Neuroanaesthetic challenges in a pregnant patient with a huge cerebellopontine angle meningioma

Abstract

Intracranial malignancy among pregnant women is extremely rare. Neuroanaesthesia for such high-risk patients demands extreme precautions. Our patient presented with a huge right cerebellopontine angle meningioma during the first trimester of her pregnancy. We share our valuable perianaesthetic challenges in managing her tumour-debulking surgery and a brief review of intracranial neoplasm during pregnancy.

Background

The incidences of brain tumour in pregnant women are estimated at 2–3.2 per 100 000 women.¹ Mesenchymal non-meningothelial tumours and meningiomas are the most common histological findings. We describe an interesting case of a pregnant woman at her first trimester who present with a huge cerebellopontine angle (CPA) meningioma, which required a life-saving emergency craniotomy. We describe our neuroanaesthetic challenges during her tumour-debulking surgery in the Park-bench position and review on intracranial neoplasms in pregnant women.

Case presentation

A patient in her late adolescence, with no underlying comorbidities, reported having intermittent headache at her right frontotemporal region for 1 year. She described the headache as throbbing in nature, which radiated to the entire head. The pain worsened when she was doing house chores and relieved by oral analgesics. However, the headache had worsened, and became unbearable for the past 2 weeks prior to presentation to our institution. In addition, she claimed to have persistent spinning sensation of the head and unsteady gait for 1 week prior to admission. She also had reduced hearing over the right ear and tinnitus for 1 week with occasional imbalances during standing. Otherwise, she denied blurring vision, projectile vomiting, history of head trauma, neurological deficits and constitutional symptoms of malignancy. There was no significant family history of malignancies too. She is married and blessed with four healthy children.

On clinical examination, she was alert and conscious. Her blood pressure (BP), pulse rate, respiratory rate and oxygen saturation were 112/78 mm Hg, 72 beats/min, 20 breaths/min and 100% under room air, respectively. Her pupils’ sizes were 3 mm bilaterally and reactive to light with no papilloedema. There were no significant neurological deficits except for a positive Romberg’s sign. There was a mild to moderate mixed sensory neural hearing loss over the right ear, while the left side was normal. There were no tympanic membrane perforations on otoscopic examination. Her abdomen was scaphoid in shape with no palpable masses. Her airway assessment revealed Mallampati 1 with good mouth opening and neck extension.

Investigations

• Her full blood count showed haemoglobin of 112 g/L (normal values: 110–130 g/L), total white cell count of 7.2×10⁹/L (normal values: 5–12×10⁹/L) and platelet of 372×10⁹/L (normal values: 150–450×10⁹/L).

• The biochemical investigations, including liver function tests, were within normal values.

• Her initial CT of the brain showed an extra-axial lesion measuring 3.5×4.7 cm and hyperostosis of the right petrous bone with no widening of the internal auditory meatus.

• Her cerebral MRI showed a well-defined extra-axial lesion at the right CPA measuring 3.7×4.9×2.1 cm (figures 1 and 2). It was isointense at T1-weighted and hyperintense on T2-weighted scans, respectively. The lesion has mass effect to the right internal auditory canal, cerebellum, pons and medulla with the presence of perilesional oedema. It also compressed on the third, fourth and both lateral ventricles to cause mild hydrocephalus. There was no transtentorial or tonsillar herniation.

Figure 1.

Preoperative CT of the brain bone window showing hyperostosis of the right petrous bone and no widening of the internal auditory meatus.

Figure 2.

Preoperative T2-weighted sequence MRI of the brain of our patient, which showed wide base lesion with significant perilesional oedema and mass effect on the right brainstem.

Differential diagnosis

Our provisional diagnosis was a huge right CPA tumour, possibly a meningioma, based on her clinical presentation and MRI findings. Other differential diagnoses are vestibular schwannoma and cerebral abscess. However, the latter is unlikely due to absence of clinical features of sepsis.

