Anthony M. Avellino

Biomarkers: Mining the Biofluid Proteome

Proteomics has brought with it the hope of identifying novel biomarkers for diseases such as cancer. This hope is built on the ability of proteomic technologies, such as mass spectrometry (MS), to identify hundreds of proteins in complex biofluids such as plasma and serum. There are many factors that make this research very challenging beginning with the lack of standardization of sample collection and continuing through the entire analytical process. Fortunately the advances made in the characterization of biofluids using proteomic techniques have been rapid and suggest that these mainly discovery driven approaches will lead to the development of highly specific platforms for diagnosing diseases and monitoring responses to different treatments in the near future.

Differential Macrophage Responses in the Peripheral and Central Nervous System during Wallerian Degeneration of Axons

We characterized quantitatively the macrophage response following axonal injury in both the peripheral (PNS) and central nervous system (CNS) of adult mammals. A monoclonal antibody (ED-1) which stains monocytes, macrophages, and activated microglia was employed. In one model, Wallerian degeneration of the sciatic nerve was studied. An increase in the number of macrophages was seen as early as 1 day following nerve transection. Macrophage number increased synchronously along the length of degenerating nerve over a 21-day period. In a second model, transection of a spinal dorsal sensory root allowed us to compare and contrast the macrophage response along the PNS and CNS portions of a single axonal pathway. An increased number of macrophages restricted to the PNS portion of this pathway was seen by 3 days and continued to increase over a 14-day period. Myelin breakdown occurred in association with an increase in the number of macrophages by 3 days in the PNS but not the CNS portion of the degenerating dorsal root axon pathway. Low-affinity nerve growth factor receptor immunohistochemical staining increased by Day 1 in the PNS but not the CNS portion of this pathway, occurring prior to the invasion of macrophages. In both models, the morphology of infiltrating macrophages changed over time from small slender ramified cells to large elongated multivacuolated cells. In conclusion, our results demonstrate that the macrophage response during Wallerian degeneration of axons in adult mammals is much more rapid and robust in the PNS, where axonal regeneration occurs, than in the CNS, where axonal regeneration is far more limited.

Complement Depletion Reduces Macrophage Infiltration and Activation during Wallerian Degeneration and Axonal Regeneration

After peripheral nerve injury, macrophages infiltrate the degenerating nerve and participate in the removal of myelin and axonal debris, in Schwann cell proliferation, and in axonal regeneration.In vitro studies have demonstrated the role serum complement plays in both macrophage invasion and activation during Wallerian degeneration of peripheral nerve. To determine its rolein vivo, we depleted serum complement for 1 week in adult Lewis rats, using intravenously administered cobra venom factor. At 1 d after complement depletion the right sciatic nerve was crushed, and the animals were sacrificed 4 and 7 d later. Macrophage identification with ED-1 and CD11a monoclonal antibodies revealed a significant reduction in their recruitment into distal degenerating nerve in complement-depleted animals. Complement depletion also decreased macrophage activation, as indicated by their failure to become large and multivacuolated and their reduced capacity to clear myelin, which was evident at both light and electron microscopic levels. Axonal regeneration was delayed in complement-depleted animals. These findings support a role for serum complement in both the recruitment and activation of macrophages during peripheral nerve degeneration as well as a role for macrophages in promoting axonal regeneration.

Bacterial meningitis associated with lumbar drains: a retrospective cohort study

OBJECTIVES The infective potential of lumbar drainage is an important topic deserving particular study. The aetiology, incidence, and clinical findings associated with bacterial meningitis are described in patients having continuous lumbar CSF drainage to treat communicating hydrocephalus after subarachnoid haemorrhage or CSF leaks after traumatic dural rents. METHODS Retrospective review of the records of patients with a positive CSF bacterial culture who underwent lumbar drain placement over a 39 month period. RESULTS Thirteen cases of bacterial meningitis occurred subsequent to the use of 312 lumbar drain kits (4.2%). All meningitic patients had CSF pleocytosis, but not all had peripheral leukocytosis. Fever, peripheral leukocytosis, and CSF pleocytosis did not help to differentiate the presence of bacterial meningitis from other infections. Eight patients had prior CSF drainage procedures, including ventriculostomy (n=5) or lumbar drain (n=5) placements; two patients received both procedures. Six of 13 patients developed their CSF infection within 24 hours of lumbar drain insertion. Six of 13 patients developed meningitis while receiving antibiotics for other reasons. CONCLUSIONS External lumbar drainage seems to carry a low risk of infectious meningitis and offers a safe alternative to ventriculostomy or serial lumbar punctures. Antibiotics do not seem to protect completely against developing the infection. The infection happens most often with skin organisms. The meningitis often appears within 24 hours after lumbar drain placement. Daily CSF samples should include bacterial cultures but cell counts may not offer any additional useful information in diagnosing the complication. Lumbar drain insertion and management need not be confined to the intensive care unit.

