Biomechanical evaluation of lateral lumbar interbody fusion with secondary augmentation

OBJECTIVE Lateral lumbar interbody fusion (LLIF) has emerged as a popular method for lumbar fusion. In this study the authors aimed to quantify the biomechanical stability of an interbody implant inserted using the LLIF approach with and without various supplemental fixation methods, including an interspinous plate (IP). METHODS Seven human cadaveric L2-5 specimens were tested intact and in 6 instrumented conditions. The interbody implant was intended to be used with supplemental fixation. In this study, however, the interbody was also tested without supplemental fixation for a relative comparison of these conditions. The instrumented conditions were as follows: 1) interbody implant without supplemental fixation (LLIF construct); and interbody implant with supplemental fixation performed using 2) unilateral pedicle screws (UPS) and rod (LLIF + UPS construct); 3) bilateral pedicle screws (BPS) and rods (LLIF + BPS construct); 4) lateral screws and lateral plate (LP) (LLIF + LP construct); 5) interbody LP and IP (LLIF + LP + IP construct); and 6) IP (LLIF + IP construct). Nondestructive, nonconstraining torque (7.5 Nm maximum) induced flexion, extension, lateral bending, and axial rotation, whereas 3D specimen range of motion (ROM) was determined optoelectronically. RESULTS The LLIF construct reduced ROM by 67% in flexion, 52% in extension, 51% in lateral bending, and 44% in axial rotation relative to intact specimens (p < 0.001). Adding BPS to the LLIF construct caused ROM to decrease by 91% in flexion, 82% in extension and lateral bending, and 74% in axial rotation compared with intact specimens (p < 0.001), providing the greatest stability among the constructs. Adding UPS to the LLIF construct imparted approximately one-half the stability provided by LLIF + BPS constructs, demonstrating significantly smaller ROM than the LLIF construct in all directions (flexion, p = 0.037; extension, p < 0.001; lateral bending, p = 0.012) except axial rotation (p = 0.07). Compared with the LLIF construct, the LLIF + LP had a significant reduction in lateral bending (p = 0.012), a moderate reduction in axial rotation (p = 0.18), and almost no benefit to stability in flexion-extension (p = 0.86). The LLIF + LP + IP construct provided stability comparable to that of the LLIF + BPS. The LLIF + IP construct provided a significant decrease in ROM compared with that of the LLIF construct alone in flexion and extension (p = 0.002), but not in lateral bending (p = 0.80) and axial rotation (p = 0.24). No significant difference was seen in flexion, extension, or axial rotation between LLIF + BPS and LLIF + IP constructs. CONCLUSIONS The LLIF construct that was tested significantly decreased ROM in all directions of loading, which indicated a measure of inherent stability. The LP significantly improved the stability of the LLIF construct in lateral bending only. Adding an IP device to the LLIF construct significantly improves stability in sagittal plane rotation. The LLIF + LP + IP construct demonstrated stability comparable to that of the gold standard 360° fixation (LLIF + BPS).

Safety and Efficacy of Preoperative Embolization of Intracranial Hemangioblastomas

BACKGROUND

Intracranial hemangioblastomas are highly vascular tumors that account for 1% to 2% of all central nervous system tumors. Preoperative embolization has been proposed to limit the often significant intraoperative blood loss associated with resection and potentially make the tumor more soft/necrotic and thus more amenable to gross total resection. The safety and efficacy of preoperative embolization of intracranial hemangioblastomas, however, are not well characterized.

OBJECTIVE

To evaluate the safety and efficacy of preoperative endovascular embolization of intracranial hemangioblastomas using a variety of embolic agents.

METHODS

A retrospective review of all surgically resected intracranial hemangioblastomas treated with preoperative embolization between 1999 and 2014 at 2 high-volume centers was performed. Clinical and radiographic criteria, including von Hippel-Lindau status, magnetic resonance imaging tumor characteristics, embolization-related complications, degree of angiographic devascularization, intraoperative blood loss, ability to obtain gross total resection, transfusion requirements, and operative time, were analyzed.

RESULTS

A total of 54 patients underwent surgery, with 24 undergoing preoperative embolization followed by surgical resection, and 30 patients undergoing surgical resection alone. Embolization-related neurological complications were seen in 6 patients (25%), including 3 hemorrhages when polyvinyl alcohol particles (P = .04) were used and 3 infarctions when liquid embolic agents were used (P = .27). Permanent neurological deficits were seen in 15%.

