT. Double-Barrel Extracranial-Intracranial Bypass and Trapping of Dolichoectatic Middle Cerebral Artery Aneurysms: 3-Dimensional Operative Video. Oper Neurosurg (Hagerstown). 2019 Jan 30. doi: 10.1093/ons/opy311. [Epub ahead of print] PubMed PMID: 30715471.

Seung WB. A Modified Surgical Technique for Transposition of the Vertebral Artery to the Common Carotid Artery. Case Rep Neurol. 2018 Oct 9;10(3):292-296. doi: 10.1159/000493725. eCollection 2018 Sep-Dec. PubMed PMID: 30483104; PubMed Central PMCID: PMC6244107.

Arnone GD, Hage ZA, Charbel FT. Side-to-Side and End-to-Side Double Anastomosis Using the Parietal-Branch of the Superficial Temporal Artery-A Novel Technique for Extracranial to Intracranial Bypass Surgery: 3-Dimensional Operative Video. Oper Neurosurg (Hagerstown). 2019 Jan 1;16(1):112-114. doi: 10.1093/ons/opy091. PubMed PMID: 29660052.

Timed Up and Go test

Timed Up and Go test

Clinical studies on patients with lumbar degenerative diseases increasingly employ objective measures of function, which offer high potential for improving the quality of outcome measurement in patient-care and research.

The Timed Up and Go test (TUG) is a simple test used to assess a person’s mobility and requires both static and dynamic balance.

It has previously been described as a reliable tool to evaluate objective functional impairment in patients with lumbar degenerative disc disease.

It uses the time that a person takes to rise from a chair, walk three metres, turn around, walk back to the chair, and sit down. During the test, the person is expected to wear their regular footwear and use any mobility aids that they would normally require.

The TUG is used frequently in the elderly population, as it is easy to administer and can generally be completed by most older adults.

Of 2389 identified articles, 82 were included in the final analysis. There was a significant increase of 0.12 per year in the number of publications dealing with objective measures of function since 1989 (95% CI 0.08-0.16, p<0.001). Some publications studied multiple diagnoses and objective measures. The US was the leading nation in terms of scientific output for objective outcome measures (n=21; 25.6%), followed by Switzerland (n=17; 20.7%), Canada, Germany and the United Kingdom (each n=6; 7.3%).

The search revealed 21 different types of objective measures, predominantly applied to patients with lumbar spinal stenosis (n=67 publications; 81.7%), chronic/unspecific low back pain (n=28; 34.2%) and lumbar disc herniation (n=22; 26.8%). The Timed-Up-and-Go (TUG) test was the most frequently applied measure (n=26 publications; 31.7%; cumulative number of reported subjects: 5181), followed by the Motorized Treadmill Test (MTT; n=25 publications; 30.5%, 1499 subjects) and with each n=9 publications (11.0%) the Five Times Sit-to-Stand (5R-STS; 955 subjects), as well as accelerometry analyses (336 subjects). The reliability and validity of many of the less-applied objective measures was uncertain. There was profound heterogeneity in their application and interpretation of results. Risk of bias was not assessed. 1).

Nikaido et al. investigated the differences in postural control disability between idiopathic normal pressure hydrocephalus (iNPH) and Parkinson’s disease (PD).

Twenty-seven iNPH patients, 20 PD patients, and 20 healthy controls (HCs) were examined using the Timed Up and Go test (TUG) and a force platform for recording the center of pressure (COP) trajectory during quiescent standing and voluntary multidirectional leaning (forward, backward, right, and left for 10 s each).

In the leaning task, postural control in PD patients was impaired during forward and backward leaning, whereas postural control in iNPH patients was impaired in all directions. In particular, postural control during right and left leaning was significantly worse in iNPH patients than in PD patients. No significant difference was observed between iNPH and PD patients in TUG and postural sway during quiescent standing.

The results showed that the characteristics of impaired voluntary COP control in iNPH and PD patients might reflect pathophysiological differences in postural instability for each disease. In particular, postural instability during right and left leaning in iNPH patients may be responsible for wider steps and a higher risk of falling 2).