Treatment

She was planned for an elective right rectosigmoid and suboccipital craniotomy and tumour debulking. However, 2 weeks prior to her elective admission, she presented with worsening headache, projectile vomiting, vertigo and unsteadiness. Her condition was severe as she needed a walking aid to ambulate. In addition, she admitted to us that she did not have menses for the past 5 weeks. On examination, her Glasgow Coma Scale (GCS) was full and pupils were equal. Her motor and sensory neurological examinations were intact. There were presence of significant right-sided cerebellar signs such as dysdiadochokinesia and nystagmus. Her haemodynamics were stable and a bedside urine pregnancy test was positive. An ultrasonography of the abdomen and pelvis confirmed a viable intrauterine fetus. A repeated cerebral MRI showed an enlarged right CPA tumour measuring 3.8×4.9×2.3 cm compressing onto the right pons, medulla and cerebellum with significant perilesional oedema. There was presence of mild to moderate hydrocephalus.

In view of the severity of her condition, a multidisciplinary team, which comprised of neurosurgeons, neuroanaesthesiologists, neurointensivists, obstetrician, radiologists and oncologists, agreed for an emergency right craniotomy and tumour debulking for our patient. Initially, the neurosurgical team was in great dilemma whether to proceed with only cerebrospinal fluid (CSF) diversion or tumour-debulking surgery. There was no evidence of significant hydrocephalus but there was mass effect onto the right pons, medulla and cerebellum. Our patient was counselled regarding the risk of losing this fetus should we continue with tumour-debulking surgery during the first trimester of her pregnancy. However, if this surgery was delayed, she might deteriorate due to compressive effect onto the brainstem, causing cardiorespiratory compromise. After a detailed discussion, our patient decided for tumour-debulking surgery. Very high-risk consent was obtained, including for this publication, for the surgery. On the eve of the surgery, she was fasted for 8 hours with an intravenous drip. An obstetrician examined and scanned her abdomen, confirming the presence of fetal heartbeat (FHB).

On the day of surgery, she was gently positioned on the operating table. Standard American Society of Anesthesiologists monitors such as non-invasive BP, ECG, pulse oximetry, capnography and temperature probe were placed. After 5 min pre-oxygenation, she was induced with intravenous fentanyl 2 µg/kg, intravenous propofol 2 mg/kg and intravenous rocuronium 1 mg/kg. Rapid sequence intubation was performed, and her trachea was intubated with a flexometallic size 7.0 mm endotracheal tube. Central venous and arterial catheters were inserted onto her right subclavian vein and radial artery, respectively, for resuscitation and monitoring. After that, intravenous tranexamic acid, levetiracetam, mannitol 20% 0.25 g/kg and cefuroxime were administered.

An external ventricular drain (EVD) was inserted with our patient in the supine position and connected to an intracranial pressure (ICP) transducer. This was planned in view of our patient to potentially develop hydrocephalus caused by postoperative cerebral oedema, tumour residual and traction injury to the brainstem and cerebellum. The CSF was colourless with an ICP of less than 10 mm Hg. After that, she was turned into right Park-bench position to facilitate surgical tumour debulking via the suboccipital incision (figure 3). Intraoperative neurophysiological monitoring (IONM) by way of brainstem auditory evoked potential (BAEP), electromyography and motor evoked potential (MEP) was used to guide the neurosurgeons throughout the surgery.

Figure 3.

Our patient in right Park-bench position during surgery.

Anaesthesia was maintained with targeted controlled infusion (TCI) of propofol and remifentanil. They were kept in the range of 3.2–5.8 µg/mL and 2.3–5.0 ng/mL, respectively. Depth of anaesthesia was monitored using a bispectral index (BIS), which was placed on her left forehead. We maintained her cerebral perfusion pressure (CPP) at a range of 60–70 mm Hg as guided by the ICP. The tumour was completely debulked and blood loss was estimated at 800 mL. Her haemoglobin level was 98 g/L and our patient was transfused with two units of packed cells. Our neurosurgeons were extremely gentle and meticulous during resection of the tumour. The feeder vessels to the tumour, which arose from the petrous bone, were devascularised to reduce the risks of bleeding. The brain was not oedematous and there were no significant intraoperative surgical events. The total duration of the surgery was 8 hours and her entire intraoperative haemodynamics were stable.

