Abdominal complications following kyphosis correction in ankylosing spondylitis.

Spinal deformity surgery is associated with high rates of morbidity and a wide range of complications. The most significant abdominal complications following kyphosis correction, while uncommon, can certainly pose significant infectious and hemodynamic risks to the patient. Abdominal compartment syndrome is the most severe of the sequelae. It is the end result of elevated abdominal compartment pressure with physiological compromise and end organ system dysfunction. Although most commonly associated with trauma, abdominal compartment syndrome has also been witnessed following massive fluid shifts, which can occur during adult spinal deformity surgery. In this manuscript, we report on 2 patients with ankylosing spondylitis who developed significant abdominal pathology requiring exploratory laparotomy following kyphosis correction. In addition to describing the details of each case, we propose explanations of the relevant pathophysiology and review diagnostic and treatment strategies for such events. The key to effectively treating such a debilitating complication is to recognize it quickly and intervene rapidly and aggressively.

Posterior vertebral column subtraction osteotomy: a novel surgical approach for the treatment of multiple recurrences of tethered cord syndrome.

Recurrent tethered cord syndrome (TCS) has been reported to develop in 5-50% of patients following initial spinal cord detethering operations. Surgery for multiple recurrences of TCS can be difficult and is associated with significant complications. Using a cadaveric tethered spinal cord model, Grande and colleagues demonstrated that shortening of the vertebral column by performing a 15-25-mm thoracolumbar osteotomy significantly reduced spinal cord, lumbosacral nerve root, and terminal filum tension. Based on this cadaveric study, spinal column shortening by a thoracolumbar subtraction osteotomy may be a viable alternative treatment to traditional surgical detethering for multiple recurrences of TCS. In this article, the authors describe the use of posterior vertebral column subtraction osteotomy (PVCSO) for the treatment of 2 patients with multiple recurrences of TCS. Vertebral column resection osteotomy has been widely used in the surgical correction of fixed spinal deformity. The PVCSO is a novel surgical treatment for multiple recurrences of TCS. In such cases, PVCSO may allow surgeons to avoid neural injury by obviating the need for dissection through previously operated sites and may reduce complications related to CSF leakage. The novel use of PVCSO for recurrent TCS is discussed in this report, including surgical considerations and techniques in performing PVCSO.

Dimensions of the Subaxial Lateral Mass: A Systematic Review of Anatomic (Morphometric) Measurement Studies.

STUDY DESIGN: This was a systematic review. OBJECTIVE: To review and synthesize information on subaxial lateral mass dimensions in order to determine the ideal starting point, trajectory, and size of a lateral mass screw. SUMMARY OF BACKGROUND DATA: The use of lateral mass instrumentation for posterior cervical decompression and fusion has become routine as these constructs have increased rigidity and fusion rates. METHODS: A systematic search of Medline and EMBASE was conducted. Studies that provided subaxial cervical lateral mass measurements, distance to the facet, vertebral artery and neuroforamen and facet angle made either directly (eg, cadaver specimen) or from patient imaging were considered for inclusion. Pooled estimates of mean dimensions were reported with corresponding 95% confidence intervals. Stratified analysis based on level, sex, imaging plane, source (cadaver or imaging), and measurement method was done. RESULTS: Of the 194 citations identified, 12 cadaver and 10 imaging studies were included. Pooled estimates for C3-C6 were generally consistent for lateral mass height (12.1 mm), width (12.0 mm), depth (10.8 mm), distance to the transverse foramen (11.8 mm), and distance to the nerve. C7 dimensions were most variable. Small sex-based differences in dimensions were noted for height (1.2 mm), width (1.3 mm), depth (0.43 mm), transverse foramen distance (0.9 mm), and nerve distance (0.3-0.8 mm). No firm conclusions regarding differences between measurements made on cadavers and those based on patient computed tomographic images are possible; findings were not consistent across dimensions. The overall strength of evidence is considered very low for all findings. CONCLUSIONS: Although estimates of height, width, and depth were generally consistent for C3-C6, C7 dimensions were variable. Small sex differences in dimensions may suggest that surgeons should use a slightly smaller screw in female patients. Firm conclusions regarding facet angulation, source of measurement, and method of measurement were not possible.

