Jon I. McIver
Mayo Clinic
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Featured researches published by Jon I. McIver.
Journal of Neuro-oncology | 2004
Jon I. McIver; Bruce E. Pollock
Radiation-induced neoplasms are extremely rare after stereotactic radiosurgery. To date, only 3 cases meet Cahans criteria in the world literature. We present a fourth case of a radiation-induced neoplasm arising after radiosurgery.The patient is a 43-year-old woman who presented with a right cerebellar anaplastic astrocytoma 64 months after radiosurgery for metastatic melanoma. Initially, 3 brain metastases involving the inferior right temporal (2 tumors) and right frontal regions were treated. Following radiosurgery, the patient underwent whole brain radiotherapy (37.5 Gy). Twenty-two months later, a second radiosurgical procedure was performed for a recurrent right temporal lobe metastasis. The area of cerebellum where the glioma developed received a maximum dose of 7.7 and 1.5 Gy during the 2 procedures, respectively. Support that radiosurgery contributed to the development of this glioma are the tumors location and the rarity of adult cerebellar astrocytomas.The risk of radiation-induced tumors after radiosurgery is unknown. To better define the incidence of radiation-induced neoplasms after radiosurgery, all potential cases should be presented and discussed in an open, candid fashion.
Neurosurgery | 2005
L. Gerard Toussaint; Jonathan A. Friedman; Eelco F. M. Wijdicks; David G. Piepgras; Mark A. Pichelmann; Jon I. McIver; Robyn L. McClelland; Douglas A. Nichols; Fredric B. Meyer; John L. D. Atkinson
OBJECTIVE:Survival of cardiac arrest (CA) after aneurysmal subarachnoid hemorrhage (SAH) is poorly characterized. We analyzed the clinical course and outcome of patients who survived resuscitation for CA after aneurysmal SAH. METHODS:Medical records of all patients with acute SAH treated at Mayo Clinic between 1990 and 1997 were reviewed. Three hundred five consecutive patients with angiographically proven aneurysmal SAH presenting within 7 days of ictus were analyzed. CA was defined as a pulseless state, documented by medical personnel, for which resuscitation was performed. Outcome was measured with the Glasgow Outcome Scale score at longest follow-up (mean, 16 mo). RESULTS:Data from 11 patients (3.6%) who had 14 episodes of CA were analyzed. Six patients had CA before reaching the hospital and were successfully resuscitated. Nine of 14 CA episodes occurred at hemorrhage or rehemorrhage. No patient with in-hospital CA failed to be resuscitated. Overall mortality in patients who had CA (46%) was higher than that of patients without CA (15%; P = 0.019). Outcome for all patients who had CA (mean Glasgow Outcome Scale score, 2.5) was worse than for patients without CA (mean Glasgow Outcome Scale score, 3.9; P = 0.005). However, half of the survivors of CA after SAH were living independently with limited deficit at longest follow-up. CONCLUSION:Most cases of CA occur at the time of initial or recurrent SAH. Resuscitation for in-hospital CA is likely to be successful. Although CA after aneurysmal SAH is associated with significantly higher mortality, the outcome of survivors of CA is not worse than that for other patients after aneurysmal SAH.
Neurosurgery | 2001
Jon I. McIver; Bernd W. Scheithauer; Charlotte H. Rydberg; John L. D. Atkinson
OBJECTIVE AND IMPORTANCE A case of acutely symptomatic epidural hematoma caused by metastatic hepatocellular carcinoma (HCC) to the cranium is reported. This is a rare case of metastatic HCC without known primary presenting as an epidural hematoma. CLINICAL PRESENTATION The patient presented with an acute onset of headache, aphasia, and right hemiparesis 2 weeks after he experienced minor trauma to the cranium. An emergency computed tomographic scan of the head revealed the presence of a left parietal epidural hematoma. INTERVENTIONAn emergency evacuation of the epidural hematoma was performed, and metastatic HCC was diagnosed. CONCLUSIONThe patient’s neurological deficits were reversed with surgical intervention, and he is now undergoing palliative chemotherapy. This was the first clinical manifestation of HCC in this patient. This case reaffirms the neurosurgeon’s role in the complex, multidisciplinary care of patients with craniospinal metastasis.
