Patient functional outcomes after cerebrovascular neurosurgery: a comparison of function and quality of life after conservative or surgical management of unruptured intracranial aneurysm and brain arteriovenous malformation

The consequences of a haemorrhage from an intracranial aneurysm (IA) or brain arteriovenous malformation (AVM) rupture can cause a significant impact on a patient's quality of life (QOL). In addition, the knowledge of the presence of an unruptured IA (uIA) or unruptured brain AVM can also have a negative impact on such a person's QOL. The primary aim of surgery for uIA and unruptured brain AVM (AVM) is to prevent their subsequent rupture. However, studies have questioned the effectiveness of surgery for the management of uIA and unruptured AVM.(Wiebers, Whisnant et al. 2003, Mohr, Parides et al. 2014) The instrument employed in these studies for measuring success or failure of treatment is a disability scale that considers the level of function of everyday living tasks, the modified Rankin Scale (mRS).(Rankin 1957, Van Swieten 1988, Koudstaal et al. 1988) Although everyday living tasks may include driving, whether or not a patient can return to driving has hitherto been poorly defined and unstudied. This thesis examined the effectiveness of surgical management of uIA and AVM by measuring performance of self-care tasks, patients' perceived quality of life, cognitive abilities related to driving and restriction of driving due to the risk of seizures after surgery. There are two categories that may impact upon these patients returning to driving, constant persistent disabilities and the episodic events of seizures. Section 1 of this thesis outlines investigations into the functional outcomes of surgery for uIA and AVM. Patients referred to Macquarie University (MQ) for management of uIA and AVM were assessed pre-operatively and at each follow up for 12 months using the modified Barthel Index (mBI), the modified Rankin Scale (mRS), DriveSafe DriveAware, and the Short Form 36 (SF36) Quality of Life (QOL) questionnaire. The SF36 subscales of Physical Component Score (PCS) and Mental Component Score (MCS) were used in analyses. There was no overall significant decline in function or QOL 12 months after surgery for uIA or AVM for the cohort.(O'Donnell J. 2013) There was no significant difference in the DriveSafe scores between the surgical group and the conservative group at 12months (mean 112 SD10, mean 110 SD8.7 respectively; p=0.23 mean difference 2.62 95%CI -1.7 to 6.9).There was no significant difference in function or QOL after one year between conservatively managed and surgically managed uIA patients (DriveSafe p=0.23, PCS p=0.51, MCS p=0.54). Surgically managed uIA patients experienced a temporary decline in QOL immediately after surgery, however QOL returned to pre-operative levels one year after surgery (52 SD 8.1, 46 SD 6.8 and 52 SD 7.1 respectively)(p<0.01) (paper submitted for publication). The AVM study showed surgical resection of AVM does not affect function or QOL for low-grade AVM. There was no significant difference in decline in function in conservatively managed or surgically managed AVM one year after initial presentation or surgery, respectively (p=0.43). Functional outcomes after surgery were better for lower SpetzlerPonce (SP) grade than higher grade AVMs (SP C versus B [p=0.04, mean difference -14.6, 95%CI -28.6 to -0.6] and the SP C versus A [p=0.04, mean difference -12.4, 95%CI -24.3 to -0.4]). Function and QOL were not compromised by conservative management of high grade AVM, while surgical repair of low grade AVM may improve QOL (PCS p<0.01; MCS p=0.02) without affecting function (paper submitted for publication) The risk of seizure after discharge from hospital for surgical repair of a uIA or an AVM was examined in section 2 to determine if seizure risks would inhibit participation in work and driving.(Lai, O'Donnell et al. 2013) A neurosurgical retrospective cohort of uIA and AVM patients was analysed to examine the incidence of post-operative seizures. The risk of seizures after discharge from hospital following surgery for uIA, when there is no pre-existing risk of seizures and no complications as a result of surgery, is low (<0.1% and 1.1% at 12 months and 7 years respectively).(O'Donnell, Morgan et al. 2016) For AVM, the risk of seizures increases with the maximum diameter of the AVM and a patient history of more than two preoperative seizures.(O'Donnell, Morgan et al. 2017) The 7-year risk of developing postoperative seizures ranged from 11% for patients with AVM ≤ 4 cm and with 0 to 2 preoperative seizures, to 59% for patients with AVM >4 cm and with >2 preoperative seizures.(O'Donnell, Morgan et al. 2017)The risk of seizure after discharge from hospital for surgical repair of a uIA or an AVM was examined in section 2 to determine if seizure risks would inhibit participation in work and driving.(Lai, O'Donnell et al. 2013) A neurosurgical retrospective cohort of uIA and AVM patients was analysed to examine the incidence of post-operative seizures. The risk of seizures after discharge from hospital following surgery for uIA, when there is no pre-existing risk of seizures and no complications as a result of surgery, is low (<0.1% and 1.1% at 12 months and 7 years respectively).(O'Donnell, Morgan et al. 2016) For AVM, the risk of seizures increases with the maximum diameter of the AVM and a patient history of more than two preoperative seizures.(O'Donnell, Morgan et al. 2017) The 7-year risk of developing postoperative seizures ranged from 11% for patients with AVM ≤ 4 cm and with 0 to 2 preoperative seizures, to 59% for patients with AVM >4 cm and with >2 preoperative seizures.(O'Donnell, Morgan et al. 2017) The third section of this thesis investigated the outcomes of cerebrovascular surgery by examining QOL compared with disability ratings and function. The QOL of conservatively managed unruptured AVM was compared with surgically managed unruptured AVM in 2 separate cohorts.(O'Donnell and Morgan 2015) Results on 79 Scottish and 41 MQ patients found a significant relationship between mRS and QOL in the combined cohort (p < 0·01) but did not find significant differences in the QOL scores between conservatively and surgically managed uAVM (paper submitted for publication). The thesis concludes with the importance of using a broad range of instruments to assess patients outcomes related to disabilities and QOL following surgery for uIA and AVM. The final paper submitted for publication found poor correlation between the MCS subscale of the SF36 QOL scales and the instrument of disability commonly used to judge outcomes (mRS). This study demonstrated that both the results of DriveSafe instrument and the PCS subscale of SF36 correlated with mRS. However, for a more comprehensive picture of a patient's recovery from surgery, QOL and Drivesafe scores should be added to the mRS. Based on our results, we concluded that surgery can be generally effective without compromise with respect to function or QOL for the management of uIA or AVM. Functional cognitive screening is recommended prior to surgery for AVM. Consideration should be given for psychological support when individual SF36 results indicate low pre-operative MCS scores. Indicators for the restriction of driving after surgery for uIA and AVM have been identified.