CONCLUSION

Preoperative embolization of intracranial hemangioblastomas should be performed with caution, given the potential for neurological morbidity. Further studies are needed to help guide patient and embolic agent selection.

Melatonin Pathway and Atenolol-Related Glucose Dysregulation: Is There a Correlation?

Lower melatonin level, melatonin receptor gene variations, and atenolol treatment are associated with glucose dysregulation. We investigated whether atenolol‐related glucose and melatonin changes are correlated, and whether single nucleotide polymorphisms (SNPs) in melatonin candidate genes contribute to interindividual variation in glucose change. Hypertensive Caucasians (n = 232) from the Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR) study treated with atenolol for 9 weeks were studied. Urinary 6‐sulfatoxymelatonin (aMT6s) was measured pre‐ and posttreatment and normalized to urinary creatinine. Pharmacogenetic effects on glucose change of 160 SNPs in 16 melatonin candidate genes were assessed with multiple linear regression. Atenolol was associated with increased glucose (1.8 ± 10.1mg/dl, P = 0.02) and decreased aMT6s (–4.5 ± 10.1 ng/mg, P < 0.0001). However, the aMT6s change was not correlated with post‐atenolol glucose change. SNP rs11649514 in PRKCB was associated with glucose change (P = 1.0×10⁻⁴). PRKCB is involved in the melatonin‐insulin regulatory pathway, and may be important in mediating clinically meaningful atenolol‐related hyperglycemia.

CT/MRI Fusion for Vascular Mapping and Navigated Resection of a Paraspinal Tumor

BACKGROUND

Computed tomography/magnetic resonance imaging (CT/MRI) fusion is used increasingly in the surgical treatment of cranial pathology. The merging of these complementary modalities provides excellent visualization of the bony anatomy and clear delineation of the soft tissues, including neurovascular structures. To our knowledge, the application of CT/MRI fusion for the surgical management of spinal pathology has not been reported previously.

CASE DESCRIPTION

A 70-year-old woman presented with a paraspinal tumor that originated from the right psoas muscle and extended into the lumbar neuroforamina, with intricate involvement of the lumbar plexus and retroperitoneal vasculature. CT/MRI fusion was used to map out the vessels surrounding the tumor and for intraoperative navigation during resection of this invasive paraspinal tumor.

CONCLUSIONS

This case highlights both the feasibility and the advantages of applying CT/MRI fusion technology to the surgical treatment of spinal pathology.

Structure-mechanics relationships of collagen fibrils in the osteogenesis imperfecta mouse model

The collagen molecule, which is the building block of collagen fibrils, is a triple helix of two α1(I) chains and one α2(I) chain. However, in the severe mouse model of osteogenesis imperfecta (OIM), deletion of the COL1A2 gene results in the substitution of the α2(I) chain by one α1(I) chain. As this substitution severely impairs the structure and mechanics of collagen-rich tissues at the tissue and organ level, the main aim of this study was to investigate how the structure and mechanics are altered in OIM collagen fibrils. Comparing results from atomic force microscopy imaging and cantilever-based nanoindentation on collagen fibrils from OIM and wild-type (WT) animals, we found a 33% lower indentation modulus in OIM when air-dried (bound water present) and an almost fivefold higher indentation modulus in OIM collagen fibrils when fully hydrated (bound and unbound water present) in phosphate-buffered saline solution (PBS) compared with WT collagen fibrils. These mechanical changes were accompanied by an impaired swelling upon hydration within PBS. Our experimental and atomistic simulation results show how the structure and mechanics are altered at the individual collagen fibril level as a result of collagen gene mutation in OIM. We envisage that the combination of experimental and modelling approaches could allow mechanical phenotyping at the collagen fibril level of virtually any alteration of collagen structure or chemistry.

Autotransplantation of mesiodens for missing maxillary lateral incisor with cone-beam CT-fabricated model and orthodontics

AIM

Autotransplantation is a viable treatment option for a missing tooth when there is a suitable donor, especially in adolescents with remaining facial growth. This report presents the aesthetic restoration of a missing maxillary lateral incisor through orthodontic treatment and autotransplantation of a mesiodens using a CBCT-fabricated rapid-prototyping model.

SUMMARY

A 14-year-old male patient with a congenitally missing maxillary lateral incisor was referred from the Department of Orthodontics. The teeth were moved orthodontically to regain space for the missing lateral incisor and to close the space of the mesiodens after transplantation. A replica of the donor tooth was fabricated from a cone-beam computed tomography scan through a rapid-prototyping machine before autotransplantation surgery. The model was used to create a socket for the graft tooth, thereby shortening the extra-oral time and minimizing the damage to the root surface. After transplantation and orthodontic tooth movement, the mesiodens was finally restored with an aesthetic laminate restoration. Over 3 years, the aesthetics remained excellent, and the transplant functioned normally without any signs or symptoms of root resorption.