Outcome and follow-up

Our patient was transferred to the neurocritical care unit (NCU) for weaning and was safely extubated 6 hours later. She did not develop any neurological deficits nor defects to the cranial nerves function with a slightly improved hearing over the right ear. The obstetrician performed an ultrasonography of the abdomen, confirming the presence of FHB. A cerebral MRI done on the second postoperative day showed complete debulking of the tumour and absence of any significant bleeding, infarction or hydrocephalus (figure 4). The EVD was challenged by increasing the height of the chamber by 5 cm daily until it reached 20 cm. It was then clamped for 24 hours to monitor for the presence of signs and symptoms of raised ICP. Our patient developed headache and vomiting at this juncture and an urgent MRI of the brain showed presence of hydrocephalus with minimal perilesional oedema. She was posted for an emergency left ventriculoperitoneal shunt (VPS) insertion in view of failed EVD challenge.

Figure 4.

Postoperative MRI of the brain of our patient showing complete debulking of the right cerebellopontine angle tumour.

She was discharged from the ward at the 12th postoperative day. Upon review in the neurosurgical clinic 2 weeks later, she was alert and conscious. She was able to ambulate well without support, which was equivalent to modified Rankin scale of 2. She still had slight disability, unable to carry out previous activities but able to look after her own affairs without assistance. Her hearing had improved and did not develop body imbalances. Obstetric abdominal scanning showed a thriving fetus.

Her histopathological examination (HPE) of the tumour showed a type I meningioma, which do not require any further chemoradiotherapy. She was followed up every month until her delivery date. She was well throughout and did not develop any symptoms of raised ICP nor worsening neurological deficits.

She safely delivered a healthy baby girl at her 38th week of pregnancy, weighing 3.2 kg, via an elective caesarean section. There were no complications perinatally. The timeline of events of our patient is summarised in figure 5.

Figure 5.

Timeline of events of our patient (drawn by Dr Tat Boon Yeap). VP, ventriculoperitoneal.

Discussion

The incidence of brain tumour among pregnant women is about 2–3.2 per 100 000. The average age of occurrence is about 30–35 years old. The most common histological types are mesenchymal non-meningothelial tumour (24%), diffuse astrocytic oligodendroglial tumour (21%) and meningioma (20%).¹ These tumours are usually detected in the second and third trimesters, possibly due to the maximal influence of oestrogen and progesterone onto the tumour cells.^{1 2} The increased blood volume during pregnancy leads to the engorgement of the peritumoral vascular bed and increases tumour size.

The most common sites of tumour occurrences during pregnancy are at the frontal lobe and cerebellum, while it is extremely rare at the CPA.³ The latter usually abuts from the brainstem and affects the cranial nerves V (trigerminal), VII (facial) and VIII (vestibulocochlear). Clinically, patients present with hearing loss, tinnitus, facial nerve palsies and symptoms of raised ICP such as vomiting, blurring of vision and headache. These symptoms are easily confused during early stages of pregnancy and demand thorough clinical examinations for brain tumour detection. The recurrence rates for CPA meningiomas and vestibular schwannomas are 15% and 0.3%–9.2%, respectively, after 5 years of gross total resection. However, regrowth of the residual tumour in schwannoma can occur up to 44%.^{4 5} Thus, long-term surveillance is warranted in both groups of patients.

There is no published level IA or IB management recommendations for intracranial neoplasms in pregnant women.⁶ Lynch et al suggested that if a patient presents acutely with sudden or severe neurological deficits, an emergency tumour-debulking surgery is recommended.³ The decision for neuro-oncological intervention demands multidisciplinary and patient-specific approaches in a pregnant woman. Factors to be considered include the type of lesion, location, neurological condition, the fetal gestational age, prognosis and the hazards of using a conservative strategy towards the pregnant woman.^6–8 Ideally, surgery should be avoided in the first and third trimesters to avoid risks of spontaneous abortion and preterm labour, respectively. If an elective surgery must be done, the second trimester is preferred as these risks are minimised.⁹

