Neurosurgical interventions during pregnancy

Summary

Neurosurgical illnesses or disorders are rare in pregnancy. Vascular pathologies, intracranial tumors, traumatic brain injury or disc herniation are the most common. Recognition of clinical signs, diagnosis and follow-up treatments can be difficult to manage regarding pregnancy. Vomiting or headache are typical symptoms for both pregnancy as well for increased intracranial pressure. As part of the diagnosis, we should avoid excess usage of radiological examinations. Therapeutic guidelines have not been clearly established; therefore, they are based only on retrospective studies or case reports. In our review article, we present the most common neurosurgical pathologies in pregnancy and their treatment.

Keywords:

pregnancy – neurosurgery in pregnancy – intracranial pathologies

This is an unauthorised machine translation into English made using the DeepL Translate Pro translator. The editors do not guarantee that the content of the article corresponds fully to the original language version.

 

Introduction

Neurosurgical diseases in pregnancy are rare. Because of their severity (especially craniocerebral injuries, tumors, and vascular pathology), they are among the leading causes of indirect pregnancy mortality [1]. Physiological changes associated with pregnancy, such as increased circulating volume, hypercoagulable state, or hormonal changes, can worsen the clinical course of intracranial lesions [2] or promote intervertebral disc protrusion in the case of ligamentous laxity along the spine [3]. Clinical presentation, imaging and actual management remain a challenge and should always be performed within a multidisciplinary team. At present, there are as yet no precise recommendations on how individual pathologies should be managed [4]. The aim of this paper is to give an overview of the issue, documented by several clinical examples.

Pregnancy is not a risk factor for neurosurgical pathologies. However, physiological changes in pregnancy may worsen the clinical course, diagnosis and treatment of these pathologies. These include cerebrovascular pathologies, severe craniocerebral injuries, intracranial tumors, and spondylogenic problems in intervertebral disc prolapse or lumbar stenosis [5,6]. The natural history of these pathologies, risk factors, and the effect of pregnancy on these diseases have not been described for mostly small cohorts of patients. It is also not possible to conduct a randomized trial in this group of patients [7-9]. At the same time, clinical symptoms of increased intracranial pressure, such as vomiting, nausea or headache, are common in ongoing pregnancy. Thus, the pathology may not be immediately diagnosed [4].

Another problem is the use of imaging methods, which is limited with regard to maternal exposure and possible fetal damage [7]. The literature indicates that acutely performed CT with a dose below 50 mGy does not have a negative effect on the developing fetus. According to the American College of Radiology, a single radiation scan does not increase the risk to the fetus, but the use of uterine shielding is still recommended [5]. In its recommendations, the American Society of Obstetricians and Gynecologists states that if a CT scan provides a greater benefit than the risk to the mother or fetus, the scan is indicated. For a native head CT, the estimated dose to the fetus is given as 0.001-0.01 mGy and is one of the low-dose examinations. The effect depends, of course, on the stage of pregnancy; there is a risk of fetal death before implantation, developmental abnormalities in the first weeks, and intellectual disorders later. However, all these risks are related to the higher ionization dose (50-280 mGy) [10].

MRI examination is recommended in the planning of neurosurgery and is not contraindicated in pregnancy [2]. It has not been shown to have a negative effect in either the first or subsequent trimesters. The use of the contrast agent gadolinium is controversial, as this substance crosses the placenta. Gadolinium is present in the amniotic fluid, the substance is thus repeatedly ingested and excreted by the fetus and recirculated in its body. It is therefore not possible to determine the exact time of exposure. Thus, the use of gadolinium should only be indicated in narrowly selected cases in which the benefit of testing outweighs the potential risks to the fetus or mother. Breastfeeding should not be discontinued after gadolinium administration as no adverse effect on the newborn has been demonstrated. It is reported that less than 1 % is absorbed by the gastrointestinal tract of the infant. In general, the use of non-ionizing examinations is recommended if the patient's condition permits [10].

Treatment decisions should always be made by a multidisciplinary team, which should also take into account the wishes of the patient and family members. This must include an examination of the mother and the foetus and an assessment of its viability. It is necessary to reflect potential haemodynamic changes during surgery that may affect placental or fetal perfusion [11]. Another factor is the stage of pregnancy. In the third trimester, we usually opt for induced labour with neurosurgical intervention; in the first two trimesters, it is a matter of consideration whether not to terminate the pregnancy due to the potential risk to the mother and therefore the fetus. However, we always base our assessment on an individual basis [7].

