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Skull Base Reconstruction Using Free Flaps Following Extended Tumor Ablation: A Retrospective Study of 45 Cases

METHODS: The Global Burden of Disease methodology was used to estimate prevalence and morbidity of orofacial clefting in 195 countries from 1990 to 2017. Disability-adjusted life years (DALYs) and prevalence were compared over time, geographically, and against the sociodemographic index (SDI) and size of the national surgical workforce. Linear and logarithmic regressions were performed. Our international authorship hypothesizes on multiple factors contributing to this change based on their region’s perspective.


METHODS:
The Global Burden of Disease methodology was used to estimate prevalence and morbidity of orofacial clefting in 195 countries from 1990 to 2017. Disability-adjusted life years (DALYs) and prevalence were compared over time, geographically, and against the sociodemographic index (SDI) and size of the national surgical workforce. Linear and logarithmic regressions were performed. Our international authorship hypothesizes on multiple factors contributing to this change based on their region's perspective.

RESULTS:
From 1990 to 2017, the number of clefts worldwide decreased by 4.9% to 10.8 million and the burden of this disease significantly decreased by 70.2% to 652,084 DALYs. In 2017, low-and middle-income countries experienced 83.5% of the DALY burden. The largest decreases in DALY were seen in East Asia and the Pacific (83.6% decrease) and Sub-Saharan Africa (73.1% decrease), whereas North America (14.2% decrease) and high-income countries (20.5% decrease) remained neutral. Prevalence was weakly positively associated with increasing SDI (r = 0.43; r 2 = 0.18), whereas DALYs were negatively associated with SDI (r = −0.79; r 2 = 0.48). There was a logarithmic association between the estimated surgical workforce and the disease burden, with significantly fewer DALYs in countries that had a surgical workforce of >6 providers per 100,000 population.

CONCLUSION:
The burden of orofacial clefts has decreased significantly despite steady prevalence over the past 28 years. Most of the burden of orofacial clefting is carried by low-and middle-income countries, and the prevalence of orofacial clefting is not strongly correlated with the sociodemographic index. Strengthening the surgical workforce may aid in decreasing the life-long disease burden of orofacial clefting for any given country.

Co-Authors: Takuya Iida, MD, PhD; Mutsumi Okazaki, MD, PhD
Affiliation: The University of Tokyo, Tokyo, Japan BACKGROUND: Oncologic resections at the skull base often result in extended defects and exposure of the brain, dura, and adjacent structures, and sometimes patients suffer from fatal postoperative complications like meningitis and cerebrospinal fluid leak. 1 The primary goals of skull base reconstruction involve separation of central nervous system from external or mucosal contamination, obliterating dead space, and restoring acceptable appearance and function when possible. Although small defects can often be successfully closed using local flaps or distant pedicled flaps, surgical resection frequently results in the creation of complex, large, and 3-dimensional defects, which can be reconstructed only through the use of microvascular tissue transfer. 2,3 METHODS: A retrospective study was conducted of patients diagnosed with tumors infiltrating the skull base, who underwent extended tumor resection and primary microvascular free flap reconstruction between 2007 and 2017 at the University of Tokyo, Japan. The parameters investigated include demographics, tumor characteristics, preoperative therapies, reconstructive procedures, and above all, postoperative complications.

RESULTS:
Forty-three patients underwent a total of 45 skull base free flap reconstruction during the study period. Twenty-eight males and 15 females were included in the study. Two patients developed a tumor recurrence and were treated with surgical skull base resection and a second microvascular reconstruction. The mean age was 55.8 years (range, PSTM 2019 Abstract Supplement Craniofacial Abstracts 1-80 years) at operation. 4 Tumors were resected via an open extracranial approach and all operation included resection of a portion of skull base and exposure of the intracranial compartments to skin or upper aerodigestive tract. Reconstruction was undertaken using mainly the rectus abdominis musculocutaneous flap (69%), followed by the anterolateral thigh flap (22%). Latissimus dorsi musculocutaneous flap and superficial circumflex iliac perforator flap were used in 2 cases each. 5 . There were no flap losses, no reoperations due to anastomoses-related complications, and no perioperative death.

CONCLUSION:
In our series, free flap transfer is versatile for skull base reconstruction and safely utilized even in a 1-year-old infant or the elderly. Multiple reconstructions using free flaps were successfully conducted in 2 cases. With consideration for tumor characteristics, defects following tumor ablation, donor-site morbidity, and patient's background, we choose optimal flap for each patient and pursue more reliable and esthetic reconstructions and less donor-site morbidities.