Neurocritical Care | 2004
Frederic P. Collignon; Jonathan A. Friedman; David G. Piepgras; Mark A. Pichelmann; Jon I. McIver; L. Gerard ToussaintIII; Robyn L. McClelland
Introduction: Recent evidence suggests that magnesium may be neuroprotective in the setting of cerebral ischemia, and therapeutic magnesium infusion has been proposed for prophylaxis and treatment of delayed ischemic neurological deficit (DIND) resulting from vasospasm in patients with aneurysmal subarachnoid hemorrhage (SAH). We studied the association between serum magnesium levels, the development of DIND, and the outcomes of patients with SAH.Methods: We studied 128 consecutive patients with aneurysmal SAH treated at our institution between 1990 and 1997 who had a serum magnesium level measured at least once during the acute phase of their hospitalization. Delayed ischemic neurological deficit was defined as severe (major focal deficit or coma), moderate (incomplete focal deficit or decreased sensorium without coma), or none.Results: There was no significant difference in mean, minimum, or maximum serum magnesium levels between patients with and without DIND (1.93, 1.83, 2.02 versus 1.91, 1.84, 1.97 mg/dL, respectively). Similarly, no difference was found in mean serum magnesium levels among patients with severe (1.94 mg/dL), moderate (1.92 mg/dL), or no DIND (1.91 mg/dL). Analyses of serum magnesium levels before (0–4 days following SAH), during (4–14 days following SAH), and after (greater than 14 days following SAH) the period of highest risk for vasospasm revealed no association with the development or severity of DIND. Permanent deficit or death resulting from vasospasm and Glasgow Outcome Scale score at longest follow-up were similarly unaffected by serum magnesium levels overall or during any time interval. Forty (31.5%) patients were hypomagnesemic (less than 1.7 mg/dL) during hospitalization, but no difference in outcome (p=0.185) or development of DIND (p=0.785) was found when compared to patients with normal (1.7–2.1 mg/dL) or high (greater than 2.1 mg/dL) magnesium serum levels.Conclusion: We identified no relationship between serum magnesium levels and the development of DIND or outcome following aneurysmal SAH. Based on these data, magnesium supplementation to normal or high-normal physiological ranges seems unlikely to be beneficial for DIND resulting from vasospasm. However, no inference can be made regarding the value of therapeutic infusion of magnesium to supraphysiological levels.
Neurosurgery | 2005
Jon I. McIver; Bernd W. Scheithauer; John L. D. Atkinson
OBJECTIVE AND IMPORTANCE:A case of chordoid meningioma originating in the right sylvian fissure is reported. Chordoid meningiomas are uncommon tumors. This is the first reported case of a chordoid meningioma without dural attachment arising in the sylvian fissure. CLINICAL PRESENTATION:The patient presented with a generalized seizure. A heterogeneously enhancing right frontotemporal mass was identified on magnetic resonance imaging of the brain. INTERVENTION:The patient underwent a failed stereotactic biopsy attempt elsewhere. The tumor was ultimately resected using standard microsurgical techniques. CONCLUSION:Meningiomas originate from arachnoid cap cells and can arise at locations remote from the pachymeninges. Although rare, meningiomas should be included on the differential diagnosis of sylvian fissure lesions.