KEY LEARNING POINT

Missing anterior teeth may be replaced through a combination of orthodontics, autotransplantation with a rapid-prototyping model and prosthodontic restoration, in growing patients.

Diagnostic and surgical implications of ventral vertebrobasilar displacement by posterior fossa neurenteric cysts

OBJECTIVE

Neurenteric cysts (NECs) are uncommonly encountered lesions of the central nervous system with heterogeneous imaging characteristics. The object of this study was to review the preoperative imaging findings represented among a cohort of surgically treated posterior fossa NECs. These findings are considered in the context of surgical technique, and inform an understanding of aberrant neuroembryological development associated with NECs.

METHODS

A single-institution, multisurgeon series of 7 consecutive patients (5 female and 2 male patients, mean age 36 years, range 19 to 57 years) treated surgically for histopathologically confirmed posterior fossa NECs was retrospectively reviewed. Lesion imaging and anatomic characteristics were noted on preoperative magnetic resonance imaging (MRI). Imaging comparisons were made against an additional cohort of 266 consecutive surgically treated posterior fossa masses to validate unique anatomic findings.

RESULTS

T1 and T2 MRI signal characteristics were variable when compared across lesions. All NECs were found to be anteriorly located within the posterior fossa, but always situated between the brainstem pial surface and the vertebrobasilar system, causing ventral displacement of vertebrobasilar vessels.

CONCLUSIONS

Posterior fossa NECs display variable patterns of MRI signal and are commonly considered as part of a broad differential of cystic posterior fossa masses. We identified tumor insinuation between the ventral brainstem and vertebrobasilar system as a highly sensitive and specific radiographic sign for NECs. This finding was not observed among a large cohort of posterior fossa masses representative of other multiple pathologies.

Deferoxamine promotes osteoblastic differentiation in human periodontal ligament cells via the nuclear factor erythroid 2-related factor-mediated antioxidant signaling pathway

BACKGROUND AND OBJECTIVE

Recently it was reported that deferoxamine (DFO), an iron chelator, stimulates bone formation from MG63 and mesenchymal stem cells, but inhibits differentiation in rat calvarial cells; however, the effect of DFO on osteoblastic differentiation in human periodontal ligament cells (hPDLCs) has not been reported. The aim of this study was to investigate the effects and the possible underlying mechanism of DFO on osteoblastic differentiation of hPDLCs.

MATERIAL AND METHODS

The effect of DFO on osteoblast differentiation was determined by the staining intensity of calcium deposits with Alizarin red and by RT-PCR analysis of the expression of osteoblastic markers. Signal transduction pathways were analyzed by western blotting.

RESULTS

DFO increased osteogenic differentiation in a concentration-dependent manner by expression of the mRNA for differentiation markers and calcium nodule formation. Exposure of hPDLCs to DFO resulted in increases in the production of reactive oxygen species and in the levels of nuclear factor erythroid 2-related factor (Nrf2) protein in nuclear extractions, as well as a dose-dependent increase in the expression of Nrf2 target genes, including glutathione (GSH), glutathione S-transferase, γ-glutamylcysteine lygase, glutathione reductase and glutathione peroxidase. Pretreatment with Nrf2 small interfering RNA, GSH depletion by buthionine sulfoximine and diethyl maleate, and with antioxidants by N-acetylcysteine and vitamin E, blocked DFO-stimulated osteoblastic differentiation. Furthermore, pretreatment with GSH depletion and antioxidants blocked DFO-induced p38 MAPK, ERK, JNK and nuclear factor-kappaB pathways.

CONCLUSION

These data indicate, for the first time, that nontoxic DFO promotes osteoblastic differentiation of hPDLCs via modulation of the Nrf2-mediated antioxidant pathway.

Moxifloxacin modifies corneal fibroblast-to-myofibroblast differentiation

BACKGROUND AND PURPOSE

Fibroblast-to-myofibroblast differentiation is associated with scarring, an important issue in corneal surgery. Moxifloxacin (MOX), commonly applied to prevent post-operative infection, would benefit more if it modifies fibroblast-to-myofibroblast differentiation other than antimicrobial activity. Our purpose was to explore whether MOX has anti-fibrotic effect in human corneal fibroblasts (HCFs).