The retrosigmoid is the classic approach during resection of the CPA tumour. The best patient positioning for this approach is through Park-bench or alternatively the three-quarter prone. The retrosigmoid approach and Park-bench position will give the best operative window and comfort to the surgeon to arrive at the tumour. In the case of our pregnant patient, it is a blessing in disguise, as the Park-bench position avoided the abdominal aorta compression which can reduce uteroplacental supply to the fetus.^{10 11} Meanwhile, in lateral position, the ipsilateral shoulder of the patient will hinder the best operative field of the surgeon as it will restrict and limit the flexibility of the operative space to the surgeon to get to the tumour. Besides, lateral position is mainly for the tumour in the temporal region. Prone position is often used for lesions involving the posterior fossa, fourth and third ventricle or pineal region. Furthermore, it can also be used for posterior approaches to the cervical, thoracic and lumbar spine.¹¹

Complications of CPA tumour-debulking surgery include damage to the surrounding cranial nerves, causing bradycardia, arrhythmias, facial paralysis, risk of aspiration and hearing loss.⁴ As the CPA is a narrow space for the surgeons to operate, permissive hypotension can be applied to reduce risks of bleeding and cerebral oedema. Postoperative brainstem infarction may occur, causing loss of gag reflexes and death. Thus, our neurosurgeons were closely guided by IONM during the tumour debulking to avoid iatrogenic damage to the cranial nerves.

As an anaesthesiologist, the management of a pregnant patient who undergoes a craniotomy needs increased extra vigilance and considerations. Our patient was pregnant at first trimester and underwent tumour-debulking surgery in Park-bench position. Hence, we had to consider the safety of the mother and the fetus, perioperatively.

There are massive anatomical and physiological changes to the maternal cardiorespiratory, haematological and renal systems during pregnancy. As such, these present a great challenge to the anaesthesiologist. The focus is to provide an adequate cerebral and placental perfusion pressure to ensure viability of the brain and fetus. The CPP should be kept normotensive at a range of 50–70 mm Hg throughout surgery and ideally be guided by the ICP.^{9 12} To achieve this, our neurosurgeons inserted an EVD which was then connected to an ICP transducer to enable the neuroanaesthesiologist to monitor the patient’s CPP and ICP. In addition, it is important to provide optimal brain relaxation, and avoid fluctuations in the ICP and secondary pathological cerebral insults. These can be achieved by adequate intraoperative anaesthetic monitoring. Invasive devices such as arterial and central venous catheters (CVCs) are essential for precise intra-arterial BP monitoring and prompt management of intraoperative hypotension, hypertension, anaemia, hypoxaemia, hypercapnoea, acidosis, hypoglycaemia, hyperglycaemia and electrolyte imbalances. Park-bench position during suboccipital craniotomy for a CPA tumour-debulking surgery predisposes a patient to risks of venous air embolism (VAE) as the head is elevated above the heart. Thus, air can easily entrain via the open diploic veins into the systemic circulation to cause massive cardiopulmonary collapse. Air can be aspirated from the CVC at the neck as part of the management to decompress the right ventricle in patients with VAE.¹³ Hyperthermia of more than 37.5°C is avoided as it will increase cerebral metabolic rate of oxygen consumption.

Patient positioning during surgery is important to facilitate adequate exposure for the neurosurgeons to operate on. However, this can be complicated by a gravid uterus, especially patients who are at term pregnancy, which may cause splinting of the diaphragm to cause ventilation–perfusion mismatches, atelectasis, hypoxaemia and difficult ventilation.¹⁴ Patients at term pregnancy may also be at risk of aspiration pneumonitis due to increased intragastric pressure. Thus, a Ryle’s tube can be inserted to assist in decompressing the stomach. Placement of a wedge at the patient’s left hip may assist in reducing abdominal pressure onto the abdominal aorta and improve placental perfusion pressure. In patients who are positioned lateral or Park-bench, proper precaution should be taken when a cushion support is placed at the patient’s abdomen and pelvis to prevent injury to the abdomen, fetus, groin, kinking of femoral CVC and skin necrosis. We were fortunate that our patient was at the first trimester of her pregnancy. Thus, there were minimal disruptions faced on her positioning, ventilation and intra-abdominal pressures.