Surgical Neurology | 2003
Jon I. McIver; Michael J. Link; Caterina Giannini; Aaron Cohen-Gadol; Colin L. W. Driscoll
OBJECTIVE We report an unusual case of an extraventricular choroid plexus papilloma (CPP) occupying the right ventral foramen magnum and lower right cerebellopontine angle (CPA), occurring together with a petro-tentorial meningioma. The clinical presentation, preoperative imaging, differential diagnosis, surgical treatment and histologic features of the two tumors are discussed. CASE DESCRIPTION The patient presented with a 2-month history of headache, altered facial sensation, dysphagia, and gait unsteadiness. Neurologic examination confirmed a wide-based, unsteady gait, hoarse voice, anisocoria, and partial right vocal cord paralysis. Diagnostic imaging demonstrated right petro-tentorial and right ventral foramen magnum lesions, both hyperintense on contrasted images and suggestive of meningiomas. A right suboccipital craniotomy and far lateral approach was used to resect both tumors. The petro-tentorial tumor was a histologically confirmed meningioma, but the ventral foramen magnum tumor was an extraventricular CPP. CONCLUSIONS This is a rare occurrence of concomitant meningioma and CPP. There is no known link between these two tumors. An exophytic 4th ventricular CPP must be considered in the differential diagnosis of a CPA or foramen magnum tumor.
Neurosurgery | 2003
Jonathan A. Friedman; Jon I. McIver; Frederic P. Collignon; Douglas A. Nichols; David G. Piepgras
OBJECTIVE AND IMPORTANCECyst formation within the brain parenchyma after endovascular coil occlusion of an intracranial aneurysm is a previously undescribed occurrence. We describe a 70-year-old woman who presented with a symptomatic pontine cyst 1 year after uncomplicated stenting and Guglielmi detachable coil occlusion of an unruptured basilar artery trunk aneurysm. CLINICAL PRESENTATIONA 70-year-old woman presented with an episode of transient dysequilibrium and gait difficulty. Magnetic resonance imaging and cerebral angiography demonstrated a 15-mm distal basilar artery trunk aneurysm. Endovascular stenting and coil occlusion of the aneurysm were performed without technical complications. One year after the initial treatment, the patient developed progressive dysarthria, dysphagia, diplopia, and left hemiparesis. A large pontomesencephalic cyst adjacent to the coiled basilar aneurysm was identified on magnetic resonance imaging scans. INTERVENTIONA subtemporal craniotomy and decompression of the pontomesencephalic cyst were performed. The patient’s symptoms of brainstem dysfunction improved temporarily but recurred within 2 months, necessitating reoperation for cyst drainage and placement of a cyst-peritoneal shunt. CONCLUSIONIntra-axial cyst formation after stenting and endovascular occlusion of an intracranial aneurysm is an unusual occurrence and should be considered in the differential diagnosis of new neurological deficits after endovascular treatment. The pathophysiological mechanism of cyst formation in this case is not known.
Rivista Di Neuroradiologia | 2003
Jonathan A. Friedman; Douglas A. Nichols; Fredric B. Meyer; Mark A. Pichelmann; Jon I. McIver; L. G. Toussaint; P. L. Axley; Robert D. Brown
We reviewed the medical records and angiographic films of 83 consecutive patients treated with endovascular GDC occlusion for a saccular cerebral aneurysm following SAH from 1991-2000 (figure 1). The treated aneurysm was felt to be the source of SAH in every case. All procedures were performed at a single institution, by a single endovascular surgeon. Patients with aneurysms arising as a result of trauma or dissection were not considered, nor were patients with mycotic or fusiform aneurysms. Only patients in whom one or more GDCs were actually detached were considered. Patients who underwent GDC occlusion of aneurysms following an incomplete previous surgical clipping or incomplete previous GDC occlusion elsewhere were excluded. In 21 patients with multiple aneurysms, only the aneurysm thought Introduction
Journal of Neurosurgery | 2003
Alejandro A. Rabinstein; Mark A. Pichelmann; Jonathan A. Friedman; David G. Piepgras; Douglas A. Nichols; Jon I. McIver; L. Gerard Toussaint; Robyn L. McClelland; Jimmy R. Fulgham; Fredric B. Meyer; John L. D. Atkinson; Eelco F. M. Wijdicks
American Journal of Neuroradiology | 2003
Jonathan A. Friedman; Douglas A. Nichols; Fredric B. Meyer; Mark A. Pichelmann; Jon I. McIver; L. Gerard Toussaint; Patsy L. Axley; Robert D. Brown