Challenging Clinical Case

Pregnancy Complicated By a Symptomatic Posterior Fossa Arteriovenous Malformation – Clinical Decision Making and Dilemmas: A Case Report

By Shobana Rajan, MD; Christopher J. Yontz, DO; Gargi Banerjee, MD; and Karen Steckner, MD
Cleveland Clinic Foundation

Corresponding author: Shobana Rajan, MD

INTRODUCTION
Pregnancy complicated by intracranial arteriovenous malformation (AVM) presents a challenging clinical scenario due to the intracranial pathology superimposed on the hemodynamic alterations of pregnancy. Risks imposed on the fetus by imaging, procedures and medications for the management of this critical situation further add to the complexity of the situation. Risks and benefits of various obstetric and anesthetic management strategies, fetal and maternal monitoring, and postoperative care plans must be weighed. Most troublesome is the fact that these cases are relatively uncommon and thereby under documented. As a result, there is lack of clinical consensus and effective guidelines to direct management. We discuss the decision-making process involved in the care of a 37-year-old primigravida at 26 weeks gestational age presenting with a symptomatic AVM.

We obtained written HIPAA authorization (permission) from the patient for submission of the clinical case report for potential publication.

CASE DESCRIPTION
The patient presented with an 11-week history of dizziness, nausea, blurred vision, head ache and neck stiffness. Past medical history was insignificant. Subtle diplopia and horizontal nystagmus on right lateral gaze were revealed on examination. MRI/MRA was suggestive of an AVM producing a mass effect on the right cerebellum and brainstem.  Angiography revealed Borden II/ Cognard IIb Dural arteriovenous fistula (AVF) supplied by the right inferolateral trunk, marginal tentorial artery and middle meningeal artery, to the right tentorial venous sinus.

Management options, with accompanying risks and benefits considered, were discussed at length. A Cesarean delivery was planned at 30 weeks of gestation to avoid the risk of any untoward complication necessitating an unplanned emergent intervention such as embolization or open cranial resection during pregnancy leading to fetal and maternal harm. Subsequent to delivery, angiographic embolization of the AVM was planned for the following day. The patient was kept in the hospital under close monitoring.  Steroids and magnesium sulfate were administered antenatally to promote lung maturity and provide neuroprotection respectively. 

Literature regarding the mode of anesthesia in such a situation was inconclusive. Options included spinal, epidural and general anesthesia. Neuraxial anesthesia would prevent hypertension and therefore reduce the risk of AVM rupture. Spinal anesthesia was decided against due to the risk of sudden decrease in intracranial pressure (ICP) with dural puncture, risking AMV rupture or brainstem herniation. Also, a post-dural puncture headache would produce a confusing clinical picture. Epidural anesthesia was strongly considered, however the need for anticoagulation during the subsequent angiographic embolization, the risk of inadvertent dural puncture and brainstem herniation, and the possibility of recalcitrant hypotension were deterrents that led us to choose general anesthesia as the safest approach.

The patient was premedicated with sodium citrate, metoclopramide, and metoprolol. She was positioned supine with left uterine displacement. Standard American Society of Anesthesiologists monitors were applied. A pre-induction arterial line was placed under local anesthesia. Minimal sedation with midazolam and fentanyl aided in the placement of an external subdural bolt (Figure 1) under local anesthesia for ICP monitoring with a Camino monitor (Figure 2).

Fig 1
Figure 1. Subdural bolt placement for ICP monitoring

Fig 2
Figure 2. Camino monitor

The initial ICP was 10 mmHg and a goal of 10-20 mmHg was established. Esmolol boluses were used for strict hemodynamic control. Uneventful rapid sequence induction (RSI) was achieved with fentanyl, lidocaine, Propofol, succinylcholine and additional esmolol boluses and her airway was secured with a Glidescope. Anesthesia was maintained with a Propofol infusion and less than 0.5 MAC of sevoflurane to prevent a rise in ICP and to promote uterine relaxation for delivery. Cesarean delivery was performed with minimal fluctuations in hemodynamics or ICP. The fetus was delivered five minutes after incision. Pediatric intensivists were immediately available for neonatal resuscitation, however the neonate only required oxygen via nasal cannula.