EXPERIMENTAL APPROACH

HCFs were incubated in MOX-containing medium concurrently with TGF-β1 (co-treatment), before (pretreatment) or after (post-treatment) adding TGF-β1. HCF contractility was evaluated with a type I collagen gel contraction assay. Expression of α-smooth muscle actin (α-SMA), Smad2, phospho-Smad2-Ser467, Smad4 and Smad7 was determined by immunoblotting. Formation of α-SMA-positive filaments and distribution of active Smad2 were observed under confocal microscopy. Expression of TGF-β receptor types I (TGFBR1) and II (TGFBR2) was assessed with flow cytometry.

KEY RESULTS

MOX did not affect gel contractility or α-SMA filament formation in HCFs without TGF-β1 stimulation. MOX did, however, retard HCF-containing gel contractility and α-SMA filament formation following TGF-β1 stimulation in the pretreatment and co-treatment groups but not in the post-treatment group. MOX blocked the expression of Smad2, phospho-Smad2-Ser467 and TGFBR1 under TGF-β1 incubation. Additionally, MOX enhanced Smad7 expression in TGF-β1-incubated HCFs, but did not interfere with TGF-β-triggered Smad2 nuclear translocation or Smad4 expression.

CONCLUSIONS AND IMPLICATIONS

MOX inhibited TGF-β-induced fibroblast-to-myofibroblast differentiation via blocking TGFBR1 and enhancing Smad7 expression. MOX should be used before or during surgery to achieve these effects. These results suggest a de novo mechanism by which MOX participates in corneal wound healing.

Strongyloides stercoralis infection in an intestinal transplant recipient

Strongyloides stercoralis is a helminth in tropical and subtropical areas. It may cause latent infection and progress to Strongyloides hyperinfection syndrome, which is associated with a high mortality rate. Transplant recipients under the treatment of immunosuppressant agents are at risk of severe S. stercoralis infection. According to related literature, most cases of S. stercoralis infection after solid organ transplantation are caused by reactivation of latent infections in the recipients, whereas only a few are acquired from the donors. We report on an intestinal transplant recipient who had S. stercoralis infection diagnosed by a larva of this parasite found in the stool from the ileostomy stoma 1 month after transplantation. The donor was considered the source of the infection because the donor was from an endemic area and had marked eosinophilia, and the recipient had no contact history or clinical manifestations related to the S. stercoralis infection before transplantation. The patient was treated with ivermectin and exhibited no evidence of infection after 7 months.

Microsurgical management of glomus spinal arteriovenous malformations: pial resection technique: Clinical article

OBJECT

Intramedullary, or glomus, spinal arteriovenous malformations (AVMs) are rare vascular lesions amenable to resection with or without adjuvant embolization. The authors retrospectively reviewed the senior author's (R.F.S.'s) surgical series of intramedullary spinal AVMs to evaluate clinical and radiographic outcomes.

METHODS

Detailed chart and radiographic reviews were performed for all patients with intramedullary spinal AVMs who underwent surgical treatment between 1994 and 2011. Presenting and follow-up neurological examination results were obtained and graded using the modified Rankin Scale (mRS) and McCormick Scale. Surgical technique, outcomes, complications, and long-term angiographic studies were reviewed.

RESULTS

During the study period, 20 patients (10 males and 10 females) underwent resection of glomus spinal AVMs. The mean age at presentation was 30 ± 17 years (range 7-62 years). The location of the AVMs was as follows: cervical spine (n = 10), thoracic spine (n = 9), and cervicothoracic junction (n = 1). The most common presenting signs and symptoms included paresis or paralysis (65%), paresthesias (40%), and myelopathy (40%). Perioperative embolization was performed in the majority (60%) of patients. Pial AVM resection was performed in 17 cases (85%). Angiographically verified AVM obliteration was achieved in 15 patients (75%). At a mean follow-up duration of 45.4 ± 52.4 months (range 2-176 months), 14 patients (70%) remained functionally independent (mRS and McCormick Scale scores ≤ 2). One perioperative complication occurred, yielding a surgical morbidity rate of 5%. Three symptomatic spinal cord tetherings occurred at a mean of 5.7 years after AVM resection. No neurological decline was observed after endovascular and surgical interventions. No deaths occurred. Long-term angiographic follow-up data were available for 9 patients (40%) at a mean of 67.6 ± 60.3 months (range 5-176 months) following AVM resection. Durable AVM obliteration was documented in 5 (83%) of 6 patients.

