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Rene O. Sanchez-Mejia and Michael T. Lawton

✓Distal aneurysms of basilar perforating and circumferential arteries are exceedingly rare. The authors encountered one patient with a distal basilar perforating artery aneurysm and two with aneurysms arising from circumferential branches of the basilar artery (BA). The diagnostic features, microsurgical treatment, and outcomes in these three patients are described. The first patient, a 27-year-old man, presented with an angiogram-negative subarachnoid hemorrhage (SAH), and subsequent readmission for a new hemorrhage revealed a centrally thrombosed aneurysm arising from a basilar apex perforating artery. The second patient, a 68-year-old man, presented for follow-up evaluation 2 months after an angio-gram-negative SAH, and an aneurysm was identified on a circumferential artery originating from the BA trunk. The third patient, a 2-year-old boy, presented with blunt head trauma and a pseudoaneurysm arising from a basilar apex circumferential artery.

All three aneurysms were managed microsurgically with aneurysm trapping, via either an orbitozygomatic or an extended retrosigmoid approach. Occlusion of the distal perforating or circumferential artery was well tolerated in all cases, with no neurological sequelae resulting from surgery. Features common to all three aneurysms were dolichoectatic morphology, intraluminal thrombus, and SAH. These aneurysms may be difficult to diagnose given their small size and delayed filling on angiographic studies. Consequently, their presence in cases of angiogram-negative SAH may be underestimated. These aneurysms are not amenable to endovascular treatment, but excellent results can be obtained with microsurgical exposure and trapping.

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Jason S. Cheng, Rene O. Sanchez-Mejia, Mary Limbo, Mariann M. Ward and Nicholas M. Barbaro

Object

Trigeminal neuralgia (TN) is a painful disorder that frequently causes lancinating, electrical shock–like pain in the trigeminal distribution. Common surgical treatments include microvascular decompression (MVD), radio-surgery, and radiofrequency ablation, and complete pain relief is generally achieved with a single treatment in 70 to 85% of cases for all modalities. In a subset of patients with multiple sclerosis (MS), however, the rates of surgical treatment failure and the need for additional procedures are significantly increased compared with those in patients without MS. In this study the authors report their experience with a cohort of 11 patients with TN who also had MS, and assess the efficacy of MVD, gamma knife surgery (GKS), and radiofrequency ablation in achieving complete or partial long-term pain relief.

Methods

Eleven patients with TN and MS who were treated by the senior author (N.B.) at the University of California, San Francisco were included in this study. All patients underwent GKS and/or radiofrequency ablation, and four received MVD. A detailed clinical history and intraoperative findings were recorded for each patient and frequent follow-up evaluations were performed, with a mean follow-up duration of 40.6 months (range 1–96 months). Pain was assessed for each patient by using the Barrow Neurological Institute scale (Scores I–V).

Conclusions

Achieving complete pain relief in patients with TN and MS required significantly more treatments compared with all other patients with TN who did not have MS (p = 0.004). Even when compared with a group of 32 patients who had highly refractory TN, the cohort with MS required significantly more treatments (p = 0.05). Radiosurgery proved to be an effective procedure and resulted in fewer retreatments and longer pain-free intervals compared with MVD or radiofrequency ablation.

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René O. Sanchez-Mejia, Sravana K. Chennupati, Nalin Gupta, Heather Fullerton, William L. Young and Michael T. Lawton

Object

Young age is considered an important factor in determining outcomes after microsurgical resection of arteriovenous malformations (AVMs), but better results in children have not been adequately explained. A consecutive series of pediatric and adult patients was reviewed to determine whether differences in outcomes between these two groups were due to differences in AVM anatomy, rupture rates, neurological condition at presentation, treatment techniques, or other causes.

Methods

As assessed using the modified Rankin Scale (mRS), patient characteristics, clinical presentation, AVM anatomy, treatment techniques, and outcomes were compared between age groups. Thirty-two pediatric and 192 adult patients underwent microsurgical AVM resection during a 6.4-year period; complete resection was achieved in 97% of the children and 98% of adults. Superior outcomes were observed in children, who had better final mRS scores (p = 0.003) and more favorable changes in these scores (the condition of 94% of children improved or remained unchanged, compared with 70% of adults; p = 0.001). The change in the mean mRS scores was 1.31 for children and 0.14 for adults (p = 0.001). There were no significant clinical, anatomical, or therapeutic differences between children and adults.

Conclusions

This analysis confirms the observation that children fare better than adults after microsurgical AVM resection. This discrepancy cannot be explained by differences in AVM anatomy, lesion rupture rates, presenting neurological condition, or treatment techniques, leading the authors to infer that neural plasticity may augment surgical tolerance and recovery in children. These findings bolster the choice of aggressive microsurgical management of AVMs and recalibration of surgical risk assessment in children.

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Rene O. Sanchez-Mejia, Mary Limbo, Jason S. Cheng, Joaquin Camara, Mariann M. Ward and Nicholas M. Barbaro

Object

Trigeminal neuralgia (TN) is characterized by paroxysmal lancinating pain in the trigeminal nerve distribution. When TN is refractory to medical management, patients are referred for microvascular decompression (MVD), radiofrequency ablation, or radiosurgery. After the initial treatment, patients may have refractory or recurrent symptoms requiring retreatment. The purpose of this study was to determine what factors are associated with the need for retreatment and which modality is most effective.

Methods

To define this population further, the authors evaluated a cohort of patients who required retreatment for TN. The mean follow-up periods were 51 months from the first treatment and 23 months from the last one, and these were comparable among treatment groups.