After delivery, the patient was paralyzed with rocuronium and switched to a total intravenous anesthetic with Propofol and remifentanilto prevent uterine atony from volatile anesthetics and to allow for smooth emergence and extubation. Pitocin was administered for uterine tone. Dexamethasone and ondansetron were given for postoperative nausea and vomiting (PONV) prevention. Neuromuscular blockade was reversed and she quickly emerged after discontinuation of TIVA with minimal coughing. Her ICP was maintained under 20mmHg except during extubation when it transiently increased to 28 mmHg. She was taken to the post-anesthesia care unit where her ICP settled to 6 mmHg postoperatively. Multimodal analgesia postoperatively included transversus abdominis plane (TAP) block, ketorolac, acetaminophen and intermittent fentanyl.

Angiography and embolization of the AVM was planned for postoperative day one. Anesthetic goals were strict control of hemodynamics and ICP once again. An abdominal uterus necessitated RSI. Elective Glidescope intubation was again accomplished without difficulty. Anesthesia was maintained with remifentanil and sevoflurane with non-depolarizing muscle relaxants for paralysis. Hemodynamic parameters and ICP were kept within the same target ranges. Neuromuscular blockade was reversed, and the patient was extubated uneventfully.

DISCUSSION
This case presented multiple clinical dilemmas to the care teams involved:

  1. Should the pregnancy be terminated? If not, should it progress to term?
  2. Should neurosurgical intervention proceed prior to delivery?
  3. At what gestational age should preterm delivery be performed to get the best possible outcome for the fetus?
  4. What is the safest mode of delivery in parturient with intracranial AVM?
  5. What mode of anesthesia should be instituted?

Answers to the above questions may vary with institutional practice and clinical presentation. Our patient was symptomatic with a Borden ll/Cognard llb dural AVF at a precarious location. Abnormal vessels were identified on either side of the pons, creating a mass effect on the right cerebellar hemisphere and right side of the brainstem.

We were concerned that hemorrhage, if occurred, was likely to be unannounced. Treatment during pregnancy was also fraught with complications such as the need for surgery following an attempted embolization, risk of large radiation exposure to the fetus, and difficulty in management of a high output cardiac state during surgery. An emergent delivery under duress would incur greater fetal/neonatal harm. We concluded that delaying intervention and allowing the pregnancy to progress carried a very high risk of maternal and fetal harm compared to expediting the delivery and proceeding with AVM treatment. Hence, the pregnancy was continued under close observation until 30 weeks gestational age, followed by Cesarean delivery and embolization of AVM the following day. This timeline was strategically chosen to allow for hemodynamic recuperation and to avoid the anticoagulation needed for embolization for 24 hours post Cesarean delivery.

A review of literature brings to light one study which reported pregnancy related hemorrhage from aneurysms and AVMs that attributed 5-12% of all maternal deaths during pregnancy and 17% of fetal mortality to AVM or aneurysmal complications (1,2). Another study reports 21 ischemic strokes and 11 hemorrhagic strokes among 58,429 deliveries and 4 out of 11 cases resulted from AVM rupture (3). A recent study, which is one of the largest cohorts describing hemorrhage risk of brain AVM during pregnancy from Johns Hopkins, found an overall annual hemorrhagic risk of 1.34%, which was 1.30% during the nonpregnant period and 5.7% during pregnancy and puerperium (4).
Xiani et. al. retrospectively reviewed 67 cases of AVM with pregnancy and concluded that hemorrhage risk of AVM in pregnancy is low. Vaginal deliveries seemed not to increase the hemorrhage risk in unknown AVM gravidas. They did not recommend prophylactic surgical resection of unruptured AVM for women considering pregnancy (5).