CONCLUSIONS

Intramedullary AVMs may be safely resected with satisfactory clinical and angiographic results. The pial resection technique, which provides subtotal AVM nidus resection, effectively devascularized these lesions, as confirmed on postoperative angiography, without violating the spinal cord parenchyma, thereby potentially reducing iatrogenic injury.

[Ultraviolet Mie lidar observations of aerosol extinction in a dust storm case over Macao]

Atmospheric aerosol over Macao was monitored by using a 355 nm Mie scattering lidar during the dust event on March 22nd, 2010. Vertical profiles of aerosol extinction coefficients were obtained and correlated with local PM10 concentration. The near-surface aerosol extinction coefficients have good agreement with PM10 concentration values. The aerosol extinction vertical profiles showed that there were distinct layers of dust aerosol concentration. The source and tracks of dust aerosol were analyzed by back-trajectory simulation. Observations showed that this lidar could run well even in dust storm episode, and it would help to further the study on aerosol properties over Macao.

Survival and functional outcome after surgical resection of intramedullary spinal cord metastases

OBJECTIVE

Intramedullary spinal cord metastasis (ISCM) is a rare manifestation of systemic cancer and data about the optimal management of these lesions are lacking. To clarify the role of surgery, we investigated survival and neurological outcomes after surgical resection of ISCMs.

METHODS

Between 2003 and 2010, we surgically treated 10 ISCMs in 9 patients. For each patient, we retrospectively collected the following data: demographic variables, history of prior cancer, site of primary cancer, extent of cancer on presentation, degree of resection, preoperative and postoperative spinal cord impairment (American Spinal Injury Association [ASIA] grade), and postoperative survival. We investigated the relationship between these variables, overall survival, and preservation of function.

RESULTS

Eight ISCMs were treated with gross total resection and two were treated with subtotal resection. Overall postoperative survival was 6.4 ± 9.4 months (mean ± standard deviation), with one patient still alive at last follow-up. Patients with a diagnosis of melanoma had higher mean survival than those with nonmelanoma histology (20.5 ± 13.4 vs. 2.4 ± 1.7 months, P < 0.01). Degree of resection, number of organ systems affected, ambulatory status, and ASIA grade pre operatively or postoperatively, were not significantly associated with survival. Of the nine patients, seven (78%) demonstrated no change in ASIA grade postoperatively, one (11%) improved, and one patient (11%) deteriorated. All patients who were ambulatory preoperatively remained ambulatory postoperatively and at last follow-up.

CONCLUSIONS

Although ISCM is associated with poor prognosis, survival appears to be greater in patients with melanoma. Surgical resection does not appear to significantly lengthen survival but may be indicated to preserve ambulatory status in symptomatic patients.

Cervical and lumbar spinal arthroplasty: clinical review

In contrast to cervical and lumbar fusion procedures, the principal aim of disk arthroplasty is to recapitulate the normal kinematics and biomechanics of the spinal segment affected. Following decompression of the neural elements, disk arthroplasty allows restoration of disk height and maintenance of spinal alignment. Based on clinical observations and biomechanical testing, the anticipated advantage of arthroplasty over standard arthrodesis techniques has been a proposed reduction in the development of symptomatic ALD. In this review of cervical and lumbar disk arthroplasty, we highlight the clinical results and experience with standard fusion techniques, incidence of ALD in the population of patients with surgical fusion, and indications for arthroplasty, as well as the biomechanical and clinical outcomes following arthroplasty. In addition, we introduce the devices currently available and provide a critical appraisal of the clinical evidence regarding arthroplasty procedures.

Surgical technique and outcomes in the treatment of spinal cord ependymomas, part 1: intramedullary ependymomas

BACKGROUND

Intramedullary spinal ependymomas are rare tumors.

OBJECTIVE

To provide a large retrospective review in the modern neuroimaging era from a tertiary center where aggressive surgical resection is favored.

METHODS

Charts of intramedullary spinal ependymomas treated between 1983 and 2006 were reviewed.

RESULTS

Sixty-seven cases were reviewed. The mean age was 45.6 years (range, 11-78 years) with a male-to-female ratio of 2:1. The most common location was the cervical spine, followed by the thoracic and lumbar spine. The average duration of symptoms was 33 months, with the most common symptom being pain and/or dysesthesias, followed by weakness, numbness, and urinary or sexual symptoms. Gross total resection was achieved in 55 patients and a subtotal resection was performed in 12 patients; 9 patients were treated with adjuvant radiation therapy. Mean follow-up was 32 months. The mean McCormick neurological grade at last follow-up was 2.0. The preoperative outcome correlated significantly with postoperative outcome (P < .001). A significant number of patients who initially worsened improved at their 3-month follow-up examination. Outcomes were significantly worse in patients undergoing subtotal resection with or without radiation therapy (P < .05). There were 3 recurrences. The overall complication rate was 34%. The primary complications were wound infections or cerebrospinal fluid leaks.

