Awake craniotomies

Imagine lying awake on the operating table during a procedure. Seems wrong, yes? Now picture having surgery on your brain at the same time.

That’s an ‘awake craniotomy’. Unless you’ve known someone with a brain tumour, or someone that worked in a neuro-oncology service, you may not have known they existed. On the surface, the concept feels shocking and daunting, but when you start to consider the better outcomes, preparation and support that awake surgery promotes, the idea becomes much more acceptable.

Awake craniotomies are offered primarily to those with brain tumours. Research has shown that awake craniotomies are most common in people with Low Grade Gliomas, for a number of reasons, including surgical potential. Despite this, there is growing evidence of awake surgery with High Grade Gliomas, Metastases, Cavernomas and Epilepsy. If neurosurgeons feel that the tumour location is in or close to so-called 'eloquent' brain areas – usually areas linked to language and motor skills – they may offer awake surgery.

Here, I consider the important – and changing – role that neuropsychologists and assistant psychologists play in the procedure.

Pre-assessment

Most awake craniotomies involve monitoring language during the procedure. Currently, many centres across the UK are exploring the use of paradigms which monitor frontal functions including planning, problem solving and attention.

Prior to the surgery, patients will undergo pre-operative assessments. These include regular CTs and MRIs at the request of the neurosurgeon, but also include a battery of cognitive assessments to determine the person’s performance prior to surgery. Using this information, an individualistic intraoperative plan is created to include paradigms specific to brains areas and function, and these are ‘practiced’ to collate a ‘baseline’. This ensures patients are able to sufficiently complete assessments prior to the surgery; subtests that cannot be completed are simply removed from the intraoperative agenda to ensure optimum performance throughout.

The cognitive assessment battery will give a clear image of how the lesion may or may not have already impacted cognitive function, and provide a pre-treatment baseline to monitor going forward. These assessments also help highlight the patient’s strengths and weaknesses in terms of their cognition, and help inform care plans and treatments.

Preoperative preparation

Once pre-treatment baselines have been collated and a surgery plan has been devised and agreed, the surgery goes ahead. There are various approaches to awake craniotomies; Asleep Awake Asleep (SAS), Awake Awake Awake (AAA) or Monitored Anaesthesia Care (MAC). Essentially, all three of these approaches have one thing in common; patients are awake for the stimulation and resection phases of the surgery.

Monitored Anaesthesia Care (MAC) empowers the patient in autonomous and person-centred care, whilst considering opinions of multi-disciplinary team members, including neurosurgeons, anaesthetists, neuropsychologists, physiotherapists, nurses and others. Typically, local anaesthesia is applied under the scalp and a clamp is used to ensure the head remains in a fixed position. In the operating theatre, there is a computer screen with a digital composition of the patients head and brain (created using pre-operative MRI imaging). The digital image is calibrated with the electronic stimulator (probe) to ensure accurate representation and cortical mapping of the patient’s anatomy.

Phase 1: Stimulation/Brain Mapping

Once a patient’s anatomy is calibrated with the cortical mapping equipment, the neurosurgeon injects more local anaesthetic under the scalp and makes an incision around the surgical site. The scalp is then clipped back to expose the skull. A drill is then used to cut out a piece of the skull and expose the brain.

During the stimulation phase of the surgery, the neurosurgeon places a probe around the margins of the suspected lesion and stimulates an electrical pulse which ‘switches off’ that area of the brain for around four seconds. Within these four seconds, patients are asked by either the neuropsychologist or physiotherapist to complete a task, dependent on the location of the tumour. The idea is that if the probe is touching unhealthy brain tissue (tumour/lesion), patients will be able to complete the task as normal. However, if the neurosurgeon is stimulating healthy brain tissue, the patient will encounter problems and won’t be able to do it. If this is the case, they might make an error, hesitate, or struggle to speak entirely. 

Once the task is completed, and the area is identified as either healthy or unhealthy brain tissue, an electronic marker is placed to ensure the surgeon is aware of areas they should/should not resect. This phase is thorough and often repetitive, but essential in further informing the surgical plan.

Phase 2: Tumour Resection

The next phase of the surgery is the resection phase, whereby the neurosurgeon begins to resect the lesion. This phase makes up the majority of the surgery, and can often be the phase which comes with challenges and obstacles. Due to the brain having no pain receptors, patients do not experience any pain. Despite this, similar to dentist procedures, patients often report discomfort due to positioning and ‘pushing and pulling’ sensations. Patients may also experience pain in the dura and scalp which can be managed intraoperatively. The intraoperative paradigms are constantly repeated throughout the resection phase of the surgery, dependent on the area of the lesion that the neurosurgeon is resecting.