Neurosurgical procedures in pregnancy are usually performed under general anaesthesia in the presence of a gynaecologist with direct monitoring of fetal vital signs. According to the literature, approximately 9% of surgeries are associated with preterm delivery. The supine position is not recommended, as it may cause compression of the inferior vena cava, arterial hypotension and placental hypoperfusion. If possible due to the location of the lesion, we choose the lateral position [9].

Gadol et al. present 34 patients with various intracranial pathologies who underwent neurosurgery. Most of the patients tolerated the procedure without complications and without any adverse effect on pregnancy. In the case of deterioration of the maternal or fetal condition, these were patients already admitted in critical condition [7].

 

Cerebrovascular pathology

Intracranial haemorrhage (ICH) accounts for 10% of deaths in pregnant women [9]. The most risky periods are the third trimester and puerperium [12]. Risk factors include pre-eclampsia, eclampsia, changes in coagulation parameters in pregnancy, thrombocytopenia, gestational hypertension, blood transfusions, HELLP syndrome (hemolysis, elevated liver enzymes, low platelet count) or postpartum infections [7]. The risk of ICH is up to 2.73× higher in gestational hypertension and up to 9.23× higher in pre-eclampsia and eclampsia [13]. According to the available literature, the incidence of vascular pathologies in pregnant women is very low: 0.01-0.05%. The most frequently encountered are arterio-venous malformation (AVM), aneurysm or Moya Moya disease. The risk of bleeding from an unruptured AVM is in a similar range to that of non-pregnant women -⁠ 3.5% in pregnancy per year vs. 3.1%. Conversely, in the case of pre-existing bleeding, the risk of further bleeding increases to 27% [12]. AVM bleeding in pregnancy has a mortality rate of 5-12% in the mother and 17% in the fetus [14]. It is not feasible to keep patients hypotensive during therapy because of possible placental hypoperfusion [12]. Treatment of the malformation depends on the current condition. For progressive neurological deterioration, we choose an active approach, which continues with cesarean section in the third trimester. In the first and second trimesters, it depends on the condition of the mother and the indication of the obstetrician-gynecologist [14,15].

The incidence of spontaneous aneurysmal subarachnoid haemorrhage (SAH) is 5 times higher than in non-pregnant women [9]. It causes approximately 5% of deaths among pregnant women. The risk of rupture increases with advancing trimesters, from 6% in the first to 55% in the last trimester [5]. This increase in the risk of rupture towards the end of pregnancy is related to ongoing changes in pregnancy -⁠ hormonal influence on the vessel wall, further increase in circulating volume, and thus a higher risk of growth, but also of aneurysm rupture [12]. Surprisingly, 90% of ruptures occur in pregnancy, only 2% during labor itself and 8% in puerperium [5,11]. The diagnosis is performed by standard native CT. A single CTA does not adversely affect the developing fetus, but despite this, there is a small risk of developing hypothyroidism as the iodine contrast agent can cross the placenta. If this examination is indicated, the fetus must be shielded during the examination. MR examination is not suitable for the detection of fresh blood, but can be used to assess the extent of bleeding when repeat imaging is necessary [12]. Ruptured or growing aneurysms are recommended to be treated neurosurgically even during pregnancy [9].

In ruptured aneurysms presenting with SAH in the acute state, we proceed with treatment as in a non-pregnant patient. In the first stage, we choose to treat the aneurysm. The situation is different if the rupture occurs during delivery. In this case, the baby is delivered first and then the aneurysm is treated neurosurgically. Ng and Kitchen divided the management for SAH therapy into three groups according to the progress of pregnancy. In case of pregnancy up to 26 weeks, maternal health is the first priority, after 34 weeks, a caesarean section is recommended to save the life of the mother and fetus, followed by treatment of the aneurysm. The period between these two periods should be strictly individualised. In a stable patient, surgery can be performed under general anaesthesia with fetal monitoring, in an unstable patient usually in conjunction with caesarean section [5].