CONCLUSION

Spinal cord ependymomas are difficult lesions to treat. Aggressive surgical resection is associated with a high overall complication rate. However, when gross total resection can be achieved, overall outcomes are excellent and the recurrence rate is low.

Comparison of extraoral and transoral approaches to the craniocervical junction: morphometric and quantitative analysis

BACKGROUND

The transoral (TO) approach to the craniocervical junction provides similar access to the periclival and subaxial spine compared with the extraoral anterolateral prevascular (EAP) approach, but the additional exposure gained by the EAP approach has not been quantified. This study quantitatively compared the two surgical exposures.

METHODS

Ten silicon-injected fixed cadaver heads were used for the TO approach and another 5 heads (10 sides) were dissected for the EAP approach. For the TO approach, mouth opening was standardized to 5.5 cm using a Spetzler-Sonntag retractor, and the soft palate was split 1.5 cm to access the periclival area. A frameless stereotactic device was used to calculate the lengths, angles, and areas of surgical exposure for different anatomic targets.

RESULTS

The vertical working length on the dura progressively increased 61% (336 ± 26 mm to 539 ± 16 mm [mean ± standard deviation]; P < 0.001), and the vertical working angle increased 23% (98 ± 3 degrees to 121 ± 5 degrees; P < 0.0) using the TO versus the EAP approach. In the TO approach, the bilateral average horizontal working length on the C1 arch was less on the ipsilateral side than for the EAP approach (11 ± 1 mm vs. 17 ± 1 mm, 61%; P < 0.01). The mean periclival and subaxial exposures were 546 ± 72 mm(2) and 932 ± 70 mm(2) with the TO approach and 874 ± 75 mm(2) and 1644 ± 107 mm(2) with the EAP approach (mean increases 62% and 77%, respectively; both P < 0.001).

CONCLUSIONS

Both the TO and EAP approaches improved surgical exposure, but the EAP approach provides more significant and consistent gains to the anterolateral periclival and subaxial areas.

Through the choroidal fissure: a quantitative anatomic comparison of 2 incisions and trajectories (transsylvian transchoroidal and lateral transtemporal)

BACKGROUND

We compared the transsylvian transchoroidal (TSTC) approach with the lateral transtemporal (LTT) approach. Both approaches proceed through the choroidal fissure but through different incisions and along different trajectories.

METHODS

Four fixed, silicon-injected heads (8 sides) were used. Nine strategic anatomic points within the dissections were compared between the TSTC and LTT approaches in 7 other silicon-injected heads (14 sides). Neuronavigation was used to gather coordinates from selected points of both approaches to calculate surgical angles and distances to common targets.

RESULTS

The surgical angle of the TSTC approach for the inferior choroidal point was wider compared with the LTT approach (P < .05). The surgical angles for the P2a-P2p point were similar for both approaches. In the TSTC approach, the P2-P3 point angle was smaller than in the LTT approach (P < .05). The TSTC approach provided (except for the P2-P3 point) significantly shorter distances to all defined anatomic targets compared with the LTT approach. When the posterior cerebral artery was the target in the TSTC approach, the hippocampus was retracted 3 to 8 mm compared with 8 to 13 mm in the LTT approach.

CONCLUSION

We quantitatively described anatomic features of the TSTC approach and compared them with the LTT approach. For approaching the mesial temporal region, the TSTC approach offers an adequate surgical angle and shorter or similar distances proximal to P2-P3 and requires less temporal lobe and hippocampal retraction than the LTT approach. Such information can help surgeons select the optimal approach to the mesial temporal lobe and its surrounding structures. The TSTC approach should be considered for lesions located in the medial temporal region.

Gamma Knife surgery for hypothalamic hamartomas and epilepsy: patient selection and outcomes

Object

The authors present outcomes obtained in patients who underwent Gamma Knife surgery (GKS) at 1 institution as part of a multimodal treatment of refractory epilepsy caused by hypothalamic hamartomas (HHs).