Maximizing the potential of minimally invasive spine surgery in complex spinal disorders.

Minimally invasive surgery (MIS) in the spine was primarily developed to reduce approach-related morbidity and to improve clinical outcomes compared with those following conventional open spine surgery. Over the past several years, minimally invasive spinal procedures have gained recognition and their utilization has increased. In particular, MIS is now routinely used in the treatment of degenerative spine disorders and has been shown to be as effective as conventional open spine surgeries. Although the procedures are not yet widely recognized in the context of complex spine surgery, the true potential in minimizing approach-related morbidity is far greater in the treatment of complex spinal diseases such as spinal trauma, spinal deformities, and spinal oncology. Conventional open spine surgeries for complex spinal disorders are often associated with significant soft tissue disruption, blood loss, prolonged recovery time, and postsurgical pain. In this article the authors review numerous cases of complex spine disorders managed with MIS techniques and discuss the current and future implications of these approaches for complex spinal pathologies.

A novel approach to sagittal balance restoration following iatrogenic sacral fracture and resulting sacral kyphotic deformity. Technical note.

The authors describe the use of sacral pedicle subtraction osteotomy (PSO) with multiple sacral alar osteotomies for the correction of sacral kyphosis and pelvic incidence and for achieving sagittal balance correction in cases of fixed sagittal deformity after a sacral fracture. In this paper, the authors report on a novel technique using a series of sacral osteotomies and a sacral PSO to correct a fixed sagittal deformity in a patient with a sacral fracture that had healed in a kyphotic position. The patient sustained this fracture after a previous surgery for multilevel instrumented fusion. Preoperative and postoperative radiographic studies are reviewed and the clinical course and outcome are presented. Experts agree that the pelvic incidence is a fixed parameter that dictates the morphological characteristics of the pelvis and affects spinopelvic orientation and sagittal spinal alignment. An increased pelvic incidence is associated with a higher degree of spondylolisthesis in the lumbosacral junction, and increased shear forces across this junction. The authors demonstrate that the pelvic incidence can be altered and corrected with a series of sacral osteotomies to improve sacral kyphosis, compensatory lumbar hyperlordosis, and sagittal balance.

Anterior lumbar interbody fusion in comparison with transforaminal lumbar interbody fusion: implications for the restoration of foraminal height, local disc angle, lumbar lordosis, and sagittal balance.

OBJECT: A primary consideration of all spinal fusion procedures is restoration of normal anatomy, including disc height, lumbar lordosis, foraminal decompression, and sagittal balance. To the authors' knowledge, there has been no direct comparison of anterior lumbar interbody fusion (ALIF) with transforaminal lumbar interbody fusion (TLIF) concerning their capacity to alter those parameters. The authors conducted a retrospective radiographic analysis directly comparing ALIF with TLIF in their capacity to alter foraminal height, local disc angle, and lumbar lordosis. METHODS: The medical records and radiographs of 32 patients undergoing ALIF and 25 patients undergoing TLIF from between 2000 and 2004 were retrospectively reviewed. Clinical data and radiographic measurements, including preoperative and postoperative foraminal height, local disc angle, and lumbar lordosis, were obtained. Statistical analyses included mean values, 95% confidence intervals, and intraobserver/interobserver reliability for the measurements that were performed. RESULTS: Our results indicate that ALIF is superior to TLIF in its capacity to restore foraminal height, local disc angle, and lumbar lordosis. The ALIF procedure increased foraminal height by 18.5%, whereas TLIF decreased it by 0.4%. In addition, ALIF increased the local disc angle by 8.3 degrees and lumbar lordosis by 6.2 degrees, whereas TLIF decreased the local disc angle by 0.1 degree and lumbar lordosis by 2.1 degrees. CONCLUSIONS: The ALIF procedure is superior to TLIF in its capacity to restore foraminal height, local disc angle, and lumbar lordosis. The improved radiographic outcomes may be an indication of improved sagittal balance correction, which may lead to better long-term outcomes as shown by other studies. Our data, however, demonstrated no difference in clinical outcome between the two groups at the 2-year follow-up.

