Use of allograft bone for posterior C1–2 fusion

Object

An iliac crest autograft is the gold standard for bone grafting in posterior atlantoaxial arthrodesis but can be associated with significant donor-site morbidity. Conversely, an allograft has historically performed suboptimally for atlantoaxial arthrodesis as an onlay graft. The authors have modified a bone grafting technique to allow placement of a bicortical iliac crest allograft in an interpositional manner, and they evaluated it as an alternative to an autograft in posterior atlantoaxial arthrodesis.

Methods

The records of 89 consecutive patients in whom C1–2 arthrodesis was performed between 2001 and 2005 were reviewed.

Results

Forty-seven patients underwent 48 atlantoaxial arthrodeses with an allograft (mean follow-up 16.1 months, range 0–49 months), and 42 patients underwent autograft bone grafting (mean follow-up 17.6 months, range 0–61.0 months). The operative time was 50 minutes shorter in the allograft (mean 184 minutes, range 106–328 minutes) than in the autograft procedure (mean 234 minutes, range 154–358 minutes), and the estimated blood loss was 50% lower in the allograft group than in the autograft group (mean 103 ml [range 30–200 ml] vs mean 206 ml [range 50–400 ml], respectively). Bone incorporation was initially slower in the allograft than in the autograft group but equalized by 12 months postprocedure. The respective fusion rates after 24 months were 96.7 and 88.9% for autografts and allografts. Complications at the donor site occurred in 16.7% of the autograft patients, including 1 pelvic fracture, 1 retained sponge, 1 infection, 2 hernias requiring repair, 2 hematomas, and persistent pain.

Conclusions

The authors describe a technique for interpositional bone grafting between C-1 and C-2 that allows for the use of an allograft with excellent fusion results. This technique reduced the operative time and blood loss and eliminated donor-site morbidity.

Perineural Spread of Malignant Mesothelioma Resulting in an Intradural Spinal Cord Mass: Case Report

Spinal cord involvement by perineural spread of malignant mesothelioma is rare. We report a case of malignant mesothelioma that spread locally to invade the bony spine with both extradural and intradural perineural spread into the spinal canal that resulted in spinal cord compression. A 61-year-old man with a history of malignant mesothelioma presented with progressive leg weakness and right-sided arm weakness. Magnetic resonance imaging showed an enhancing lesion in the apex of the right lung with extension through the C7-T1 foramina with right hemicord enhancement. The patient underwent a C7-T1 laminectomy and right-sided C7-T1 and T1-T2 foraminotomies for neural decompression and biopsy of the lesion. Intraoperatively, tumor extended epidurally, and intradural perineural tumor spread along the C8 and T1 nerve roots into the spinal cord. Because it adhered to the spinal cord, no dissectible plane could be identified that would allow for safe total removal of the tumor. The epidural portion of the tumor, the adjacent involved bone, and the T1 nerve root were resected. Pathologic examination revealed malignant mesothelioma with bony invasion and perineural spread along the T1 nerve root. After decompression of the spinal cord, the patient had moderate improvement of his hand and leg function. Perineural spread of malignant mesothelioma resulting in spinal cord compression is an unusual clinical presentation. Intimate involvement of the spinal cord may prohibit aggressive tumor resection.

Meningioangiomatosis associated with neurofibromatosis: report of 2 cases in a single family and review of the literature

BACKGROUND

Meningioangiomatosis (MA) is a rare benign disorder. It may occur sporadically or in association with neurofibromatosis (NF). The sporadic type typically presents with seizures, whereas that associated with NF is often asymptomatic. Of the 100 cases reported, only 14 are associated with NF. We now report 2 additional cases of MA associated with neurofibromatosis 2 (NF2) in a single family, with one occurring in the cerebellum. The etiology, pathology, and imaging features of MA are presented.

CASE DESCRIPTION

A 38-year-old woman (patient 1) presented with a 4-month history of ataxia. She had been diagnosed previously with NF2. Magnetic resonance imaging (MRI) scans of the brain revealed bilateral acoustic neuromas and multiple calcified intracranial lesions. Her 13-year-old daughter (patient 2) presented with complex partial seizures. MRI scans of the brain revealed bilateral acoustic neuromas and a right parietal mass. Patient 1 underwent a suboccipital craniotomy to resect the right-sided acoustic neuroma. A small portion of normal-appearing cerebellar cortex was resected to avoid undue retraction. Histopathologic examination showed the presence of a lesion consistent with MA. Patient 2 underwent a right temporal-parietal craniotomy to remove the enhancing epileptogenic right posterior temporoparietal lesion. Histopathologic analysis showed a lesion consistent with meningioma and MA.

