Cerebrovascular diseases are quite rare during pregnancy. Hemorrhagic cerebral accident is the third leading non-obstetric cause of mortality in pregnancy, with an incidence of 1 to 5 per 10,000 pregnancies.1 Half of these events are caused by subarachnoid hemorrhage (SAH) due to rupture of an arterial aneurysm or arteriovenous malformation. Aneurysmal SAH (aSAH) during pregnancy is associated with high mortality and morbidity, although large patient series are not available in recent literature.2
In 10% to 20% of all cases of SAH, no underlying vascular etiology is found and the source of hemorrhage remains unknown. Perimesencephalic SAH (P-SAH), a subset that accounts for approximately 50% of cryptogenic SAH, is characterized by the restriction of subarachnoid blood to the cisterns around the midbrain and is typically associated with a benign clinical course, excellent prognosis, and a low risk of rebleeding or other complications compared with aSAH.3,4
To our knowledge, only two cases of P-SAH during pregnancy have been described in the literature. Here, we report a case of P-SAH during pregnancy that was successfully diagnosed with magnetic resonance angiography (MRA) and resolved with conservative management. Patient has given her consent to publish the clinical information and figures in the journal.
The patient was a 34-year-old pregnant woman at 29 weeks’ gestation with acute-onset severe bilateral frontal headache, neck rigidity, and vomiting. There was no associated loss of consciousness, seizure activity, or focal neurologic symptoms and the patient was not responding to the common pain relief therapy (paracetamol). The patient’s medical history included an adrenocorticotropic hormone-secreting pituitary adenoma that was treated with radiotherapy but no history of headaches or hypertension. She was a non-smoker otherwise healthy pregnant women and she was not on any medication or drug except for thyroxine replacement therapy at the dose of 25 μg daily plus low dose aspirin for a high risk of preeclampsia in the first trimester. The pregnancy was uncomplicated.
Upon admission, the patient had normal blood pressure, was apyretic, alert and oriented, and had no focal neurological signs. MRA revealed hemorrhage in the prepontine and interpeduncular cisterns and hemosiderin deposition in the left superior vermian cistern with no vascular malformation or sources of bleeding. Moreover, there was diffuse angiospasm of the basilar artery and proximal tract of the left posterior cerebral artery and a crowded and swollen aspect of the superior cerebellar grooves (Fig. 1).
The patient was continuously monitored for vital parameters, and the fetus was monitored by ultrasound assessment of fetal well-being: fetal growth, amniotic fluid, and Doppler parameters were always found to be normal. The patient stopped low dose aspirin assumption and treatment with nimodipine (a calcium channel blocker, currently the drug of choice for angiospasm in SAH) was started at 60 mg/day (1.5 mL oral solution six times per day), decreased to 30 mg/day after the second MRA and continued until discharge. The second MRA, nine days after admission, showed the resolution of cerebellar edema and partial resolution of P-SAH and angiospasm. The patient was discharged 24 days after admission with mild headache treatable with paracetamol as needed.
Follow-up MRA was performed two months after discharge and showed complete resolution of angiospasm of the basilar artery and proximal tract of the left posterior cerebral artery (Fig. 2). The patient underwent a cesarean section (decided based on factors unrelated to P-SAH) at 39 weeks’ gestation without intra-operative or post-operative complications. The patient had no headache or other complications at her post-partum visits 1 and 3 months later.