Ultrasound Accelerates Functional Recovery after Peripheral Nerve Damage

OBJECTIVE Axonal injury in the peripheral nervous system is common, and often it is associated with severe long-term personal and societal costs. The objective of this study is to use an animal model to demonstrate that transcutaneous ultrasound can accelerate recovery from an axonotmetic injury. METHODS The sciatic nerve of adult male Lewis rats was crushed in the right midthigh to cause complete distal degeneration of axons yet maintain continuity of the nerve. Beginning 3 days after surgery, various transcutaneous ultrasound treatments or sham treatments were applied 3 days per week for 30 days to the crush site of rats that were randomly assigned to two groups. In the preliminary experiments, there were three animals in each ultrasound group and two control animals. In the final experiment, there were 22 animals in the ultrasound group and 20 animals in the control group. Recovery was assessed by use of a toe spread assay to quantify a return to normal foot function in the injured leg. Equipment included a hand-held transducer that emitted continuous-wave ultrasound. The most successful ultrasound protocol had a spatial peak, time-averaged intensity of 0.25 W/cm2 operated at 2.25 MHz for 1 minute per application. RESULTS Rats subjected to the most successful ultrasound protocol showed a statistically significant acceleration of foot function recovery starting 14 days after injury versus 18 days for the control group. Full recovery by the ultrasound group occurred before full recovery by the control group. CONCLUSION Transcutaneous ultrasound applied to an animal model of axonotmetic injury accelerated recovery. Future studies should focus on identification of the mechanism(s) by which ultrasound creates this effect, as a prelude to optimization of the protocol, demonstration of its safety, and its eventual application to humans.

Spontaneous resolution of a cervicothoracic syrinx in a child. Case report and review of the literature.

A child with near complete spontaneous resolution of a cervicothoracic syrinx and improvement in a Chiari type I malformation without surgical intervention is presented. The child was followed clinically with serial magnetic resonance (MR) imaging and has remained neurologically stable over an 11-year period. To our knowledge, only 3 pediatric cases of spontaneous resolution of a spinal cord syrinx as documented by MR imaging without surgical intervention have been reported. This case contributes to the literature on the natural history of syringes.

Meningiomas in Children

Objective: Pediatric meningioma is a rare diagnosis. This retrospective review seeks to elucidate pertinent characteristics of pediatric patients presenting with meningioma. Methods: The Seattle Children’s Hospital and Regional Medical Center brain tumor database was surveyed from 1940 through 2004. Twenty patients were identified. Results: The median age of the 20 patients was 13 years. Five patients had radiation-induced meningiomas. Five patients had neurofibromatosis type 2. Ten patients had spontaneously arising meningiomas, 2 of which were malignant. Conclusion: Patients with spontaneously arising meningiomas were younger than those with identified risk factors. There was no recurrence in patients with radiation-induced meningiomas. The only death occurred in a patient with a malignant meningioma.

Management of Intrinsic Gliomas of the Tectal Plate in Children

The natural history, management, and long-term outcome for patients with benign, intrinsic tectal plate gliomas remain controversial in spite of their propensity to cause late-onset hydrocephalus. A 10-year retrospective review has identified 11 consecutive children with tectal plate lesions. Headache, vomiting, a decline in school performance, tremor, and complex partial seizures were common presenting symptoms. All patients presented with signs and symptoms of hydrocephalus. Magnetic resonance (MR) imaging delineated an intra-axial mass lesion of the midbrain primarily localized to the tectal plate which uniformly was hyperintense on T2-weighted imaging and had a more variable appearance on T1-weighted imaging and rare enhancement with gadolinium. No patient underwent surgical resection, chemotherapy, or radiotherapy. Three of 11 patients (27%) showed evidence of progression in size or a new focus of enhancement on MR imaging, which was clinically asymptomatic. In this series, no patient with a tectal plate lesion less than 1.5 cm in maximal diameter and without gadolinium enhancement showed any evidence of clinical or radiological progression. Although intrinsic tectal lesions in children are clinically indolent and the initial management consists of CSF diversion, these lesions may eventually progress and still warrant long-term follow-up with serial MR imaging.