CONCLUSIONS

MA has been reported infrequently in association with NF2. We now report 2 cases of MA associated with NF2 in one family, and we add the cerebellum to possible locations of occurrence. MA should be considered in the differential diagnosis of cortical lesions, particularly in patients with NF2.

History of instrumentation for stabilization of the subaxial cervical spine

In the past several decades methods have been developed to stabilize the subaxial cervical spine both posteriorly and anteriorly. Methods of posterior stabilization have progressed from interspinous wiring, through facet wiring and sublaminar wiring, to the lateral mass screws with plates and rods that are in use today. Plates for anterior stabilization have evolved from rigid plates requiring bicortical screws through those used with unicortical locking screws, to dynamic load-sharing plates used with variable angle screws. The original description of spinous process wiring was published by Hadra in 1891. In 1942 Rogers described the interspinous wiring method used for trauma-induced cervical instability, which was modified by Bohlman in 1985 (triple wiring technique). Luque rods with sublaminar wires were introduced in the late 1970s to address multilevel and occipitocervical instability. Facet wiring was developed in 1977 by Callahan to address the problem of stabilization when laminae are not present. Wiring remained the method used until Roy-Camille introduced the lateral mass screw-plate construct in the 1980s. The first plate for anterior stabilization was designed by Orozco and Llovet in 1970 and was later refined by Caspar; this was a rigid plate with bicortical screws. Morscher devised unicortical locking screws in the 1980s. The latest concept of dynamic load-sharing plates with variable angle screws was developed in 2000. In this article historical landmarks in surgical methods for the stabilization of the subaxial cervical spine are reviewed.

Long-term management of bilateral metastases of renal cell carcinoma to the choroid plexus

BACKGROUND

Metastatic tumors to the brain presenting exclusively in the choroid plexus are exceedingly rare. These events are frequently associated with renal cell carcinoma (RCC), of which all reported cases have been solitary lesions.

METHODS

The authors present the unusual case of a patient with metastatic RCC who developed bilateral tumors of the choroid plexus. These tumors, one of which was confirmed to be metastatic RCC by histologic analysis, were treated over a 5-year period with a combination of interventions, including surgical resection, stereotactic radiosurgery, and chemotherapy, in conjunction with continual radiological monitoring.

FINDINGS

Follow-up over a 5-year period demonstrated good control of the patient's intracranial disease and very little neurologic sequelae.

INTERPRETATION

This strategy was successful in keeping the patient in good health with minimal neurological symptoms, despite the bilateral nature of the disease and its generally poor prognosis.

Widespread central nervous system cavernous malformations associated with café-au-lait skin lesions. Case report

The simultaneous presence of cavernous malformations in the brain and spinal cord is a very rare finding and is typically associated with familial cavernous malformations. Although they are uncommon, various skin lesions can manifest in patients with familial cavernous malformations. The authors report on a 60-year-old man in whom more than 100 lesions consistent in appearance with cavernous malformations, including several intramedullary spinal cord lesions, were found throughout the neuraxis. This patient also displayed prominent café-au-lait skin lesions, but had no additional signs of neurofibromatosis or other neurocutaneous disorders. Analysis of his DNA revealed a novel mutation in the KRIT1/CCM1 gene, thereby confirming the diagnosis of familial cavernous malformation. The presence of these lesions in every major compartment of this patient's central nervous system underscores their indiscriminate nature and the need to screen throughout the neuraxis in patients in whom familial cavernous malformations are suspected. The findings in this case add to the growing list of skin lesions associated with genetically confirmed familial cavernous malformations. In patients presenting with seizures, focal neurological deficits, or hemorrhagic stroke, the presence of unusual skin lesions should prompt consideration of familial cavernous malformations, and appropriate screening should be performed.

Treatment of an anterior communicating artery aneurysm through an anomalous anastomosis from the cavernous internal carotid artery

Cavernous internal carotid artery (ICA)-anterior cerebral artery (ACA) anastomoses are unusual anomalies in which a duplicated A, segment of the ACA arises from the infraoptic ICA. The authors report on a 30-year-old woman who presented with subarachnoid hemorrhage from an anterior communicating artery (ACoA) aneurysm associated with an extremely rare variant of this anastomosis. The extra A, segment emerged from the ICA within the cavernous sinus rather than at or above the level of the ophthalmic artery. The presence of the anomalous vessel provided a straightforward endovascular approach to the ACoA and allowed the use of coil placement rather than surgical clipping to treat the aneurysm successfully.