Sublaminar fixation for traumatic lumbar fracture subluxation with lateral listhesis in a 2-year-old patient.

Pediatric spinal trauma can present a surgeon with difficult management decisions given the rarity of these cases, pediatric anatomy, and a growing spine. The need to stabilize a traumatically unstable pediatric spine can be an operative challenge given the lack of instrumentation available. The authors present a surgical technique and an illustrative case that may offer a novel, less disruptive method of stabilization. A 2-year-old girl presented after an assault with an L1-2 fracture subluxation with lateral listhesis and fractured jumped facets exhibited on CT scans. CT also showed intact growth plates at the vertebral body, pedicles, and posterior elements. MRI showed severe ligamentous injury, conus medullaris compression, and an epidural hematoma. Neurologically, the patient moved both lower extremities asymmetrically. Given the severity of the deformity and neurological examination and disruption of the stabilizing structures, the authors made the decision to surgically decompress the L-1 and L-2 segments with bilateral laminotomies, evacuate the epidural hematoma, and reduce the deformity with sublaminar stabilization using braided polyester cables bilaterally, thus preserving the growth plates. They also performed a posterolateral onlay fusion at L-1 and L-2 using autograft and allograft placed due to the facet disruption. At the 42-month follow-up, imaging showed fusion of L-1 and L-2 with good alignment, and the hardware was subsequently explanted. The patient was neurologically symmetric in strength, ambulating, and had preserved alignment. Her bones and spinal canal continued to grow in relation to the other levels.

Intracranial Myeloid Sarcoma Metastasis Mimicking Acute Subdural Hematoma.

Myeloid sarcoma, a rare consequence of myeloproliferative disorders, is rarely seen in the central nervous system, most commonly in the pediatric population. Although there are a handful of case reports detailing initial presentation of CNS myeloid sarcoma in the adult population, we have been unable to find any reports of CNS myeloid sarcoma presenting as a large mass lesion in a herniating patient. Here, we present the case of a patient transferred to our facility for a very large subdural hematoma. Based on imaging characteristics, it was felt to be a spontaneous hematoma secondary to coagulopathy. No coagulopathy was found. Interestingly, he did have a history of acute myeloid leukemia (AML) diagnosed 2 months previously, and intraoperatively he was found to have a confluent white mass invading both the subdural and subarachnoid spaces. There was minimal associated hemorrhage and final pathology showed myeloid sarcoma. This is the first report we are aware of in which CNS myeloid sarcoma presented as a subdural metastasis and also the first report in which we are aware of this etiology causing a herniation syndrome secondary to mass effect.

Improving C1-C2 Complex Fusion Rates: An Alternate Approach.

The surgical repair of atlantoaxial instabilities (AAI) presents complex and unique challenges, originating from abnormalities and/or trauma within the junction regions of the C1-C2 atlas-axis, to surgeons. When this region is destabilized, surgical fusion becomes of key importance in order to prevent spinal cord injury. Several techniques can be utilized to provide for the adequate fusion of the atlantoaxial construct. Nevertheless, many individuals have less than ideal rates of fusion, below 35%-40%, which also involves the C2 nerve root being sacrificed. This suboptimal and unavoidable iatrogenic complication results in the elevated probability of complications typically composed of vertebral artery injury. This review is a retrospective analysis of 87 patients from Cedars Sinai Medical Center in Los Angeles, California, who had the C1-C2 surgical fusion procedure performed within the time frame from 2001 to 2008, with a mean follow-up period of three years. These patients had presented with typical AAI symptoms of fatigability, limited mobility, and clumsiness. Diagnosis of C1-C2 instability was documented via radiographic studies, typically utilizing computed tomography (CT) scans or x-rays. All patients had bilateral C1 lateral masses and C2 pedicle screws. In addition, the C1-C2 joint was accessed by retracting the C2 nerve root superiorly and exposing the joint by utilizing a high-speed burr. The cavity that is developed within the joint is packed with local autologous bone from the cephalad resection of the C2 laminae. Fusion of the C1-C2 joint was achieved in all patients and a final follow-up was conducted approximately three years postoperative. Of the 87 patients, two presented with occipital headaches resulting from the C1 screws impinging on the C2 nerve root. The issue was rectified by removing instrumentation in both patients after documenting complete fusion via radiographic studies, with complete resolution of symptoms. No vertebral artery or spinal cord injuries were reported as a result of the minor complication. Overall, we aim to describe a safe and reliable alternative technique to fuse C1-C2 instability by focusing on intra-articular arthrodesis complementing instrumentation fixation. This methodology is advantageous from a biomechanical standpoint secondary to axial loading, as well as the large surface area available for arthrodesis. Additionally, this technique does not involve the resection of the C2 nerve root, resulting in low risk for vertebral artery or spinal cord injury.

Stereotactic robot-assisted MRI-guided laser thermal ablation of radiation necrosis in the posterior cranial fossa: technical note.