A granulomatous reaction to Avitene mimicking recurrence of a medulloblastoma. Case report.

Microfibrillar collagen hemostat (MCH), also known by its trade name Avitene, is commonly used to control hemorrhage during neurosurgery. Among the documented complications associated with this agent, a granulomatous foreign body reaction is rare, having been described in the central nervous system in only one previous clinical report. In the present study, the authors report the case of a 3-year-old boy who presented with a lesion which appeared to be the recurrence of a tumor 2 months after he had undergone gross-total resection for a medulloblastoma. The patient underwent resection of the presumed recurrent tumor, but histopathological analysis of the specimen revealed a granulomatous foreign body reaction to MCH and no tumor recurrence. In addition to describing the case, the authors review the surgical literature on foreign body reactions to MCH.

Acquired Chiari malformation Type I associated with a supratentorial arteriovenous malformation. Case report and review of the literature.

Chiari malformation Type I (CM-I), a condition defined by caudal descent of the cerebellar tonsils through the foramen magnum, is generally considered a congenital lesion. Several authors, however, have described an acquired form that appears identical to the congenital lesion on neuroimages. The most commonly reported cause of an acquired CM-I is cerebrospinal fluid diversion through a lumboperitoneal shunt. In this paper, the authors report the case of a patient in whom an acquired CM-I developed in association with a supratentorial arteriovenous malformation (AVM) of the brain. Development of the acquired CM was documented on serial magnetic resonance images. Moreover, the CM was seen to originate and worsen in concert with the clinicoradiological progression of the AVM. The underlying mechanism responsible for the acquired CM in this case is thought to be a high-flow venopathy of the transverse and sigmoid sinuses causing occlusion on the right and redirection of venous outflow into posterior fossa veins, with consequent venous congestion and swelling of the posterior fossa structures.

Spinal Implant Density and Postoperative Lumbar Lordosis as Predictors for the Development of Proximal Junctional Kyphosis in Adult Spinal Deformity.

OBJECTIVE: To evaluate spinal implant density and proximal junctional kyphosis (PJK) in adult spinal deformity (ASD). METHODS: Consecutive patients with ASD receiving ≥5 level fusions were retrospectively analyzed between 2007 and 2010. INCLUSION CRITERIA: ASD, elective fusions, minimum 2-year follow-up. EXCLUSION CRITERIA: age <18 years, neuromuscular or congenital scoliosis, cervical or cervicothoracic fusions, nonelective conditions (infection, tumor, trauma). Instrumented fusions were classified by the Scoliosis Research Society-Schwab ASD classification. Statistical analysis consisted of descriptives (measures of central tendency, dispersion, frequencies), independent Student t tests, χ2, analysis of variance, and logistic regression to determine association of implant density [(number of screws + number of hooks)/surgical levels of fusion] and PJK. Mean and median follow-up was 2.8 and 2.7 years, respectively. RESULTS: Eighty-three patients (17 male, 66 female) with a mean age of 59.7 years (standard deviation, 10.3) were analyzed. Mean body mass index (BMI) was 29.5 kg/m2 (range, 18-56 kg/m2) with mean preoperative Oswestry Disability Index of 48.67 (range, 6-86) and mean preoperative sagittal vertical axis of 8.42. The mean levels fused were 9.95 where 54 surgeries had interbody fusion. PJK prevalence was 21.7%, and pseudoarthrosis was 19.3%. Mean postoperative Oswestry Disability Index was 27.4 (range, 0-74). Independent Student t tests showed that PJK was not significant for age, gender, BMI, rod type, mean postoperative sagittal vertical axis, or Scoliosis Research Society-Schwab ASD classification; but iliac fixation approached significance (P = 0.077). Implant density and postoperative lumbar lordosis (LL) were predictors for PJK (P = 0.018 and 0.045, respectively). Controlling for age, BMI, and gender, postoperative LL (not implant density) continued to show significance in multivariate logistic regression model. CONCLUSIONS: PJK, although influenced by a multitude of factors, may be statistically related to implant density and LL.