For unruptured aneurysms, Nussbaum et al. divide therapy according to size [16]. Small and non-growing ones can only be observed with regular follow-up on MRA (at least two follow-up views during pregnancy) and larger or growing ones can be actively addressed surgically or endovascularly. However, recent studies provide data that small aneurysms may have a greater tendency to rupture [16]. Thus, in the future, active management of even unruptured aneurysms during pregnancy may be approached more frequently. It is reported that there is no difference between clip and coil. The former treatment method involves prolonged hospitalization, whereas the latter involves exposure to radiation. In the literature we find one case in which a pregnant woman was treated with a flow-diverter after insufficient embolization of the sac [16].

Unfortunately, the method and timing of delivery in partially treated or untreated vascular lesions not associated with SAH is not clearly defined in the literature and it is recommended to proceed on an individual basis. Some papers have reported that there is no higher risk of intracranial bleeding in normal vaginal delivery compared to cesarean section [9], but most papers recommend cesarean section [11].

During pregnancy, a hypercoagulable state develops physiologically as a prevention of excessive bleeding during labor. Thus, there is a predisposition for the development of thrombosis of the rafts or cortical veins. Most often, this pathology is described in the puerperium. Low molecular weight heparin remains the treatment of choice [12].

In the indication for neurosurgical treatment of vascular lesions, the patient's condition, pregnancy risk and fetal viability should always be assessed. In case of higher risk of pregnancy, a procedure followed by delivery or neurointerventional treatment should be chosen. In general, it is difficult to decide whether a vascular lesion is at risk or not, as pregnancy has its own specificities and the natural evolution of these lesions and their behaviour have not yet been described [9].

 

Brain tumours

In general, pregnancy does not predict a higher incidence of intracranial tumours. In hormone-dependent meningiomas, pregnancy may only accelerate the growth of the lesion [4,6,17]. In pregnancy, meningiomas, gliomas, adenomas and neurinomas are most commonly encountered [1,8]. Intracranial lesions are difficult to diagnose aside from clinical signs and imaging. In the acute phase, when there are signs of intracranial hypertension, we opt for native CT with shadowing of the abdominal and pelvic landscape, trying to avoid the use of contrast agent. For better imaging, we use MRI, which is not contraindicated in pregnancy. Controversial remains the administration of the contrast agent gadolinium, for which the opinions of the papers are divided. Gravidity is not a clear contraindication for its administration, but it should only be used in narrowly indicated cases, see also above [2,11].

For benign tumours, we wait to operate until after delivery, except for lesions in the elocutaneous regions, which cause irreversible neurological deficit by their presence and possible further growth. We are also more active in case of acute deterioration of the clinical condition [5,17]. In highly malignant tumors, surgical cytoreduction is recommended as soon as possible and regardless of the progress of pregnancy. In case of radiotherapy, it is advisable to terminate the pregnancy in the first trimester and use special shields for fetal protection in the later stages. Chemotherapy is usually started after delivery, after artificial lactation arrest [5].

A special group of tumors in pregnancy are meningiomas. Although their incidence does not increase during pregnancy, pregnancy affects these lesions [8]. Due to the increased amount of circulating hormones in the blood, there is a significant acceleration of growth. This can lead to the development of acute neurological deficits and endangerment of the mother and fetus, respectively. In general, if possible, neurosurgery should be delayed until after delivery. If there is a rapid deteroriation of the condition and the neurological deficit could remain irreversible, we opt for an active neurosurgical approach. We make decisions based on the stage of pregnancy. Laviv et al. state that in cases up to 26 weeks of gestation, it is advisable to perform an acute craniotomy and continue the pregnancy; on the other hand, after 37 weeks, we opt for delivery first and then surgery. The critical period is between 26-37 weeks, we proceed according to the viability of the fetus and according to the urgency of the clinical condition of the mother. Delivery is usually performed by caesarean section, due to the possibility of further increase in intracranial pressure during vaginal delivery. In the management of increased intracranial pressure, the use of diuretics is not recommended because of the possible decrease in the circulating volume in the mother and, therefore, the development of hypoperfusion in the placenta [18]. According to the literature, meningiomas in pregnant women are mostly located at the base of the skull, most often in the parasellar region with vascular supply from the anterior circulation. The question remains whether this site is predisposing, or whether there is only an earlier clinical manifestation due to the surrounding structures located at the base. Compared to the general population, there is a marked significant difference in the deposition at the skull base in pregnant women [8]. The most common clinical presentation tends to be visual disturbances, behavioural changes or hemiparesis/hemiplegia. Meningeomas are usually diagnosed during the second and third trimesters and a reduction in size after pregnancy has been described [18]. With subsequent pregnancies, meningiomas may again enlarge, so treatment before the next pregnancy is advisable. Previously, the hormone progesterone was thought to play a major role in accelerating meningioma growth. However, recent studies show that prolactin plays a major role. The hormone produced by the pituitary gland influences the tumor tissue via branches of the internal carotid artery, probably by osmoregulatory mechanisms [8].