The case described herein met the clinical and radiographic criteria for P-SAH, including: (1) center of hemorrhage located immediately anterior to the midbrain, with or without extension of blood to the anterior part of the ambient cistern or to the basal part of the Sylvian fissure; (2) no complete filling of the anterior interhemispheric fissure and no extension to the lateral Sylvian fissures, except for minute amounts of blood; and (3) absence of frank intraventricular hemorrhage.2
The etiology of P-SAH is generally unclear. In contrast with aSAH, the literature points to a non-arterial source for P-SAH. Different radiological studies have identified a primitive variant of venous drainage directly into the dural sinus instead of via the vein of Galen. Case reports suggest that venous hypertension may lead to P-SAH, directly or indirectly. Proposed direct mechanisms include stenosis of the vein of Galen at its junction with the straight sinus, cavernous sinus thrombosis, venulitis causing thrombosis, and spinal dural arteriovenous fistula. Case series have described perimesencephalic hemorrhage (PMH) after physical exertion5; the proposed pathophysiological substrate in these cases was physical exertion leading to venous hypertension, which increases intrathoracic pressure and thereby blocks venous return through the internal jugular vein. The subsequent increase in intracranial venous pressure can potentially elicit mechanical swelling of the intracranial veins and venous or capillary breakdown. An argument against this pathophysiological reasoning is that PMH has been described during pregnancy but never during childbirth, where childbirth is characterized as an event involving components of the Valsalva maneuver.2 Arterial causes associated with a perimesencephalic bleeding pattern other than aneurysm have only been described in case reports, such as rupture of a perforating artery, basilar artery dissection, cerebral cavernous malformation, and transient microaneurysm of the basilar artery. Except of intracranial aneurysm, none of these lesions have been reported in more than a few patients.6 Ultimately, a definitive explanation for PMH remains elusive. It is possible that physiologic changes associated with pregnancy including increased vascular pressure, connective tissue changes in cerebral vessels, or a hypercoagulable state could predispose patients to P-SAH.2
The overall management of P-SAH during pregnancy is challenging for several reasons. First, pregnancy imposes important limitations on diagnostic imaging and possible treatment options. Second, the low incidence of P-SAH in this population makes it difficult to establish evidence-based management guidelines. Third, optimal management requires assessment and consideration of both the mother and fetus individually.7 To our knowledge, only 2 other cases of P-SAH in pregnancy have been described in the literature, one in the first trimester and one in the third trimester.2 Diagnostic imaging in these cases included computed tomography angiography (CTA) with or without conventional four-vessel cerebral angiography. In our case, a multidisciplinary team including a neurologist, gynecologist, neurosurgeon, and neuroradiologist elected to monitor the patient using MRA and eventually postpone conventional angiography until after delivery, given that pregnancy is not a risk factor for P-SAH and given a low risk of hemorrhagic recurrence.8,9 Although digital subtraction angiography (DSA) remains the diagnostic standard for P-SAH10 with CTA a validated substitute, we propose MRA as an alternative in pregnant patients that minimizes radiation risk and allows close follow-up.
One other important consideration is the mode of delivery. In literature there was no evidence about the best mode of delivery, so the cesarean section was a choice of the patient and not a specific indication of multidisciplinary team.
In a recent review of 208 studies of P-SAH in the general population, short-term complications such as hydrocephalus or cranial nerve palsies were rare and usually transient, with the exception of acute symptomatic hydrocephalus necessitating treatment in 3% of patients. Long-term disability and mortality outcomes of P-SAH are excellent, especially compared to aSAH. Similarly, P-SAH during pregnancy seems to be associated with a favorable clinical course with no description of any complications in the literature.
Our report has various limitations: first of all, the retrospective design with very small sample (only one patient), then the short term follow up and the absence of follow up DSA to compare our result with the diagnostic standard for P-SAH. Further studies are needed to better inform the physiopathology, clinical course, diagnosis, and therapeutic management of P-SAH during pregnancy.
Maurizia Gatto, Alessandra Giocolano, Salvatore D’Oria, Filippo Tamma, Maurizio Guido, and Maria Annunziata Gentile were responsible for clinical management. Stefania Ruggieri, Chiara Taccaliti, Domenico Caringella were involved in manuscript preparation.
All authors contributed to and approved the final version of the manuscript.
Conflicts of Interest
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Edited By Yang Pan
How to cite this article: Ruggieri S, Gatto M, Gentile M A, D’Oria S, Tamma F, Caringella D, Giocolano A, Taccaliti C, Guido M. Perimesencephalic Subarachnoid Hemorrhage in Pregnancy: A Case Report. Maternal Fetal Med 2022;4(4):290–292. doi: 10.1097/FM9.0000000000000107.