Ruptured traumatic vertebral artery pseudoaneurysm in a child treated with trapping and posterior inferior cerebellar artery reimplantation. Case report and review of the literature.

The authors present the case report of a pediatric patient with a ruptured traumatic pseudoaneurysm of the intracranial vertebral artery (VA) from which the posterior inferior cerebellar artery (PICA) emerged. After considering multiple therapeutic options, the patient was treated surgically by trapping of the aneurysm segment and direct reimplantation of the PICA distal to the rupture site. In addition to presenting this unique case, the authors discuss the treatment of VA pseudoaneurysms and the various techniques for PICA revascularization. A review of the literature on PICA reimplantation is provided as an adjunct in the treatment of complex VA aneurysms.

Development of a de novo cerebral arteriovenous malformation in a child with sickle cell disease and moyamoya arteriopathy. Case report.

The authors report the unique case of a 6-year-old African-American girl with sickle cell disease (SCD) and an associated moyamoya arteriopathy who developed a de novo arteriovenous malformation (AVM) of the cerebral circulation. Based on preoperative cerebral angiography, computerized tomography angiography, and magnetic resonance imaging, the incidentally discovered lesion was originally thought to be a direct arteriovenous fistula with an associated varix. At surgery, however, a 1.5-cm AVM was identified adjacent to the deep surface of the varix, and it was successfully resected. The diagnosis of cerebral AVM was then confirmed histopathologically. Based on a review of the literature, no published correlation between cerebral AVMs and SCD exists. In addition to reporting this case, the authors provide a description of AVM pathogenesis, with particular emphasis on acquired AVMs of the cerebral circulation.

Ruptured superior cerebellar artery aneurysm in a child with bilateral fibromuscular hyperplasia of the renal arteries: case report and review of the literature.

The authors report the case of a pediatric patient with bilateral fibromuscular hyperplasia (FMH) of the renal arteries who sustained a subarachnoid hemorrhage (SAH) caused by the rupture of a superior cerebellar artery aneurysm. The aneurysm was successfully treated with microsurgical clip occlusion. The association between renal artery FMH and aneurysmal SAH is extremely rare and incompletely understood. There are six previously published cases in the English literature; only one case involved direct aneurysm treatment and none involved the posterior circulation. In addition to presenting this case, the authors discuss the complexities involved in treating these patients from a technical and conceptual standpoint.

Late morphological progression of a dissecting basilar artery aneurysm after staged bilateral vertebral artery occlusion: case report.

BACKGROUND: The authors present a patient who experienced late (5-year follow-up) morphological progression of a dissecting aneurysm of the distal basilar artery after treatment with a combined microsurgical and neuroendovascular Hunterian strategy. In addition to postulating about the possible reasons underlying the evolution of this lesion, the role of stenting is discussed. CASE DESCRIPTION: The patient was 37 years old when she suffered a subarachnoid hemorrhage from spontaneous basilar artery dissection. At the time of the hemorrhage, minimal aneurysmal enlargement was noted angiographically, and she was therefore treated nonoperatively. On reimaging 5 months later, massive enlargement of the aneurysm was noted. The patient was treated with staged bilateral vertebral artery sacrifice using a combination of microsurgical and neuroendovascular techniques. The dominant vertebral artery was clip-ligated distal to the posteroinferior cerebellar artery, whereas the contralateral vertebral artery was coil-occluded cervically 1 week later. CONCLUSIONS: Despite the patient remaining asymptomatic, follow-up angiography 5 years after the initial hemorrhage revealed further enlargement of the aneurysm as well as a newly discovered inferiorly projecting daughter sac measuring 5 mm in diameter. Clearly, certain aneurysms exist for which indirect approaches involving hemodynamic attenuation fail to prevent progression. With greater refinements in stent technology, such lesions may be more effectively treated.

Transarterial coil embolization of a high-flow vertebrojugular fistula due to penetrating craniocervical trauma: case report.