Methods

Between 2003 and 2010, 19 patients with HH underwent GKS. Eight patients had follow-up for less than 1 year, and 1 patient was lost to follow-up. The 10 remaining patients (mean age 15.1 years, range 5.7–29.3 years) had a mean follow-up of 43 months (range 18–81 months) and are the focus of this report. Five patients had undergone a total of 6 prior surgeries: 1 transcallosal resection of the HH, 2 endoscopic transventricular resections of the HH, 2 temporal lobectomies, and 1 arachnoid cyst evacuation. In an institutional review board–approved study, postoperative complications and long-term outcome measures were monitored prospectively with the use of a proprietary database. Seven patients harbored Delalande Type II lesions; the remainder harbored Type III or IV lesions. Seizure frequency ranged from 1–2 monthly to as many as 100 gelastic seizures daily. The mean lesion volume was 695 mm3 (range 169–3000 mm3, median 265 mm3). The mean/median dose directed to the 50% isodose line was 18 Gy (range 16–20 Gy). The mean maximum point dose to the optic chiasm was 7.5 Gy (range 5–10 Gy). Three patients underwent additional resection 14.5, 21, and 32 months after GKS.

Results

Of the 10 patients included in this study, 6 are seizure free (2 after they underwent additional surgery), 1 has a 50%–90% reduction in seizure frequency, 2 have a 50% reduction in seizure frequency, and 1 has observed no change in seizure frequency. Overall quality of life, based on data obtained from follow-up telephone conversations and/or surveys, improved in 9 patients and was due to improvements in seizure control (9 patients), short-term memory loss (3 patients), and behavioral symptoms (5 patients); in 1 patient, quality of life remains minimally affected. Incidences of morbidity were all temporary and included poikilothermia (1 patient), increased depression (1 patient), weight gain/increased appetite (2 patients), and anxiety (1 patient) after GKS.

Conclusions

Of the approximately 150 patients at Barrow Neurological Institute who have undergone treatment for HH, the authors have reserved GKS for treatment of small HHs located distal from radiosensitive structures in patients with high cognitive function and a stable clinical picture, which allows time for the effects of radiosurgery to occur without further deterioration. The lack of significant morbidity and the clinical outcomes achieved in this study demonstrated a low risk of GKS for HH with results comparable to those of previous series.

The effect of obturator bulb height on speech in maxillectomy patients

The purpose of this study was to compare the speech function of low height bulb obturators with that of high height bulb obturators. Thirteen maxillectomy patients, who underwent post-operative prosthodontic rehabilitations, were included. Two obturators of the same design except for different bulb heights were fabricated for each maxillectomy patient. One of the two obturators had high bulb design and the other had low bulb design. After one of the obturators was used for a period of 3 weeks, the patient's speaking functions were evaluated by measuring nasalance scores, formant frequencies, and vowel working space areas. The same procedures were repeated with the second obturator following another 3-week period of usage. In addition, the effect of delivery sequence and anatomic conditions related to maxillectomy were analysed. The results demonstrated that the nasalance scores with the low bulb obturators were significantly higher than those with the high bulb obturators. There were no significant differences in formant frequencies based on the bulb height of the obturators. The vowel working spaces for the two obturators were similar in shape and there were no significant differences between the vowel working space areas created by the two obturators. The delivery sequence affected the results. However, there were no significant differences related to the other anatomical variables. Although low bulb obturators might function similarly with high bulb obturators in terms of the articulation of speech, they would exhibit a difficulty in controlling hypernasality in maxillectomy patients.

Treatment of Distal Posterior Cerebral Artery Aneurysms

OBJECTIVE

This is the largest contemporary series of distal posterior cerebral artery (PCA) aneurysms treated by use of endovascular coiling and stenting as well as surgical clipping, clip wrapping, and bypass techniques. We propose a new treatment paradigm.

METHODS

The location, size, type of aneurysm, clinical presentation, treatment, complications, and outcomes associated with 34 distal PCA aneurysms in 33 patients (15 females, 18 males; mean age, 44 years) were reviewed retrospectively.

RESULTS

The most common presenting symptom was headache in 19 (58%) followed by contralateral weakness or numbness in 6 (18%) and visual changes in 4 (12%). Eight aneurysms were giant. Of the remaining 26 aneurysms, 17 were fusiform/dissecting, 5 were saccular, and 4 were mycotic. Treatment was primarily endovascular in 22 patients, 12 of whom also had a concomitant surgical bypass procedure. Nine patients underwent microsurgical clipping, and 3 underwent combined treatment of clipping and coiling and/or stenting. There were no significant differences in outcomes between the groups (P = .078). The recurrence rate in patients undergoing coiling was 22% and 0% in patients undergoing clipping. Fourteen aneurysms (41%) involved treatment with an occipital artery-to-PCA bypass or an onlay graft. Compared with their preoperative status, these patients had significantly worse outcomes than those without a bypass (P = .013).