Equivalence of fusion rates after rigid internal fixation of the occiput to C-2 with or without C-1 instrumentation

OBJECT The object of this study was to assess a multiinstitutional experience with pediatric occipitocervical constructs to determine whether a difference exists between the fusion and complication rates of constructs with or without direct C-1 instrumentation. METHODS Seventy-seven cases of occiput-C2 instrumentation and fusion, performed at 9 childrens hospitals, were retrospectively analyzed. Entry criteria included atlantooccipital instability with or without atlantoaxial instability. Any case involving subaxial instability was excluded. Constructs were divided into 3 groups based on the characteristics of the anchoring spinal instrumentation: Group 1, C-2 instrumentation; Group 2, C-1 and C-2 instrumentation without transarticular screw (TAS) placement; and Group 3, any TAS placement. Groups were compared based on rates of fusion and perioperative complications. RESULTS Group 1 consisted of 16 patients (20.8%) and had a 100% rate of radiographically demonstrated fusion. Group 2 included 22 patients (28.6%), and a 100% fusion rate was achieved, although 2 cases were lost to follow-up before documented fusion. Group 3 included 39 patients (50.6%) and demonstrated a 100% radiographic fusion rate. Complication rates were 12.5, 13.7, and 5.1%, respectively. There were 3 vertebral artery injuries, 1 (4.5%) in Group 2 and 2 (5.1%) in Group 3. CONCLUSIONS High fusion rates and low complication rates were achieved with each configuration examined. There was no difference in fusion rates between the group without (Group 1) and those with (Groups 2 and 3) C-1 instrumentation. These findings indicated that in the pediatric population, excellent occipitocervical fusion rates can be accomplished without directly instrumenting C-1.

Retrospective review of multilevel spinal fusion combined with spinal cord transection for treatment of kyphoscoliosis in pediatric myelomeningocele patients

Study Design. Retrospective review of cases at a single institution from 1998 to 2005. Objective. The authors present their surgical experience, complications, and learned insight in 9 myelomeningocele children with kyphoscoliosis treated with combined spinal cord transection and spinal fusion. Summary of Background Data. Complication rates in spinal fusion for treatment of kyphoscoliosis in myelomeningocele patients are high. Spinal cord transection in combination with fusion can be an appropriate strategy in selected patients, but changes in cerebrospinal fluid (CSF) dynamics that may accompany ligation of the distal CSF circulation are not well characterized. Methods. Demographic, clinical, and radiologic data were examined in 9 children with myelomeningocele level at or above T12 and no residual urologic function treated at our institution with spinal cord detethering and transection, and multilevel spinal fusion. Seven children underwent kyphectomy with posterior fusion only for severe gibbus deformities, while 2 had anterior and posterior fusions for severe kyphoscoliosis. Results. Follow-up of patients ranged from 4 to 92 months (mean, 37.8 months). Eight children (89%) experienced postoperative complications involving wound infection or skin breakdown. One child presented with a CSF leak. Two children (22%) required revision of their ventriculoperitoneal shunts. The average angle of kyphosis before surgery was 122.3 (range, 48°–180°), and the average postoperative angle was 38.2 (range, 4°–113°), with average correction being 81.9° (range, 29°–124). Average correction of scoliosis, if present, was 59.5° (range, 35°–92°). Conclusion. Combined spinal cord transection and spinal fusion allowed an average correction of kyphosis by 81.9°. The complication rate was 89%, with wound concerns being the most significant. Additionally, 22% of patients required shunt revision within 6 weeks of surgery. We attribute this to alteration of CSF dynamics resulting from loss of CSF absorption and flow-buffering capacity below the level of the spinal cord transection.