Hereditary haemorrhagic telangiectasia and neuraxial anaesthesia in pregnancy: when should magnetic resonance imaging be performed?

Hereditary haemorrhagic telangiectasia (HHT) is a genetic disorder resulting in the formation of cutaneous telangiectasias and visceral arteriovenous malformations (AVMs) in the lung (40%), liver (75%), gastrointestinal tract (20%), brain (10–20%) and the spine (<1%). It affects approximately 1 in 5000 people worldwide [1].

In pregnancy, HHT is a high‐risk condition due to the possibility of severe, life‐threatening complications precipitated by the physiological and hormonal changes of pregnancy. The overall risk of complications is 1%. However, in the undiagnosed or untreated obstetric patient, the risk of non‐fatal complications may be as high as 17% usually from pulmonary AVMs [1].

The Second International HHT Guidelines state that there is no evidence for routine screening for spinal AVMs, as the risk of complications during epidural anaesthesia are considered “unsubstantiated and only theoretical” [1]. However, these guidelines do not differentiate between spinal and epidural anaesthesia despite the anatomical differences between the two. Spinal AVMs in HHT are usually located in the intradural space meaning spinal anaesthesia carries a higher risk of rupturing a spinal AVM [2]. As the risk is associated with the dural puncture itself, the same risk would be considered for other cerebrospinal fluid (CSF)‐identifying techniques, such as dural puncture epidural (DPE) or combined spinal‐epidural (CSE). A recent case report describes the diagnosis of an asymptomatic lumbar spinal AVM on magnetic resonance imaging (MRI) conducted for screening prior to caesarean delivery (CD), informing the decision to proceed with general anaesthesia (GA) [3]. Paralysis and cord compression following rupture of spinal AVMs as a result of neuraxial techniques in patients without HHT has been described [4, 5, 6]. These cases highlight the benefits of screening given the potential catastrophic implications if missed.

General anaesthesia is considered high‐risk for many patients with HHT due to the potential for pulmonary involvement and the associated implications of positive pressure ventilation and the sympathetic response to laryngoscopy. However, the lack of distinction between spinal and epidural anaesthesia in the current guidelines makes them insufficient to assist anaesthetists with decision‐making. We advocate routine MRI of the spine for all patients with HHT for whom CD is planned or where there is a high likelihood of requiring neuraxial anaesthesia or analgesia for delivery.

The optimal timing of the MRI and the validity of pre‐pregnancy imaging are uncertain in the assessment of the pregnant patient with HHT. The physiological changes of pregnancy, such as increased cardiac output, reduced peripheral vascular resistance and elevated progesterone levels are thought to exacerbate existing shunting lesions in abnormal vascular beds in HHT [7]. It is also recognised that the complications of HHT during pregnancy coincide with these cardiovascular changes in the second and third trimester [8]. Whilst AVMs in HHT are suspected to form during infancy as vasculature develops and arteriovenous maturation occurs [2], there is no definitive data regarding the possibility of new lesions forming during pregnancy. Given the very low prevalence of spinal AVMs in this population, we suggest that patients with a clear pre‐pregnancy MRI of the spine are unlikely to require further imaging. If there is no prior imaging, based on the limited evidence, we advocate an unenhanced MRI in the late second or early third trimester. Our rationale for this timing is to optimise the likelihood of capturing a lesion, as unenhanced MRI may not detect small AVMs, which can enlarge as the pregnancy progresses, potentially increasing the yield if the scan is done later in pregnancy [1, 7].

Spinal AVMs in HHT are commonly located in the thoracic (68%) followed by the cervical spine (20%) [2]. The presence of spinal AVMs at any location along the spine can cause widespread abnormalities of venous drainage with resultant venous distension distant from the site of the actual AVM [4, 5]. Furthermore, loss of cerebrospinal fluid during dural puncture can place tension on the wall of distal spinal AVMs [9]. However, case reports of successful neuraxial anaesthesia in patients with distant spinal AVMs have been published, suggesting that the presence of a non‐lumbar spinal AVM is not an absolute contraindication [4, 5].

We suggest that neuraxial techniques be avoided in patients with HHT diagnosed with lumbar spinal AVMs with GA being recommended in cases requiring CD, and non‐neuraxial techniques for the management of analgesia in labour or operative vaginal deliveries. For AVM's at a distant location, the choice of anaesthetic technique would depend on the individual patients' risk–benefit analysis of GA versus neuraxial technique and the underlying anatomy of the lesion. If the risk of GA however is considered too high, an epidural could be considered, taking into consideration the known risk of accidental dural puncture of <1%. Our decision‐making algorithm for neuraxial anaesthesia options is represented in Fig. 1.

Figure 1.

Proposed decision‐making algorithm for neuraxial anaesthesia in cases of hereditary haemorrhagic telangiectasia during pregnancy. AVM: arterio‐venous malformation; MRI: magnetic resonance imaging; SA: spinal anaesthesia; DPE: dural puncture epidural; CSE: combined spinal‐epidural.