CONCLUSION

Bypass techniques for the treatment of distal PCA aneurysms are associated with a higher rate of complications than once thought. In our new treatment paradigm, bypass is a last resort and reserved for patients in whom balloon-test occlusion fails, who refuse parent-vessel sacrifice, and who cannot undergo primary stenting with coiling or clip wrapping.

Four-level anterior cervical discectomy and fusion with plate fixation: radiographic and clinical results

OBJECTIVE

Anterior cervical discectomy and fusion with plating is a common procedure performed for cervical spondylosis by spine surgeons. However, data on procedures involving 4 disc spaces are lacking. We report the outcomes of patients who underwent 4-level anterior cervical discectomy and fusion with plating at a single institution.

METHODS

Between 1997 and 2006, 34 patients (19 females, 15 males; mean age, 58 years; age range, 38-83 years) underwent 4-level anterior cervical discectomy and fusion with plating based on a surgical database search. Only patients undergoing surgery at 4 contiguous disc levels were included. Data were collected in a retrospective fashion. Patients' demographics, symptoms, neurologic findings, and radiographic findings at admission were recorded. Long-term clinical and radiographic outcomes at last follow-up were analyzed.

RESULTS

Twenty-nine patients (85%) underwent anterior cervical discectomy and fusion with plating at C3-C7. Sixteen patients presented with neurologic deficits, of which 14 (88%) improved. None worsened after surgery. Minor complications occurred in 26 patients, including transient dysphagia in 18 (53%) and hoarseness in 3 (9%). Radiographic outcomes were available in 27 patients (median follow-up, 15 months; range, 4-71 months). The overall fusion rate was 92.6%. Stable fibrous nonunions were present in 2 patients; the chance of nonunion was 1.9% per level and 7% per patient. Adjacent-level disease occurred in 2 patients.

CONCLUSION

In carefully selected patients, 4-level anterior cervical discectomy and fusion with plating can be associated with high rates of fusion. The technique is safe and effective for managing multilevel cervical spondylotic myelopathy and may obviate the need for circumferential procedures.

Occipitoatlantal dislocation

Occipitoatlantal dislocation (OAD) can be devastating. This injury may be fatal in many cases, but more survivors are reported because of improvements in diagnosis and treatment. This article describes the diagnosis and treatment of OAD. To diagnose and treat OAD appropriately, neurosurgeons must have a detailed understanding of the anatomy of the craniocervical junction. Various radiographic criteria are used to establish the diagnosis of OAD. A destabilizing injury such as OAD requires surgical fixation. Many surgical techniques are available for fixation of the craniocervical junction. Future studies will continue to refine the diagnostic criteria for OAD and to develop improved methods for craniocervical stabilization.

Preliminary personal experiences with the application of near-infrared indocyanine green videoangiography in extracranial vertebral artery surgery

INTRODUCTION

We evaluated the feasibility, usefulness, and limitations of near-infrared indocyanine green (ICG) videoangiography during procedures involving the extracranial vertebral artery (VA).

METHODS

Nine patients (2 women, 7 men; mean age, 55 years) were evaluated at 2 neurosurgical centers. Near-infrared ICG videoangiography was applied during transposition and rerouting of the first segment of VA (V1; n = 6) and during resection of neurinomas near the second (V2; n = 1) and third (V3; n = 2) segments of VA.

RESULTS

Early after ICG injection, V1 fluoresced homogenously. The fluorescence of V2 and V3 varied. Without extrinsic compression, these segments appeared as noncontiguous hot spots because the VA runs freely in a periosteal sheath surrounded by a venous plexus that attenuates the fluorescent light. Hot spots corresponded to areas where the artery neared the surface. With extrinsic compression, VA enhanced homogenously because it was pushed against the periosteal layer. During the late phase, the V1 signal was attenuated, whereas the venous plexus surrounding V2 and V3 enhanced homogeneously, thereby masking the VA itself. Near-infrared ICG videoangiography helped to confirm VA patency during transposition and rerouting but was not helpful during VA exposure because the periosteal sheath must already be exposed to detect the VA or its surrounding plexus. After exposure, videoangiography can help to determine the position of the VA within its periosteal sheath.

CONCLUSION

Videoangiography can be used to provide information about the patency of the VA and its location within the periosteal sheath to prevent injury during resection of tumor adherent to the periosteal sheath.