Gliomas, especially high-grade ones that are diagnosed in pregnancy, present a medical dilemma. Due to their rapid growth, early neurosurgical cytoreduction and subsequent initiation of radiotherapy and chemotherapy are essential. However, all these treatments have a negative impact on the developing foetus, especially the latter two. The decision on the therapeutic course of action always remains in the hands of the multidisciplinary team and also in the hands of the patient herself and family members [17]. Pregnancy per se does not increase the incidence of gliomas, but it can significantly worsen the course of the disease. There is an increase in tumour volume, dedifferentiation of tumour cells and recurrence of the disease. The development of clinical symptoms is also more rapid [2,19,20]. Most tumors are diagnosed in the third and second trimesters, less frequently in the first [20]. In the case of neurosurgery, it is possible to operate during pregnancy with close monitoring of the mother and fetus, whereas it is recommended to start radiotherapy and chemotherapy after pregnancy has ended [1]. In most cases, we try to postpone the procedure to the second or third trimester because of fetal maturation. In the third trimester, if the fetal condition permits, a caesarean section is preferred first, followed by neurosurgery. However, it is advisable to keep in mind the increased risk of bleeding during the third trimester due to further increase in circulating volume [2]. In women with a history of glial tumor who are still planning pregnancy, it is recommended to wait at least 3 weeks after completion of all therapy and to perform MRI scans periodically during pregnancy. However, this recommendation is based on only one available case report [21].

Again, metastases are very rarely diagnosed in pregnancy [4]. The most common metastases are lung cancer, breast cancer or melanoma. We try to postpone neurosurgical intervention until the second or third trimester. The first trimester is very risky for the fetus and in case of surgery followed by chemotherapy or radiotherapy, it is advisable to discuss with the mother all possible side effects of the treatment and to consider the planned termination of the pregnancy. In the period between 13 and 26 weeks, the urgency of the procedure is again to be considered. Around the 26th week, the option of caesarean section and subsequent initiation of maternal therapy is offered. In case of surgical necessity, we opt for the position of the mother on her side with close fetal monitoring [22].

As for possible radiotherapy, we prefer stereotactic surgery (SRS) to whole brain radiation therapy (WBRT) with shielding to minimize uterine and fetal exposure to radiation [22]. The main adverse effects of the use of radiotherapy in pregnancy include fetal death, malformation, mental or growth retardation, as well as induction of cancer. The dose during SRS treatment can be adjusted so that, although it does not meet the therapeutic optimum, it is sufficient to stop the growth of the tumor, which can be surgically removed after termination of pregnancy. This will provide a balance between the need for oncological treatment and potential adverse effects on the fetus [23].

In general, the therapeutic management of each pregnant patient with CNS cancer should be decided by a multidisciplinary team consisting of an obstetrician-gynaecologist, anaesthesiologist, neonatologist, oncologist and neurosurgeon [22].

 

Craniocerebral injuries

Craniocerebral trauma (traumatic brain injury; TBI) is a leading non-pregnancy cause of mortality [24-26]. It is most commonly caused by a car accident or domestic violence. Management is usually more dramatic compared to the general population as we fight not only for the survival of the mother but also the fetus. Maternal and subsequently fetal hypoxia, placental abruption, premature delivery or Rh immunization may occur [27]. We cannot apply the recommendations we have in the general adult population. The treatment always involves a multidisciplinary team consisting of a neurosurgeon, obstetrician, neonatologist and anaesthesiologist [25].

