Delayed Cranioplasty: Outcomes Using Frozen Autologous Bone Flaps.

Reconstruction of skull defects following decompressive craniectomy is associated with a high rate of complications. Implantation of autologous cryopreserved bone has been associated with infection rates of up to 33%, resulting in considerable patient morbidity. Predisposing factors for infection and other complications are poorly understood. Patients undergoing cranioplasty between 1999 and 2009 were identified from a prospectively maintained database. Records and imaging were reviewed retrospectively. Demographics, the initial craniectomy and subsequent cranioplasty surgeries, complications, and outcomes were recorded. A total of 187 patients underwent delayed cranioplasty using autologous bone flaps cryopreserved at -30°C following decompressive craniectomy. Indications for craniectomy were trauma (77.0%), stroke (16.0%), subarachnoid hemorrhage (2.67%), tumor (2.14%), and infection (2.14%). There were 64 complications overall (34.2%), the most common being infection (11.2%) and bone resorption (5.35%). After multivariate analysis, intraoperative cerebrospinal fluid (CSF) leak was significantly associated with infection, whereas longer duration of surgery and unilateral site were associated with resorption. Cranioplasty using frozen autologous bone is associated with a high rate of infective complications. Intraoperative CSF leak is a potentially modifiable risk factor. Meticulous dissection during cranioplasty surgery to minimize the chance of breaching the dural or pseudodural plane may reduce the chance of bone flap.

Clinical, radiological, and microbiological profile of patients with autogenous cranioplasty infections.

OBJECTIVE: Bone flap infections after autogenous cranioplasty can present a diagnostic and management challenge. Little is known about the clinical, radiological, and microbiological profile of these patients. METHODS: Patients who developed bone flap infective complications requiring explantation after autogenous cranioplasties between 1999 and 2009 were identified. Their prospectively collected demographic details, clinical presentation, radiological features, surgical intervention, microbiological profile, and treatment outcomes were retrospectively reviewed. RESULTS: During the study period, 179 cranioplasties were performed with frozen autogenous skull flaps. Seventeen patients (10%, median age 25 years) experienced deep infections that necessitated flap removal and antimicrobial treatment. Although fever, swelling of the scalp, and local inflammation were present in majority of patients (76.5%), inflammatory markers were abnormal only in 33%. Computed tomography imaging features included extra-axial collection (76.5%), subgaleal collection or galeal swelling (70.6%), cerebritis (37.5%), and osteomyelitis (23.5%). Positive bacterial cultures were obtained from all (100%) explanted bone flaps, including gram-positive (82.3 %) and -negative (17.7%) organisms. A significant proportion (29.4%) of patients presented with complications late during follow-up (>6 weeks); 60% of these were attributable to Propionibacterium acnes infection. CONCLUSIONS: Clinical assessment is critical to the diagnosis of bone-flap infection. A high index of suspicion is necessary because late presentations are possible. Empirical antimicrobial treatment should include gram-negative coverage.

Microbial contamination assessment of cryostored autogenous cranial bone flaps: should bone biopsies or swabs be performed?

BACKGROUND: Autogenous cranioplasty infection requiring bone flap removal is under-recognised as a major complication causing significant morbidity. Microbial contamination of stored bone flaps may be a significant contributing factor. Current infection control practices and storage procedures vary. It is not known whether 'superficial' swabs or bone cultures provide a more accurate assessment. METHOD: Twenty-five skull flaps that were cryo-stored for more than 6 months were studied. Two swab samples (superficial and deep) and a bone biopsy sample were taken from each skull flap sample and cultured. Half blood agar and half chocolate agar plates were inoculated with the swabs for anaerobic and aerobic cultures respectively. The bone biopsy samples were cultured in brain-heart broth and subcultured similar to the swabs for 5 days. RESULTS: Incidence of microbial contamination was 20 % in the bone flaps studied. One swab culture and five bone biopsy cultures were positive for bacterial growth, all of which contained Propionibacterium acnes (p = 0.014). Positive cultures were from bone flaps stored less than 18 months, whereas no growth was obtained from bone flaps that were stored longer (p = 0.014). CONCLUSIONS: Bone biopsy culture is a more sensitive technique of assessing microbial contamination of cryo-stored autogenous bone flaps than swab cultures. The clinical implications of in vitro demonstration of microbial contamination require further study.