BACKGROUND: Vertebrojugular fistulas after penetrating cervical trauma (gunshot or stab wounds) are rarely reported. Successful endovascular coil embolization of an acute fistulizing vertebral artery pseudoaneurysm involving an obstructed internal jugular vein is presented and the various treatment strategies for such a lesion are described. CASE DESCRIPTION: A 23-year-old man presented from an outside institution after sustaining 2 gunshot wounds in a civilian conflict. Neuroimaging revealed a right vertebral artery pseudoaneurysm, which formed a fistulous connection with the internal jugular vein. Because venous outflow obstruction was present just below the fistula, a high-flow shunt was directed intracranially. Both the pseudoaneurysm and arteriovenous fistula were accessed percutaneously via a transfemoral route and coil embolization was performed. Perfusion of the basilar artery circulation was assumed by the contralateral vertebral artery. The ipsilateral posteroinferior cerebellar artery filled through retrograde flow down the vertebral confluence. CONCLUSIONS: Coil embolization is a safe and reliable strategy by which to obliterate an acute traumatic vertebrojugular fistula as well as pseudoaneurysm. Serial angiographic follow-up is mandatory to document a persistent cure.

Microsurgical resection of infratentorial arteriovenous malformations.

Successful microsurgical resection of an infratentorial arteriovenous malformation (AVM) requires both surgical skill and intraoperative judgment. Extensive practical experience in treating these complex lesions, which is acquired over many years, is of substantial value during each new operation. The authors present the surgical approaches and techniques used for the treatment of posterior fossa AVMs based largely on the strategies acquired and developed by the senior author (H.H.B.). Emphasis is placed on conceptual principles of AVM excision, as well as principles incorporated for the treatment of each specific type of infratentorial malformation.

Time to Event Analysis for the Development of Venous Thromboembolism After Spinal Fusion ≥ 5 Levels.

OBJECTIVE: Venous thromboembolism (VTE) is an important complication after spine surgery with an incidence of 31%. To our knowledge, no study has reported a time-dependent examination of factors influencing VTE. We report factors influencing first and multiple VTE events and perform a time-dependent analysis. METHODS: A retrospective analysis was performed of consecutive, "high-risk" patients receiving multilevel spinal fusion and an inferior vena cava (IVC) filter during the period 2000-2008. Descriptive statistics and frequencies were examined. Student t tests and logistic regression analysis identified confounders influencing development of acute VTE. Kaplan-Meier survival and Cox proportional hazard model evaluated time-dependent risk factors. Multivariate linear regression model analyzed multiple acute VTE events. RESULTS: There were 218 patients (149 women and 69 men) with an average age of 59.2 years (range, 18-86 years) who had 252 hospitalizations with an average stay of 20.3 days (SD = 15.6). There were 72 VTE events, with mean time to VTE of 15 days (SD = 18.1). Logistic regression identified factors influencing development of acute VTE, including sex (P = 0.04, OR = 0.243), VTE history (P = 0.001, OR = 8.0), IVC filter type (P = 0.050, OR = 15.6), chemoprophylaxis (P = 0.013, OR = 0.82), and hospital stay (P < 0.001, OR = 0.16). Kaplan-Meier curve revealed VTE history increased the rate of VTE development (P = 0.003). Cox proportional hazard model demonstrated IVC filter type (P = 0.003, hazard ratio = 5.042) and VTE history (P = 0.001, hazard ratio = 4.187) were significant for first VTE events. Linear regression analysis identified factors influencing development of multiple VTE events during a hospitalization, including VTE history (P < 0.01), chemoprophylaxis (P = 0.003), IVC filter type (P = 0.015), and hospital stay (P < 0.001). Mean and median follow-up were 3.3 years and 2.8 years, respectively. CONCLUSIONS: Sex, VTE history, IVC filter type, chemoprophylaxis, and hospital stay influenced development of VTE. Time to VTE correlated with DVT history and IVC filter type, whereas VTE history and hospital stay influenced multiple VTE events.

Predicting Kyphosis Correction During Posterior-Only Vertebral Column Resection by the Amount of Spinal Column Shortening.

