A risk assessment strategy to re-introduce elective neurosurgery patients during COVID-19

OBJECTIVES

To demonstrate the utilisation of a risk assessment protocol designed to prioritise elective neurosurgical patients against the risks of COVID-19. This tool can be applied to all other surgical specialties.

DESIGN

Prospective case series of 166 patients.

SETTING

Single-centre tertiary neurosurgical department.

PARTICIPANTS

All patients awaiting an elective neurosurgical procedure were included in this study. All emergency or life-threatening neurosurgical pathologies affecting patients were excluded.

MAIN OUTCOME MEASURES

The risk assessment tool identified patients with progressive neurology and stratified need for surgery against risk of harm during the COVID-19 pandemic.

RESULTS

Using our risk stratification tool, 6.6% patients required expedited surgery and a further 11.4% patients were removed completely from the waiting list. The majority of patients 47%, required surgery within 3 months.

CONCLUSIONS

This simple tool encourages surgical departments to establish contact with patients during COVID-19. The clinician acquires up-to-date information regarding patient symptomatology and subsequently determines surgical priority, a timescale required for surgery and overall uses of NHS resources efficiently. We recommend the use of this tool for all neurosurgical departments, with a wider application to other surgical specialties during the ongoing pressures of elective backlogs secondary to the persistent COVID-19 pandemic.

Intraparenchymal convection enhanced delivery of AAV in sheep to treat Mucopolysaccharidosis IIIC

BACKGROUND

Mucopolysaccharidosis IIIC (MPSIIIC) is one of four Sanfilippo diseases sharing clinical symptoms of severe cognitive decline and shortened lifespan. The missing enzyme, heparan sulfate acetyl-CoA: α-glucosaminide-N-acetyltransferase (HGSNAT), is bound to the lysosomal membrane, therefore cannot cross the blood-brain barrier or diffuse between cells. We previously demonstrated disease correction in MPSIIIC mice using an Adeno-Associated Vector (AAV) delivering HGSNAT via intraparenchymal brain injections using an AAV2 derived AAV-truetype (AAV-TT) serotype with improved distribution over AAV9.

METHODS

Here, intraparenchymal AAV was delivered in sheep using catheters or Hamilton syringes, placed using Brainlab cranial navigation for convection enhanced delivery, to reduce proximal vector expression and improve spread.

RESULTS

Hamilton syringes gave improved AAV-GFP distribution, despite lower vector doses and titres. AAV-TT-GFP displayed moderately better transduction compared to AAV9-GFP but both serotypes almost exclusively transduced neurons. Functional HGSNAT enzyme was detected in 24-37% of a 140g gyrencephalic sheep brain using AAV9-HGSNAT with three injections in one hemisphere.

CONCLUSIONS

Despite variabilities in volume and titre, catheter design may be critical for efficient brain delivery. These data help inform a clinical trial for MPSIIIC.

Awake brain surgery for autistic patients: Is it possible?

Background:

Awake neurosurgery is currently the mainstay for eloquent brain lesions. Opting for an awake operation is affected by a number of patient-related factors. We present a case of a patient with autistic spectrum disorder (ASD) that was successfully operated for a brain tumor through awake craniotomy. To the best of our knowledge, this is the first reported case in the literature.

Case Description:

A 42-year-old patient, with known ASD since his childhood, underwent awake craniotomy for a left supplementary motor area tumor. Detailed preoperative preparation of the patient was done to identify special requirements and establish a good patient-team relationship. Intraoperatively, continuous language and motor testing were performed. Conversation and music were the main distractors used. Throughout the operation, the patient remained calm and cooperative, even during a focal seizure. Mapping allowed for >80% resection of the tumor. Postoperatively, the patient recovered without any deficits.

Conclusion:

This case shows that with growing experience and meticulous preparation, the limits of awake craniotomy can be expanded to include more patients that were previously considered unfit.