The surgical team constantly monitor the patient and communicate between themselves to ensure nuances changes in performance and presentation are acknowledged and the surgical plan adjusted if and where necessary. The nature of awake craniotomies means that patients may also present with seizure activity throughout; if so, ice water is poured directly onto the brain, until it passes. This section can be laborious for patients due to its repetitiveness and lengthy duration. It’s likely that due to anxiety and other factors, patients may have had poor sleep leading up to the surgery. Due to the demands on the patient preoperatively and intraoperatively it is not unusual for them to experience fatigue and anxiety; these issues need to be closely monitored and supported by the neuropsychologist and surgical team to consider how and when these are contributing to intraoperative performance.

Phase 3: Closure

The final phase of an awake craniotomy is the closure phase. Once the lesion has been resected as much as possible, the bone flap is reattached with screws, and the scalp is stitched. During this phase, the patient tends to be less active, as there is less cognitive demand. The team ensure the patient is comfortable and may engage in general conversation or provide emotional support. Patients tend to use this phase to rest and relax, and may be sedated so sleep through this. Patients are usually taken to an observation area whereby they are monitored closely by staff for a few hours.

Inpatient admissions following awake craniotomies tend to typically last approximately 2 -7 days dependent on any post-operative issues. Due to swelling and other expected post-surgical effects, patients may present with cognitive impairment immediately following surgery; however, this tends to resolve with time and anti-inflammatory medication such as steroids.

The role of the Assistant Psychologist

The role of an Assistant Psychologist in Awake Craniotomies is exactly that; to assist the Neuropsychologist. Assistant Psychologists within areas of Neuropsychology tend to be trained on administering and scoring cognitive assessments, which means that they are usually responsible for collating pre-treatment baselines and cross-referencing and collecting relevant history and evidence. This provides an outline of potential symptoms and challenges that may further inform the treatment plan.

Due to the standardised yet individualistic approach we take for Awake Craniotomies, Assistant Psychologists support in creating person-centred intraoperative paradigms for the patient, under the supervision of a neuropsychologist. This surrounds collecting all paradigms which efficaciously monitor the tumour location in question, alongside removing any tasks or subtests the patient could not complete sufficiently during the pre-treatment baselines. This allows for smoother transitions between paradigms intraoperatively, whilst ensuring evidence-based tasks are administered to provide best treatment outcomes.

During surgery, the Assistant Psychologist’s role mostly surrounds supporting the Neuropsychologist with tasks such as setting up paradigm equipment, recording responses, recording response timings and recording phase commencement and/or duration. Occasionally, the Assistant Psychologist may also provide emotional support, implementation of developed emotional regulation strategies or engaging the patient in general conversation. Throughout the surgery, both the Neuropsychologist and Assistant Psychologist can provide reassurance and emotional support if and where necessary.

Following recovery from surgery, whether further treatment is recommended or not, neuro-oncology patients are given the opportunity to partake Neuropsychological Monitoring. This includes annual mood and cognition reviews, alongside repeating the cognitive assessment battery the patient initially completed prior to surgery. This allows the MDT to closely monitor changes in cognitive function, which could further identify potential tumour regrowth or disease progression. The Assistant Psychologist is responsible for completing the reviews, administering and scoring the cognitive assessments.

A new direction

More recently, research and advances in treatments have explored developing intraoperative paradigms to explore a wider array of cognitive functions, including social cognition and executive function. Teams and centres have also experimented with innovative ways to administer paradigms intraoperatively, including the use of technology such as iPads and software such as Microsoft Powerpoint. Most recently, the new release of the Neuromapper iOS App has seen an increasing number of centres explore the administration of comprehensive, conceptually informed intraoperative tasks.

There are certainly benefits to using advanced technology within Awake Craniotomies; increased validity in measuring reaction times, more extensive testing in a shorter time, and ease of administration for the Neuropsychologist. Despite this, adapting an already fine-tuned procedure can seem effortful and daunting. Acclimatising to new procedures, engaging in further training, and perfecting these skills intraoperatively comes with challenges and obstacles; but these adaptations are necessary in ensuring the patient receives the highest level of care.

How might the role of Assistant Psychologists support this transition? Assistant Psychologists could support Neuropsychologists intraoperatively with equipment and software setup, administration of paradigms and transitions between tasks. Alongside this, they could act as a ‘back up’ in case of technological issues, providing alternative paradigm sources and recording equipment. Whilst the role of the Assistant Psychologist could be interpreted as an ‘accessory’ to Awake Craniotomies, their presence and support throughout surgeries could potentially smooth an otherwise daunting transition to a more technologically advanced approach to intraoperative assessments.

• Georgia Wilson is an Assistant Psychologist with Humber Teaching NHS Foundation Trust