Timing of neurosurgery is always difficult. In the first and second trimesters, we focus treatment primarily on the mother and therefore follow standard procedures as for non-pregnant patients [26]. Although the risk of spontaneous abortion (15-20%) and congenital malformations (3-5%) is highest during this period when general anaesthesia is used [25], by saving the mother we are able to save the developing fetus [26]. In indicated cases, the decision to terminate the pregnancy may be made [6]. In viable fetuses (above 24 weeks), we choose first to deliver under general anaesthesia and then to perform neurosurgery [25].

In general, when managing TBI in pregnant women, we should first assess the risks and benefits to the mother and fetus. Next, provide emergency resuscitative care to the mother, perform a follow-up CT scan to assess intracranial injuries and determine fetal viability. Based on the clinical status of the mother and the CT findings, then choose the eventual neurosurgical intervention. After providing initial treatment, it is then important to monitor basic vital signs, especially oxygenation to prevent fetal hypoxia. Filippo et al. describe a treatment approach based on consideration of physiological changes in pregnancy, risks to the mother and fetus, management of secondary insults, and of course the mother's wishes. Their work illustrates the different schemes and thus provides at least partial recommendations on how to proceed [26].

 

Intervertebral disc protrusion

Back pain is a very common symptom in pregnancy, with an incidence of 54-76% [3]. They usually arise in association with physiological changes during pregnancy, such as uterine expansion, accentuation of lumbar lordosis, weight gain, etc. All these changes then increase the mechanical stress acting on the whole spine, especially on the lumbar region. In addition, during the third trimester, the ligaments of the pelvis and spine are loosened by the action of relaxin, thus increasing the risk of possible intervertebral disc prolapse [3,28]. The incidence of problems associated with radiculopathy due to disc prolapse is around 1 case per 10,000 pregnant women, and less than 15% of them lead to severe neurological deficit [29]. Performing an MRI of the spine, which is necessary for the final diagnosis, is not contraindicated [30]. Conservative management is usually chosen as initial therapy [31]. Rest, rehabilitation of the lumbar spine and, among the drugs, acetaminophen, in our case paracetamol, are recommended [3]. The use of non-steroidal anti-inflammatory drugs should be avoided as they may cause miscarriage or various fetal developmental defects. Opiates are also not recommended due to the possibility of birth defects. They are also associated with attenuation of the respiratory centre [28]. Regional anaesthesia should be used during surgery because of the lower exposure of the fetus to anaesthetic drugs compared to general anaesthesia. Fetal monitoring is performed in fetuses older than 25 weeks. The position is chosen according to the stage of pregnancy; in the first and early second trimester, surgery can be performed on the abdomen. At the end of the second and third trimesters, we prefer the lateral position. The indication and the surgical procedure should always be performed under the guidance of an experienced multidisciplinary team. The American College of Obstetricians and Gynecologists (ACOG) recommends delaying intervention until after delivery or at least into the second trimester. In the case of acute and worsening neurological deficit, surgery is always indicated immediately according to the following procedure. In pregnancies up to 26 weeks, we opt primarily for a neurosurgical approach and continuation of the pregnancy; from 34 weeks onwards, it is advisable to deliver the baby first by caesarean section under general anaesthesia if fetal viability allows, and then follow up with neurosurgery. The period between 26 and 34 weeks is the most critical and is guided by the severity of the neurological deficit and the gynecologist's statement [3]. In women who have symptomatic intervertebral disc prolapse that is not yet indicated for intervention, cesarean delivery is recommended [31]. Kim et al. describe the successful use of endoscopic removal of an intervertebral disc prolapse in a pregnant woman with cauda equina syndrome [30].

 

Other less common pathologies

In Chiari malformation, pregnancy does not carry a higher risk of herniation of the cerebellar tonsils. For symptomatic patients, cesarean section under general anesthesia or assisted vaginal delivery is recommended. Decompressive surgery is indicated only in case of progression of neurological symptoms [32].

 

Conclusion

Pregnancy is not a risk factor for a higher incidence of neurosurgical diagnoses. However, due to the physiological changes associated with pregnancy, their clinical course worsens. The entire management, from clinical symptoms through diagnosis and therapy, is difficult. There are no clearly defined procedures in the literature and recommendations are usually based on published small series or single case reports. An individualised approach with an assessment of all possible risks to mother and foetus within a multidisciplinary team remains essential.

 

Conflict of interest

The authors declare that they have no conflict of interest in relation to the subject of the study.