Laser interstitial thermal therapy (LITT) is a minimally invasive procedure used to treat a variety of intracranial lesions. Utilization of robotic assistance with stereotactic procedures has gained attention due to potential for advantages over conventional techniques. The authors report the first case in which robot-assisted MRI-guided LITT was used to treat radiation necrosis in the posterior fossa, specifically within the cerebellar peduncle. The use of a stereotactic robot allowed the surgeon to perform LITT using a trajectory that would be extremely difficult with conventional arc-based techniques. A 60-year-old man presented with facial weakness and brainstem symptoms consistent with radiation necrosis. He had a history of anaplastic astrocytoma that was treated with CyberKnife radiosurgery 1 year prior to presentation, and he did well for 11 months until his symptoms recurred. The location and form of the lesion precluded excision but made the patient a suitable candidate for LITT. The location and configuration of the lesion required a trajectory for LITT that was too low for arc-based stereotactic navigation, and thus the ROSA robot (Medtech) was used. Using preoperative MRI acquisitions, the lesion in the posterior fossa was targeted. Bone fiducials were used to improve accuracy in registration, and the authors obtained an intraoperative CT image that was then fused with the MR image by the ROSA robot. They placed the laser applicator and then ablated the lesion under real-time MR thermometry. There were no complications, and the patient tolerated the procedure well. Postoperative 2-month MRI showed complete resolution of the lesion, and the patient had some improvement in symptoms.

Early optical detection of cerebral edema in vivo.

OBJECT: Cerebral edema is a significant cause of morbidity and mortality in diverse disease states. Currently, the means to detect progressive cerebral edema in vivo includes the use of intracranial pressure (ICP) monitors and/or serial radiological studies. However, ICP measurements exhibit a high degree of variability, and ICP monitors detect edema only after it becomes sufficient to significantly raise ICP. The authors report the development of 2 distinct minimally invasive fiberoptic near-infrared (NIR) techniques able to directly detect early cerebral edema. METHODS: Cytotoxic brain edema was induced in adult CD1 mice via water intoxication by intraperitoneal water administration (30% body weight intraperitoneally). An implantable dual-fiberoptic probe was stereotactically placed into the cerebral cortex and connected to optical source and detector hardware. Optical sources consisted of either broadband halogen illumination or a single-wavelength NIR laser diode, and the detector was a sensitive NIR spectrometer or optical power meter. In one subset of animals, a left-sided craniectomy was performed to obtain cortical biopsies for water-content determination to verify cerebral edema. In another subset of animals, an ICP transducer was placed on the contralateral cortex, which was synchronized to a computer and time stamped. RESULTS: Using either broadband illumination with NIR spectroscopy or single-wavelength laser diode illumination with optical power meter detection, the authors detected a reduction in NIR optical reflectance during early cerebral edema. The time intervals between water injection (Time Point 0), optical trigger (defined as a 2-SD change in optical reflectance from baseline), and defined threshold ICP values of 10, 15 and 20 mm Hg were calculated. Reduction in NIR reflectance occurred significantly earlier than any of the ICP thresholds (p < 0.001). Saline-injected control mice exhibited a steady baseline optical signal. There was a significant correlation between reflectance change and tissue specific gravity of the cortical biopsies, further validating the dual-fiberoptic probe as a direct measure of cerebral edema. CONCLUSIONS: Compared with traditional ICP monitoring, the aforementioned minimally invasive NIR techniques allow for the significantly earlier detection of cerebral edema, which may be of clinical utility in the identification and thus early treatment of cerebral edema.

Wilder Penfield, Pío del Río-Hortega, and the discovery of oligodendroglia.

OBJECTIVE: To describe the contribution of Wilder Penfield to the early characterization of glial cells in collaboration with Pío Del Río-Hortega and Santiago Ramón y Cajal during his study in La Residencia des Estudiantes, Laboratorio de Histopatología in Madrid in 1924. METHODS: Comprehensive review of the English and Spanish-language literature pertinent to the history of Wilder Penfield (1891-1976), his associations with Pío Del Río-Hortega (1882-1945) and Santiago Ramón y Cajal (1852-1934), and his articles describing glial cells. RESULTS: Penfield went to Spain in the spring of 1924 to work with Río-Hortega and Cajal, which resulted in a fruitful 5 months of study. During this trip, he published several articles, including a landmark report in which he completed the characterization of the "third element" of Cajal (non-astrocyte glial cells) and its relationship to classical neuroglia. The article was accepted for publication in Brain, the leading British neurology journal of the time. CONCLUSION: Today, Wilder Penfield is much better known for his seminal explorations of the cortical basis of higher function, his contributions to epilepsy surgery, and as the founder of the Montreal Neurological Institute than for his original work with Sherrington in England or Río-Hortega and Cajal in Spain. While working with Río-Hortega, his report on oligodendroglia was critical to advancing the characterization of this important class of glial cells.