Autogenous skull flaps stored frozen for more than 6 months: do they remain viable?

Autogenous cranioplasties with cryopreserved skull flaps are associated with disproportionately high infection and bone resorption rates. Bone flap non-viability may be a contributing factor. Viable osteoblasts have been cultured recently from cryopreserved long bones. Cryopreserved skull bone may also remain viable based on histological observations. However, cell culture studies have not been performed on skull bone to assess viability. Bone explant cell cultures were performed on 27 skull flaps stored at -30 °C for more than 6 months. Biopsies were taken from the flaps, washed in phosphate buffer saline and cultured in Dulbecco's Modified Eagle's medium at 37 °C in 5% carbon dioxide for 3 weeks. Fresh skull bone samples served as controls. While control samples showed growth of osteoblasts, no osteoblasts were cultured from the study specimens at 3 weeks. In conclusion, skull flaps cryopreserved at -30 °C for more than 6 months are non-viable. Further research characterizing impact of different storage conditions on skull flap viability is warranted.

Bone flap storage following craniectomy: a survey of practices in major Australian neurosurgical centres.

INTRODUCTION: The resurgence of decompressive craniectomy surgeries for management of intracranial hypertension has led to a parallel increase in cranioplasty procedures for subsequent reconstruction of the resultant extensive skull defects. Most commonly, cranioplasties are performed using the patients' own cryopreserved skull flaps. Currently, there are no standardized guidelines for freeze-storage of bone flaps either nationally or internationally. In this initial study, the authors surveyed major neurosurgical centres throughout Australia to document current clinical practices. METHODOLOGY: Twenty-five neurosurgical centres affiliated with major public, teaching hospitals in all Australian states were included in the current survey study. A standardized survey guide incorporating standardized questions was used for data collection either by phone interviews and/or electronic (email) communication. Details regarding bone flap preparation following craniectomy, temperature and duration of freeze-storage, infection control/micro-contamination detection protocols, pre-implantation procedures were specifically recorded. RESULTS: Cranioplasty using cyropreserved autogenous bone flaps remains the most common (96%) mode of skull defect reconstruction in major neurosurgical centres throughout Australia. Following the initial craniotomy, the harvested skull flaps were most frequently (88%) double- or triple-bagged under dry, sterile conditions. In 16% of hospitals, skull flaps were irrigated either with antibiotic mixed-saline or Betadine prior to cryopreservation. Skull biopsies or swabs were obtained from the skull flaps for micro-contamination studies in accordance with departmental protocol in 68% of hospitals surveyed. Subsequently, the bone flaps were cryopreserved at wide ranging temperatures between -18°C to -83°C, for variable time intervals (6 months to 'until patient deceased'). Twelve neurosurgical centres (48%) elected for bone flap storage to be undertaken at the local bone bank. In the remainder (52%) of the hospitals, bone flaps were cryopreserved in locally maintained freezers. Prior to re-implantation of the skull flaps at subsequent cranioplasty surgeries, six (24%) of the neurosurgical centres had specific thawing procedures involving immersion of the frozen bone flaps in Ringer's solution and/or Betadine. Further pre-implantation bacteriological cultures from bone biopsies or swabs were obtained only in three (12%) hospitals. CONCLUSIONS: This study has documented highly varied skull flap cryopreservation and storage practices in neurosurgical centres throughout Australia. These differences may contribute to relatively high complication rates of infection and bone resorption reported in the literature. The results of the current study argue for the further need of high quality clinical and basic science research, which aims to characterize the effect of current skull flap management practices and freeze-storage conditions on the biological and biomechanical properties of skull bone.

Brainstem compression from a trigeminal schwannoma presenting with pathological crying.

Patients with pathological laughter and crying have episodes of uncontrollable laughter, crying or both. Pathological laughter is a well-described entity secondary to various conditions such as multiple sclerosis, pseudo-bulbar palsy, cerebello-pontine angle tumours, clival chordomas and brainstem gliomas. Pathological crying is rare and there have been no previous reports of brainstem compression causing this entity. We report a patient who presented with pathological crying caused by a trigeminal schwannoma with a tumor-associated cyst indenting the pons. This case report confirms the involvement of the cortico-ponto-cerebellar pathways in the pathogenesis of pathological crying.