Conclusions

Trigeminal neuralgia can recur after neurosurgical treatment. In this study the authors demonstrate that the number of patients requiring retreatment is not negligible. Lower retreatment rates were seen in patients who initially underwent radiosurgery, compared with those in whom MVD or radiofrequency ablation were performed. Radiosurgery was more likely to be the final treatment for recurrent TN regardless of the initial treatment. After retreatment, the majority of patients attained complete or very good pain relief. Pain relief after retreatment correlates with postoperative facial numbness.

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Rene O. Sanchez-Mejia, Steven G. Ojemann, Jeff Simko, Uzair B. Chaudhary, Jay Levy and Michael T. Lawton

✓Epithelioid angiosarcoma of bone is a rare, high-grade lesion that is highly vascular and can be associated with a bleeding diathesis. An association has been reported in angiosarcomas in other locations with coagulopathy from tumor-related disseminated intravascular coagulopathy and fibrinolysis. The authors report the case of a rare occurrence of a primary sacral epithelioid angiosarcoma associated with a large epidural hematoma and a severe bleeding diathesis.

A 25-year-old woman presented with weakness, fatigue, neck and low-back pain, and progressive left S-1 radiculopathy. Imaging studies revealed a large ventral epidural hematoma extending from the sacral region rostrally to C-2 and a vascular tumor located in the sacrum. The patient underwent a sacral laminectomy, complicated by postoperative bleeding from the wound, and required massive transfusions. Ultimately, multimodal therapy was required to obtain hemostasis, including the use of endovascular embolization, radiation therapy, and an infusion of epsilon-aminocaproic acid with heparin. This case represents the first report of a primary epithelioid angiosarcoma in the sacrum and emphasizes that the coagulopathy seen in angiosarcoma is also a feature of this epithelioid variant.

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Tae Sung Park

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Intracranial dermoid cyst mimicking hemorrhage

Case report and review of the literature

Rene O. Sanchez-Mejia, Mary Limbo, Tarik Tihan, Michael G. Galvez, Meredith V. Woodward and Nalin Gupta

✓ Intracranial dermoid cysts are rare congenital lesions that result from abnormal sequestration of ectodermal cells during neural tube formation. Dermoid cysts are typically hypodense on computed tomography, but when hyperdense may mimic a hemorrhage. The authors report the case of a 16-year-old boy who presented with a history of chronic progressive headaches. Findings on a CT scan were indicative of hemorrhage. Magnetic resonance imaging revealed the lesion to be a dermoid cyst with unusual characteristics. Upon gross resection, the lesion appeared to be a dermoid cyst without hemorrhage, but histological evaluation revealed evidence of hemorrhage. The authors describe their experience and review the literature, emphasizing that a dermoid cyst may have unusual radiographic characteristics indicative of hemorrhage and may contain areas of hemorrhage on histological examination.

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Guy Rosenthal, Rene O. Sanchez-Mejia, Nicolas Phan, J. Claude Hemphill III, Christine Martin and Geoffrey T. Manley

Object

Cerebral autoregulation may be altered after traumatic brain injury (TBI). Recent evidence suggests that patients' autoregulatory status following severe TBI may influence cerebral perfusion pressure management. The authors evaluated the utility of incorporating a recently upgraded parenchymal thermal diffusion probe for the measurement of cerebral blood flow (CBF) in the neurointensive care unit for assessing cerebral autoregulation and vasoreactivity at bedside.

Methods

The authors evaluated 20 patients with severe TBI admitted to San Francisco General Hospital who underwent advanced neuromonitoring. Patients had a parenchymal thermal diffusion probe placed for continuous bedside monitoring of local CBF (locCBF) in addition to the standard intracranial pressure and brain tissue oxygen tension (PbtO2) monitoring. The CBF probes were placed in the white matter using a separate cranial bolt. A pressure challenge, whereby mean arterial pressure (MAP) was increased by about 10 mm Hg, was performed in all patients to assess autoregulation. Cerebral CO2 vasoreactivity was assessed with a hyperventilation challenge. Local cerebral vascular resistance (locCVR) was calculated by dividing cerebral perfusion pressure by locCBF. Local cerebral vascular resistance normalized to baseline (locCVRnormalized) was also calculated for the MAP and hyperventilation challenges.

Results

In all cases, bedside measurement of locCBF using a cranial bolt in patients with severe TBI resulted in correct placement in the white matter with a low rate of complications. Mean locCBF decreased substantially with hyperventilation challenge (−7 ± 8 ml/100 g/min, p = 0.0002) and increased slightly with MAP challenge (1 ± 7 ml/100 g/min, p = 0.17). Measurements of locCBF following MAP and hyperventilation challenges can be used to calculate locCVR. In 83% of cases, locCVR increased during a hyperventilation challenge (mean change +3.5 ± 3.8 mm Hg/ml/100 g/min, p = 0.0002), indicating preserved cerebral CO2 vasoreactivity. In contrast, we observed a more variable response of locCVR to MAP challenge, with increased locCVR in only 53% of cases during a MAP challenge (mean change −0.17 ± 3.9 mm Hg/ml/100 g/min, p = 0.64) indicating that in many cases autoregulation was impaired following severe TBI.

Conclusions

Use of the Hemedex thermal diffusion probe appears to be a safe and feasible method that enables continuous monitoring of CBF at the bedside. Cerebral autoregulation and CO2 vasoreactivity can be assessed in patients with severe TBI using the CBF probe by calculating locCVR in response to MAP and hyperventilation challenges. Determining whether CVR increases or decreases with a MAP challenge (locCVRnormalized) may be a simple provocative test to determine patients' autoregulatory status following severe TBI and helping to optimize CPP management.