STUDY DESIGN: Retrospective. OBJECTIVE: To investigate the relationship between the amount of correction achieved (K°) and extent of vertebral column shortening (mm) with posterior vertebral column resection (PVCR). SUMMARY OF BACKGROUND DATA: There is no scientific reference to the correlation between K° and column shortening (mm) with PVCR. METHODS: Based on simple geometry, we tested the hypothesis that we could predict the amount of actual kyphosis correction (K°) by calculation on 26 kyphotic PVCR patients. Using multiple linear measurements (mm), two angular approximations (°) were calculated: the geometric approximation (G°) using the geometric calculation (G-cal), and the rough approximation (R°) by more simplistic calculation (R-cal). Both G° and R° were compared against K° as measured on the pre- and postoperative radiographs. If calculated G° and R° is close to measured K°, we can use the calculations (G-cal and R-cal) in the clinical situation. RESULTS: The mean correction of K° was 38°. K°-G° and K°-R° were not significantly greater than 3° and 6°, respectively. As K° was very close to G° and R°, K° can replace G° and R°. Therefore, we can use G-cal and R-cal in the clinical setting and we can determine how much posterior shortening and what cage size is required to obtain a certain amount of K°. CONCLUSIONS: With two calculations (G-cal & R-cal), we can determine how much vertebral column shortening (mm) we need during PVCR to obtain the amount of kyphosis correction desired (K°). In order to obtain K°, using the formula deduced from G-cal and R-cal, we can determine the shortening between the upper and lower pedicle screws and cage size.

Extended lateral transsylvian approach for basilar bifurcation aneurysms.

The surgical management of aneurysms of the basilar apex is one of the most challenging areas in neurosurgery. Successful treatment of this subgroup of aneurysms is dependent on the mastery of technical nuances that have been pioneered and advanced over the past 4 decades. Although both the traditional transsylvian and subtemporal approaches have distinct advantages, each is associated with significant limitations. In this article, the senior author shares his insights into a hybrid approach: the extended lateral transsylvian approach. This approach combines the assets of the two traditional approaches while eliminating their liabilities.

Selective cerebral revascularization as an adjunct in the treatment of giant anterior circulation aneurysms.

Cerebral revascularization, an indispensable component of neurovascular surgery, has been performed in the treatment of cranial base tumors, complex cerebral aneurysms, and occlusive cerebrovascular disease. The goal of a revascularization procedure is to augment blood flow distally. It can therefore be used as an adjunctive measure in the treatment of complex neurosurgical disease processes that require parent artery sacrifice for definitive treatment. In the treatment of giant anterior circulation aneurysms, for instance, a cerebral revascularization procedure may be considered in patients in whom the collateral circulation is marginal and in whom lesions may be treated either using a Hunterian-based strategy or clip-assisted reconstruction requiring a prolonged period of temporary occlusion. To date, there is no entirely effective method known to produce long-term tolerance to carotid artery (CA) sacrifice and, largely for that reason, some neurovascular surgeons advocate universal revascularization. The authors of this report, however, prefer to perform revascularization only in the limited subset of patients in whom preoperative assessment has revealed risk factors for cerebral ischemia due to hypoperfusion. In this paper, the authors introduce their protocol for assessing cerebrovascular reserve capacity, indications for cerebral revascularization in the treatment of complex anterior circulation aneurysms, and discuss their rationale for choosing to practice selective, rather than universal, revascularization.

Surgical strategies for vertebral osteomyelitis and epidural abscess.

Pyogenic vertebral discitis and osteomyelitis (PVDO) has become an increasing problem for the spine surgeon. Despite recent advances in medical care and improved diagnostic neuroimaging, PVDO remains a major cause of illness and death in the elderly population. Infection of the spinal column often presents insidiously; however, if not treated appropriately and in a timely manner it can lead to severe neurological impairment, systemic septicemia, and progressive spinal deformity. In this paper the authors review the epidemiological and pathophysiological features and the clinical presentation of PVDO. Conventional medical therapy is described, with a particular focus on the methods of diagnosis. Surgical strategies for PVDO are then presented based on the literature and according to the practice of the senior author (S.L.O.), with an emphasis placed on structural considerations, implant selection, and techniques for augmenting vascular tissue to the site of infection.