Special consideration should be undertaken with regard to pharmacological agents that are potentially teratotoxic.¹⁴ All intravenous and inhalational anaesthetic agents are safe to be used during pregnancy. In our patient, we used TCI of remifentanil and propofol as the choice of intraoperative anaesthetic management. This is due to the advantage that they do not significantly affect the values of BAEP, MEP and SSEP as compared with inhalational agents.^{15 16} They provide adequate cerebral relaxation and maintenance of CPP, prevent fluctuations in ICP and avoid the administration of muscle relaxants.¹² In addition, they are safe and provide adequate uteroplacental blood flow to the fetus. Mannitol, hypertonic saline 7.4% and furosemide should be used with caution as they can cause fetal dehydration. Antiepileptics, such as sodium valproate, are known to cause various congenital anomalies. However, levetiracetam has minimal effects on the growing fetus.¹⁷ Nevertheless, the mother should be well informed of the risks of drug interactions, which potentially cause miscarriages, preterm labour, intrauterine growth restrictions and birth defects.

Postoperatively, the patient should be nursed in the NCU for optimisation of haemodynamics and cerebral resuscitation.^{18 19} The fetal well-being should be managed by the obstetrician by monitoring the FHB and ultrasonography.²⁰ Any acute changes should be promptly managed and notified to the mother. An MRI of the brain is required to delineate the extent of postoperative intracerebral changes such as hydrocephalus, bleeding and infarction. Should these appear, an urgent neurosurgical intervention is indicated. The patient should be safely extubated once her haemodynamics and GCS are stable in addition to an intact cranial nerves function. Otherwise, an early tracheostomy is needed to facilitate weaning.

There are several novelties to be learnt from our patient. First, she had a rare huge right CPA meningioma during the first trimester of pregnancy. This was in stark contrast to knowledge that brain tumours are more common during the second and third trimesters. Second, she safely underwent a life-saving tumour-debulking surgery in a Park-bench position, which was carefully guided by BIS, BAEP, SSEP and MEP with the assistance of TCI remifentanil and propofol. Neuroanaesthesia for her was very challenging as we had to carefully titrate an ideal mean arterial pressure and CPP to ensure a viable fetus and brain perfusion in addition to preventing air entrainment and bleeding to the narrow CPA.

There are few limitations during our team’s management on this patient perioperatively. First, we failed to identify that she was pregnant during her first hospitalisation. Should we had noticed this, a cerebral MRI could had been performed rather than a CT scan to reduce radiation risks to the fetus. Any young, fertile female patients should be thoroughly assessed for her obstetric history. Second, we could have inserted a VPS during the first trimester while waiting for the fetus to thrive into the second trimester, after which complete tumour debulking can be undertaken. However, it risks of rapid tumour enlargement during the second trimester of pregnancy and onwards. This will compress onto the brainstem and cardiorespiratory centre, increasing the patient’s morbidity and mortality rate.

Despite these challenges, we were extremely grateful that the surgery was a success. This was attributed to the good communication and understanding between the multidisciplinary team involved in her management. We thoroughly discuss and consider the risks before proceeding for the craniotomy at the first trimester of pregnancy. Our patient delivered a healthy baby girl at term without any congenital defects, as we avoided teratotoxic agents throughout her pregnancy. Fortunately, as the HPE was a CPA meningioma, she did not necessitate a postoperative chemoradiotherapy, which may cause harm to her thriving fetus.

Patient’s perspective.

I am very grateful to be blessed with a chance to survive this ordeal and able to deliver my daughter safely. Initially I was thinking that I will not be able to live this long nor able to see her. But, thank God, I am surrounded by experienced doctors to save my life.

Learning points.

• A surge in oestrogen and progesterone levels during the second and third trimesters of pregnancy causes an increase in the size of intracranial tumours.

• Cerebellopontine angle (CPA) tumour is a rare intracranial neoplasm during pregnancies.

• Neuroanaesthesia for tumour debulking in a pregnant patient is extremely challenging, especially in patients during the first and third trimesters.

• The neuroanaesthetic aims during a CPA tumour debulking in pregnant patients are to ensure adequate cerebral and placental perfusion, minimise bleeding in the narrow surgical space and avoid teratogenicity agents to the growing fetus.

• Good communication, discussion and understanding among the multidisciplinary team are crucial to ensure excellent patient outcomes.

Ethics statements

Patient consent for publication

Obtained.