A novel adeno-associated virus capsid with enhanced neurotropism corrects a lysosomal transmembrane enzyme deficiency

Recombinant adeno-associated viruses (AAVs) are popular in vivo gene transfer vehicles. However, vector doses needed to achieve therapeutic effect are high and some target tissues in the central nervous system remain difficult to transduce. Gene therapy trials using AAV for the treatment of neurological disorders have seldom led to demonstrated clinical efficacy. Important contributing factors are low transduction rates and inefficient distribution of the vector. To overcome these hurdles, a variety of capsid engineering methods have been utilized to generate capsids with improved transduction properties. Here we describe an alternative approach to capsid engineering, which draws on the natural evolution of the virus and aims to yield capsids that are better suited to infect human tissues. We generated an AAV capsid to include amino acids that are conserved among natural AAV2 isolates and tested its biodistribution properties in mice and rats. Intriguingly, this novel variant, AAV-TT, demonstrates strong neurotropism in rodents and displays significantly improved distribution throughout the central nervous system as compared to AAV2. Additionally, sub-retinal injections in mice revealed markedly enhanced transduction of photoreceptor cells when compared to AAV2. Importantly, AAV-TT exceeds the distribution abilities of benchmark neurotropic serotypes AAV9 and AAVrh10 in the central nervous system of mice, and is the only virus, when administered at low dose, that is able to correct the neurological phenotype in a mouse model of mucopolysaccharidosis IIIC, a transmembrane enzyme lysosomal storage disease, which requires delivery to every cell for biochemical correction. These data represent unprecedented correction of a lysosomal transmembrane enzyme deficiency in mice and suggest that AAV-TT-based gene therapies may be suitable for treatment of human neurological diseases such as mucopolysaccharidosis IIIC, which is characterized by global neuropathology.

A nonmyeloablative chimeric mouse model accurately defines microglia and macrophage contribution in glioma

Aims

Resident and peripherally derived glioma associated microglia/macrophages (GAMM) play a key role in driving tumour progression, angiogenesis, invasion and attenuating host immune responses. Differentiating these cells’ origins is challenging and current preclinical models such as irradiation‐based adoptive transfer, parabiosis and transgenic mice have limitations. We aimed to develop a novel nonmyeloablative transplantation (NMT) mouse model that permits high levels of peripheral chimerism without blood‐brain barrier (BBB) damage or brain infiltration prior to tumour implantation.

Methods

NMT dosing was determined in C57BL/6J or Pep3/CD45.1 mice conditioned with concentrations of busulfan ranging from 25 mg/kg to 125 mg/kg. Donor haematopoietic cells labelled with eGFP or CD45.2 were injected via tail vein. Donor chimerism was measured in peripheral blood, bone marrow and spleen using flow cytometry. BBB integrity was assessed with anti‐IgG and anti‐fibrinogen antibodies. Immunocompetent chimerised animals were orthotopically implanted with murine glioma GL‐261 cells. Central and peripheral cell contributions were assessed using immunohistochemistry and flow cytometry. GAMM subpopulation analysis of peripheral cells was performed using Ly6C/MHCII/MerTK/CD64.

Results

NMT achieves >80% haematopoietic chimerism by 12 weeks without BBB damage and normal life span. Bone marrow derived cells (BMDC) and peripheral macrophages accounted for approximately 45% of the GAMM population in GL‐261 implanted tumours. Existing markers such as CD45 high/low proved inaccurate to determine central and peripheral populations while Ly6C/MHCII/MerTK/CD64 reliably differentiated GAMM subpopulations in chimerised and unchimerised mice.

Conclusion

NMT is a powerful method for dissecting tumour microglia and macrophage subpopulations and can guide further investigation of BMDC subsets in glioma and neuro‐inflammatory diseases.

High content screening of patient-derived cell lines highlights the potential of non-standard chemotherapeutic agents for the treatment of glioblastoma

BACKGROUND

Glioblastoma (GBM) is the most common primary brain malignancy in adults, yet survival outcomes remain poor. First line treatment is well established, however disease invariably recurs and improving prognosis is challenging. With the aim of personalizing therapy at recurrence, we have established a high content screening (HCS) platform to analyze the sensitivity profile of seven patient-derived cancer stem cell lines to 83 FDA-approved chemotherapy drugs, with and without irradiation.

METHODS

Seven cancer stem cell lines were derived from patients with GBM and, along with the established cell line U87-MG, each patient-derived line was cultured in tandem in serum-free conditions as adherent monolayers and three-dimensional neurospheres. Chemotherapeutics were screened at multiple concentrations and cells double-stained to observe their effect on both cell death and proliferation. Sensitivity was classified using high-throughput algorithmic image analysis.