However, some authors suggest that early surgical intervention of AVM before delivery lead to improved maternal and fetal prognosis (6,7). Fukuda K et. al. described pregnancy and delivery management in nine patients with AVM. They suggest a removal of AVM during pregnancy in cases with immature fetus and low operative risk and a modified vaginal delivery/Cesarean section prior to AVM management in cases of mature fetus or late pregnancy (8).

A Cesarean delivery was unanimously agreed upon.  However, the mode of anesthesia was up for debate. Epidural anesthesia was a plausible option as it offered the advantage of keeping the blood pressure low, thereby guarding against a potential AVM rupture. It also would safely accommodate the auto transfusion after removal of the placenta, in addition to providing adequate postoperative analgesia.

Carvalho CS et at. reported a case in 2013 where a pregnant patient, healthy prior to pregnancy, with a history of SAH at 22-week gestation, was allowed to progress to 39-week of gestation and then taken for Cesarean section under Epidural anesthesia. Their rationale for using an neuraxial block over general anesthesia was the hemodynamic advantage and the reason for favoring epidural over spinal was the gradual onset of sympathetic blockade and the existence of compensating phenomenon with the former (9). However, our concern was an inadvertent dural puncture which could cause ICP to plummet, thereby causing a dramatic decrease in intramural pressure.

Lastly, the stability of the blood patch if needed would also be at stake given the high probability of anticoagulation during the embolization scheduled the following day. In our minds, a secure airway and better control of hemodynamic parameters offered by general anesthesia outweighed the blood pressure lowering virtues of epidural anesthesia.

CONCLUSION
Pregnancy with symptomatic intracranial AVM poses a clinical challenge and demands a multidisciplinary approach. We decided upon preterm delivery at 30 weeks gestational age under general anesthesia and AVM embolization the following day. Our patient’s hemodynamics and ICP were closely monitored throughout her stay and were kept within our target ranges. Maternal and fetal outcome were excellent. However, a lack of guidelines to direct management, questions regarding timing of neurosurgical intervention relative to delivery, and the choice of anesthetic management remain unanswered and call for larger studies.

REFERENCES

  1. Dias MS and Shaker LN. Intracranial hemorrhage from aneurysm and arteriovenous malformations during pregnancy and the puerperium. Neurosurgery 1990; 27(6): 855-65
  2. Finnerty JJ, Chisholm CA, Chapple H, Login IS, Pinkerton JV. Cerebralarteriovenous malformations in pregnancy: presentation and neurological, obstetric and ethical significance. Am J Obstet Gynecol. 1999; 181: 296-303
  3. Skidmore FM, Williams LS, Fradkin KD, Alonso RJ, Biller J. Presentation, etiology and outcome of stroke in pregnancy and puerperium. J Stroke Cerebrovasc Dis. 2001; 10: 1-10
  4. Porras JL, Yang W, Philadelphia E et al. Hemorrhage risk of brain ateriovenous malformations during pregnancy and pureperium in a North American cohort. Stroke 2017; 48:1507-13
  5. Xianli Lv, Wei Li, Hongwei He, Jiang C, Youxiang Li. Known and unknown arteriovenous malformations in pregnancies: hemorrhage risk and influence of obstetric management. Neuroradiol J. 2017; 30(5): 437- 41
  6. Robbinson JL, Hall CS, Sedzimir CB, Arteriovenous malformations, aneurysms and pregnancy. J Neurosurg 1974; 41(1): 63-70
  7. Tridevi RA, Kirkpatrick PJ: Arteriovenous malformations of the cerebral circulation that rupture in pregnancy. JObstetGynaecol 2003; 23 (5): 484-9.
  8. Fakuda K, Hamano E, Nakajima N, et al. Pregnancy and delivery management in patients with arteriovenous malformations: a single Centre experience. Neurol Med Chir(Tokyo). 2013; 53(8): 565-70.
  9. Carvalho CS, Resenda F, Centeno MJ, Ribeiro I, Moriera J. Anesthestic approach of pregnant woman with cerebral arteriovenous malformation and subarachnoid hemorrhage during pregnancy: a case report. Braz J Anesthesiol 2013; 63:223-6

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