One source suggests that scores of ten seconds or less indicate normal mobility, 11 – 20 seconds are within normal limits for frail elderly and disabled patients, and greater than 20 seconds means the person needs assistance outside and indicates further examination and intervention. A score of 30 seconds or more suggests that the person may be prone to falls.

Alternatively, a recommended practical cut-off value for the TUG to indicate normal versus below normal performance is 12 seconds.

A study by Bischoff et al. showed the 10th to 90th percentiles for TUG performance were 6.0 to 11.2 seconds for community-dwelling women between 65 and 85 years of age, and determined that this population should be able to perform the TUG in 12 seconds or less.

TUG performance has been found to decrease significantly with mobility impairments. Residential status and physical mobility status have been determined to be significant predictors of TUG performance.

The TUG was developed from a more comprehensive test, the Get-Up and Go Test.

Research has shown the Timed up and Go test has excellent interrater (intraclass correlation coefficient [ICC] = .99) and intrarater reliability (ICC = .99).[8] The test score also correlates well with gait speed (r = -.55), scores on the Berg Balance Scale (r = -.72), and the Barthel Index (r = -.51).

Many studies have shown good test-restest reliability in specific populations such as community-dwelling older adults and people with Parkinson’s disease.

The TUG Test (measured in seconds) was correlated with validated patient-reported outcome measures (PROs) of pain intensity (Visual Analog Scale for back and leg pain), functional impairment (Oswestry Disability Index, Roland Morris Disability Index), and health-related quality of life measures (Short Form-12 and EuroQol 5D). Three established methods were used to establish anchor-based MCID values using responders of the following PROs (Visual Analog Scale back and leg pain, Oswestry Disability Index, Roland Morris Disability Index, EuroQol 5D index, and Short Form-12 Physical Component Summary) as anchors: (1) average change, (2) minimum detectable change, and (3) change difference approach.

One hundred patients with a mean ± SD age of 56.2 ± 16.1 years, 57 (57%) male, 45 patients undergoing microdiscectomy, 35 undergoing lumbar decompression, and 20 undergoing fusion surgery were studied. The 3 MCID computation methods revealed a range of MCID values according to the PRO used from 0.9 s (Oswestry Disability Index based on the change difference approach) to 6.0 s (EuroQol 5D index based on the minimum detectable change approach), with a mean MCID of 3.4 s for all measured PROs.

The MCID for the TUG Test time is highly variable depending on the computation technique used. The average TUG Test MCID was 3.4 s using all 3 methods and all anchors 3).

The TUG test is preferred over a battery of PROMs by 60-70% of patients with lumbar DDD not only in the preoperative, but also in the postoperative setting. High functional disability does not result in avoidance of the TUG test and repeated assessments lead to higher preference4).



Stienen MN, Ho AL, Staartjes VE, Maldaner N, Veeravagu A, Desai A, Gautschi OP, Bellut D, Regli L, Ratliff JK, Park J. Objective measures of functional impairment for degenerative diseases of the lumbar spine: a systematic review of the literature. Spine J. 2019 Mar 1. pii: S1529-9430(19)30076-2. doi: 10.1016/j.spinee.2019.02.014. [Epub ahead of print] Review. PubMed PMID: 30831316.

Nikaido Y, Akisue T, Kajimoto Y, Tucker A, Kawami Y, Urakami H, Iwai Y, Sato H, Nishiguchi T, Hinoshita T, Kuroda K, Ohno H, Saura R. Postural instability differences between idiopathic normal pressure hydrocephalus and Parkinson’s disease. Clin Neurol Neurosurg. 2018 Jan 10;165:103-107. doi: 10.1016/j.clineuro.2018.01.012. [Epub ahead of print] PubMed PMID: 29331870.

Gautschi OP, Stienen MN, Corniola MV, Joswig H, Schaller K, Hildebrandt G, Smoll NR. Assessment of the Minimum Clinically Important Difference in the Timed Up and Go Test After Surgery for Lumbar Degenerative Disc Disease. Neurosurgery. 2016 Jun 24. [Epub ahead of print] PubMed PMID: 27352275.
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