Study on the clinical application of pulsed DC magnetic technology for tracking of intraoperative head motion during frameless stereotaxy

BACKGROUND: Tracking of post-registration head motion is one of the major problems in frameless stereotaxy. Various attempts in detecting and compensating for this phenomenon rely on a fixed reference device rigidly attached to the patient's head. However, most of such reference tools are either based on an invasive fixation technique or have physical limitations which allow mobility of the head only in a restricted range of motion after completion of the registration procedure. METHODS: A new sensor-based reference tool, the so-called Dynamic Reference Frame (DRF) which is designed to allow an unrestricted, 360° range of motion for the intraoperative use in pulsed DC magnetic navigation was tested in 40 patients. Different methods of non-invasive attachment dependent on the clinical need and type of procedure, as well as the resulting accuracies in the clinical application have been analyzed. RESULTS: Apart from conventional, completely rigid immobilization of the head (type A), four additional modes of head fixation and attachment of the DRF were distinguished on clinical grounds: type B1 = pin fixation plus oral DRF attachment; type B2 = pin fixation plus retroauricular DRF attachment; type C1 = free head positioning with oral DRF; and type C2 = free head positioning with retroauricular DRF. Mean fiducial registration errors (FRE) were as follows: type A interventions = 1.51 mm, B1 = 1.56 mm, B2 = 1.54 mm, C1 = 1.73 mm, and C2 = 1.75 mm. The mean position errors determined at the end of the intervention as a measure of application accuracy were: 1.45 mm in type A interventions, 1.26 mm in type B1, 1.44 mm in type B2, 1.86 mm in type C1, and 1.68 mm in type C2. CONCLUSION: Rigid head immobilization guarantees most reliable accuracy in various types of frameless stereotaxy. The use of an additional DRF, however, increases the application scope of frameless stereotaxy to include e.g. procedures in which rigid pin fixation of the cranium is not required or desired. Thus, continuous tracking of head motion allows highly flexible variation of the surgical strategy including intraoperative repositioning of the patient without impairment of navigational accuracy as it ensures automatic correction of spatial distortion. With a dental cast for oral attachment and the alternative option of non-invasive retroauricular attachment, flexibility in the clinical use of the DRF is ensured

The endoscopic treatment of fourth ventricle outlet obstruction: Report of two children and systematic review

Key Clinical Message Fourth ventricle outlet obstruction (FVOO) is a rare cause of hydrocephalus. In the last century, the standard treatment was the suboccipital craniotomy with magendieplasty or ventriculoperitoneal shunt (VP shunt). Since the beginning of the 21st century, the endoscopic third ventriculostomy (ETV) has been considered a less invasive alternative. The medical literature lacks sufficient reports of FVOO cases and strong evidence about ETV's efficacy in treating this condition. We report two cases of FVOO treated with ETV and review published similar cases. Clinical and radiological findings of two FVOO cases with outcomes after ETV were presented. Moreover, we conducted a systematic review after protocol registration in PROSPERO (CRD42021281474). MEDLINE, Embase, Scopus, and Web of Science were searched from inception till December 31, 2022. Studies were included if they reported cases of FVOO treated initially with ETV. Cases with Chiari malformation, Dandy‐Walker malformation, tuberous sclerosis, trapped fourth ventricle, or space‐occupying lesions were excluded. Two reviewers independently examined title/abstract records in the first stage and full‐text publications in the second for eligibility. The primary outcome was the recurrence rate, defined by the need for re‐ETV or other invasive treatments (e.g., VP shunt or magendieplasty). Other outcomes included clinical state at follow‐up and mortality. Two cases, a 3‐year‐old male and 3.5‐year‐old female, with FVOO, were treated with ETV in our department by the same neurosurgeon (SH) in 2013 and 2021. Both cases improved significantly after ETV, and there was no recurrence through the follow‐up. Besides the present cases, we found 57 other cases of FVOO treated with ETV reported in 17 studies between 2001 and 2021. The median age was 26 years, with an IQR from 2.4 to 59 years, and 56% of cases were females. The recurrence rate was 32% in the sample (19 out of 59), with a 95% CI from 21% to 46%. The median time to recure was 2 months with IQR from 1.25 to 26. A VP shunt was the treatment for recurrence in 68% and a re‐ETV in 32%. At the follow‐up (41 ± 29 months), only one case died, and one deteriorated clinically. FVOO is a rare cause of hydrocephalus encountered mainly in the first or sixth decades of life. ETV provides the first reasonable treatment. Despite the moderate recurrence rate, the outcomes are favorable

The role of neuromuscular ultrasound in diagnostics of peripheral neuropathies induced by cytostatic agents or immunotherapies

Abstract A relevant number of cancer patients who receive potentially neurotoxic cytostatic agents develop a chemotherapy-induced peripheral neuropathy over time. Moreover, the increasing use of immunotherapies and targeted agents leads to a raising awareness of treatment-associated peripheral neurotoxicity, e.g., axonal and demyelinating neuropathies such as Guillain–Barré-like syndromes. To date, the differentiation of these phenomena from concurrent neurological co-morbidities or (para-)neoplastic nerve affection as well as their longitudinal monitoring remain challenging. Neuromuscular ultrasound (NMUS) is an established diagnostic tool for peripheral neuropathies. Performed by specialized neurologists, it completes clinical and neurophysiological diagnostics especially in differentiation of axonal and demyelinating neuropathies. No generally approved biomarkers of treatment-induced peripheral neurotoxicity have been established so far. NMUS might significantly extend the repertoire of diagnostic and neuromonitoring methods in this growing patient group in short term. In this article, we present enlargements of the dorsal roots both in cytostatic and in immunotherapy-induced neurotoxicity for the first time. We discuss related literature regarding new integrative applications of NMUS for cancer patients by reference to two representative case studies. Moreover, we demonstrate the integration of NMUS in a diagnostic algorithm for suspected peripheral neurotoxicity independently of a certain cancer treatment regimen emphasizing the emerging potential of NMUS for clinical routine in this interdisciplinary field and prospective clinical trials

Additional file 1 of The role of neuromuscular ultrasound in diagnostics of peripheral neuropathies induced by cytostatic agents or immunotherapies

Additional file 1. Table S1: Detailed NMUS measurements of the presented patients