RESULTS

Cell line specific drug responses were observed across the seven patient-derived cell lines. Few agents were seen to have radio-sensitizing effects, yet some drug classes showed a marked difference in efficacy between monolayers and neurospheres. In vivo validation of six drugs suggested that cell death readout in a three-dimensional culture scenario is a more physiologically relevant screening model and could be used effectively to assess the chemosensitivity of patient-derived GBM lines.

CONCLUSION

The study puts forward a number of non-standard chemotherapeutics that could be useful in the treatment of recurrent GBM, namely mitoxantrone, bortezomib and actinomycin D, whilst demonstrating the potential of HCS to be used for personalized treatment based on the chemosensitivity profile of patient tumor cells.

Escherichia coli positive infratentorial subdural empyema secondary to mastoiditis and underlying cholesteatoma

Infratentorial subdural empyema is a neurosurgical emergency that is associated with an alarmingly high morbidity and mortality if appropriate management is delayed. It is an important differential to consider when confronted with a patient with a reduced Glasgow Coma Scale, focal neurology and symptoms of raised intracranial pressure in the presence of a head and neck infection. It is also important that the primary team managing these patients is aware of the many pathogens that may be involved, including Escherichia coli. Early recognition, prompt diagnosis, timely involvement of the appropriate multidisciplinary teams, including neurosurgery, otorhinolaryngology, radiology and microbiology should be sought, and urgent intervention are imperative in avoiding a fatal outcome. This article presents a case of E coli-positive infratentorial subdural empyema secondary to mastoiditis due to underlying cholesteatoma, and a review of the pertinent literature.

Management of Bell's palsy in children: an audit of current practice, review of the literature and a proposed management algorithm

OBJECTIVE

We carried out a complete audit cycle, reviewing our management of paediatric patients with Bell's palsy within 72 h of symptom onset. Our protocol was published after the initial audit in 2009, and a re-audit was carried out in 2011. We aimed to improve our current practice in accordance with up-to-date evidence-based research on the use of steroids and antivirals.

PATIENTS AND METHODS

A total of 17 patients were included in the first cycle, but only eight patients met our inclusion and exclusion criteria for the re-audit. We assessed documentation of House-Brackmann (HB) grade on presentation, initial treatment, follow-up and recovery.

RESULTS

The first cycle revealed inconsistent management with steroids (41%), antivirals (6%), steroids and antivirals (6%) or nothing at all (47%). In addition, only 65% of patients were followed-up in the ear, nose and throat (ENT) clinic. Our management protocol was published in 2010, and a re-audit was completed. Our results showed 100% compliance with steroid treatment and 100% follow-up with the ENT team. A thorough literature review revealed some additional benefit from the use of antivirals.

CONCLUSIONS

At present there is insufficient evidence to discount the use of steroids and antivirals. Therefore, with our new management protocol, we recommend the use of steroids in patients presenting within 72 h of symptom onset, and antivirals for patients with a HB grade of IV or higher.

Day case tonsillectomy for the treatment of obstructive sleep apnoea syndrome in children: Alder Hey experience

BACKGROUND

The aim of this study was to assess the safety of paediatric adeno-tonsillectomy for obstructive sleep apnoea syndrome (OSAS) performed as a day case procedure.

METHODOLOGY

Postoperative airway related complications were prospectively evaluated in children undergoing adeno-tonsillectomy for OSAS over a 12-month period in a tertiary care centre. All data was analysed and descriptive statistics performed.

RESULTS

The overall incidence of postoperative airway related complications were 21 (10.4%) in 202 consecutively operated children. Eleven were in children with other medical co-morbidities (n=37) of which 8 occurred after 6h. Amongst those without any medical illnesses (n=165), two (1.2%) developed OSAS related complication after 6h of surgery only one of which needed medical/nursing intervention. The incidence of postoperative desaturations after 6h was 21.6% in those with co-morbidities.

CONCLUSION

It is safe to perform day case adeno-tonsillectomy for OSAS in children without any medical co-morbidities while those with other medical illnesses should be planned as in-patient procedures.