Hypothalamic hamartomas are rare, congenital malformations, associated with gelastic seizures, central precocious puberty, and developmental delay. Most lesions are medically refractory and require either surgical resection or radiosurgery. No large, multi-center studies have, to date, assessed complications and outcomes from surgical resection. Our study of the NIS data over a span of 10 years has demonstrated no inpatient mortalities, but has shown an approximately 20% overall inpatient complication rate, including, primarily, postoperative stroke. This analysis also reports useful new data regarding the average LOS and total hospital charges for this patient population.
The demographics of our patient population were similar in many respects to the previous single-center series. For instance, in our series approximately 53% of all patients treated were male. This male predominance in surgically treated hamartoma patients is noted throughout the literature, with the proportion of male patients ranging from 59.5 to 70% in varying series.[23
] The mean patient age within our study (27.7 years) was significantly higher than in past series. Other series have reported the mean patient age ranging from 8.7 years to 18.3 years of age.[2
] This may reflect the slightly older population that tends to be captured in the NIS database, as opposed to secondary data sources such as the Kids Inpatient Sample, which focuses more directly on inpatient pediatric diseases. More typically, younger patients perhaps being operated upon for the first time may have significantly different outcomes than the relatively older patients studied in this analysis. Future investigation and analyses focusing upon outcomes within the more common pediatric subset of patients with hypothalamic hamartomas may prove to elucidate additional clinically relevant predictors of postoperative inpatient outcomes. Furthermore, the mean LOS seems to be slightly higher in our dataset (7.39 days) relative to previously published reports, where the mean LOS has generally been reported to be approximately four days.[22
] It is unclear why the LOS was so much longer in our dataset. Given that our patient population was also significantly older than in other series, our population may reflect patients undergoing repeat attempts at surgical resection with a secondary prolonged hospital stay, although this hypothesis could not be testing due to limitations within our dataset.
The most common inpatient complication within our analysis was postoperative stroke, affecting approximately 16.7% of patients. This rate of postoperative stroke fell within the range of the previously reported rates, which ranged from 14 to 33%.[3
] Additionally, numerous past publications in the stroke literature validated our methodology of using ICD-9 diagnostic codes in an administrative database to capture the incidence of stroke as an inpatient complication. Our multivariate analysis demonstrated a modestly significant relationship between minority race / ethnicity and stroke (OR: 1.02, P
< 0.001). This relationship between race / ethnicity and postoperative stroke, among hypothalamic hamartoma patients, has not been reported previously. This finding could be related to the greater prevalence of stroke risk factors in minority populations, although a full elucidation of this hypothesis was not possible due to limitations of the dataset.[8
] Additionally, some relationships noted in our multivariate analysis, such as the relationship between insurance status and postoperative inpatient complications like stroke, have not been well-defined in the literature thus far, although we hope these findings provide an impetus for future mechanistic investigation. Future investigations of these associations through rigorous prospective trials would be helpful to further understand this clinical association.
In addition, an interesting trend consisting of a decreasing number of hypothalamic hamartoma resections per year has been noted throughout the 10 years of analyzed data. The number of attempted resections has decreased by nearly two-thirds (from 74 procedures over the years 1998 – 1999 to only 28 procedures over the years 2006 – 2007). Even as the exact reasoning for this rapid decline during the same time period is unclear, a number of articles reporting the relative safety and efficacy of radiosurgery for the treatment of hypothalamic hamartomas have been published, possibly swaying the referral patterns away from surgical resection and toward radiosurgery.[25
] Unfortunately, the NIS is not able to capture outpatient radiosurgery procedures, and thus exploration of this hypothesis was not able to be fulfilled at this time. Moreover, studies are investigating the potential rise of the radiosurgical treatment of hypothalamic hamartomas nationwide.
Interestingly, academic hospitals were associated with greater odds of inpatient complications, although they had significantly reduced total costs and length of stay. The exact mechanism underlying this relationship could not be fully elucidated from this dataset, but past studies in other surgical fields, exploring the relationship between hospital volume or teaching status and outcomes, may shed some additional light upon these findings.[4
] For instance, in the general surgery literature, Khuri et al
., demonstrated that patients undergoing simple colectomies and cholecystecomies at teaching hospitals had significantly higher complication rates than their counterparts treated at non-teaching hospitals.[19
] Postulated mechanism for higher complications in this subset of patients treated in academic settings included a greater turnover of patient care between staff and residents, as well as the often greater complexity of the health system at teaching institutions, leading to a higher recognition of complication at such institutions.[4
] Conversely, numerous reports in the general surgery literature focusing on pancreatic, hepatic, and esophageal cancer resections have demonstrated lower costs and shorter length of stay at academic centers, postulated to be, at least in part, due to the greater ancillary support at such centers expediting patient discharge and reducing the overall costs.[11
There are a number of limitations to this study. First, given the limitations of the dataset, we were unable to determine whether this relatively older patient population reflected patients undergoing repeat surgical resections. Additionally, due to limitations in coding, we were unable to fully elucidate the impact of varying surgical approaches, such as the transscallosal, orbitozygomatic, pterional, and transfrontal ventricular endoscopic approaches, upon patient complications and outcomes. Also, the use of and modifications to particular surgical techniques may have changed considerably over the past decade, making it difficult to draw definitive conclusions on the safety of particular surgical techniques. Furthermore, we have not been able to capture important pre- and intraoperative variables, such as the achievement of a gross total resection or full disconnection of the hamartoma, in addition to not being able to catalog important anatomical features of the tumor, such as tumor size and location, relative to important adjacent anatomical structures, such as the internal carotid artery, optic apparatus, oculomotor nerve, fornices, and mammillary bodies. Furthermore, our use of the NIS database was limited to only non-federal hospitals, precluding the analysis of patients treated at federal centers, such as the Veteran′s Affairs Hospitals. Given the relative rarity of surgical treatment for hypothalamic hamartomas, it may possibly be assumed that the outcomes would be improved at the hands of experienced surgeons or at high-volume centers. Unfortunately, the number of patients identified within the dataset were too small to fully assess these important research questions in the present analysis. Finally, this study was limited in its ability to follow patients after hospitalization to determine long-term seizure outcomes, as the NIS was limited to only inpatient outcome variables.
Nevertheless, we feel that this multi-institutional 10-year cohort analysis provides unique insights into a particular population of patients undergoing a surgical resection of hypothalamic hamartomas. We have found surgical resection to have relatively low inpatient mortality and have confirmed the occurrence of postoperative stroke as a significant complication risk through this nationwide series. Additionally, we have identified preoperative factors that increase patient risk for poor outcomes, which may help to risk-stratify patients for surgical resection or radiosurgery in the years ahead.