Michael Tenner

Open-ring imaging sign Highly specific for atypical brain demyelination

Objective: To test the specificity for demyelination of a new neuroimaging sign: contrast enhancement shaped as an open ring or a crescent circumscribed to the white matter. Background: Brain demyelination can cause ring enhancement mimicking neoplasm or infection on CT or MRI. Methods: A MEDLINE search of pathology-proved demyelination yielded 32 illustrated cases of ring-enhancing lesions published between 1981 and 1995. Controls consisted of the same number of published images of neoplasms and infections, pathology proved, and matched by year of publication, and age and gender of the patient. Two neuroradiologists read the images twice independently 1 year apart. Results: Interrater agreement was good (κ = 0.64 and 0.66 for either reading). Test-retest reliability was high (κ = 0.75 and 0.74 for either rater). The open-ring sign clearly distinguished demyelinating lesions from neoplasms and infections. For demyelination versus neoplasm or infection, the specificity of the reading by the first neuroradiologist was 93.8 (95% CI, 86 to 98), and that of the second was 84.4 (95% CI, 74 to 92). The likelihood ratio of demyelination versus neoplasm averaged 5.2, and versus infection, 17.2. That is, if the lesions had the same incidence in the population, in the presence of an open-ring sign demyelination would be five times more likely than neoplasm and 17 times more likely than infection. However, given the much higher incidence of neoplasms and infections, these lesions are still frequently responsible for open-ring enhancement. Conclusions: The open-ring sign is often present in large, contrast-enhancing demyelinating lesions and helps to differentiate them from neoplasms and infections.

Vertebral Artery Dissection in Children: A Comprehensive Review

Vertebral artery dissection (VAD) has been infrequently recognized in children. The authors have reviewed 68 reported cases of VAD in children in the existing literature. An association between routine types of neck movement in sports and the evolution of VAD was recognized in half of the reported cases. Boys outnumbered girls by a ratio of 6.6 to 1, in contrast to adults, for whom the male to female ratio is approximately equal (1.3 to 1). Neck pain, one of the hallmark symptoms of VAD in adults, was infrequently noted in this young population (12%). Most children presented with various combinations of symptoms and signs, including ataxia (53%), headache (38%) and vomiting (34%). Eye signs or symptoms were noted in 72% of patients, and paresis/paralysis of one or more extremity occurred in 54%. Angiography was the method most frequently used to diagnose VAD (63/68; 93%). Magnetic resonance angiography (MRA) revealed pathognomonic signs of VAD in only 3 out of 13 patients evaluated (23%). In this series of 68 patients, 48 reports failed to indicate whether or not a cervical X-ray was performed, but in the 20 patients for whom such information was recorded, half had skeletal abnormalities in the occipital/atlas/axis region. The most common treatments were antiplatelet therapy (n = 15) and anticoagulation with (n = 8) or without (n = 7) supplemental antiplatelet therapy. Asymptomatic recovery occurred in 12 of the 15 patients (80%) who received antiplatelet therapy compared with 4 of the 15 patients (27%) who received anticoagulation therapy with or without antiplatelet therapy. There is a very high incidence of associated cervical anomalies in children with VAD. Further studies are required to determine if noninvasive examinations such as magnetic resonance imaging, ultrasonography, computed tomography angiography and MRA could replace angiography as the modality of choice in establishing the diagnosis of VAD in children. The role of different therapies for children presenting with symptoms related to VAD is unclear.

Growing burr hole: enlarging pseudomeningocele at the site of a craniostomy.

BackgroundGrowing skull fractures and other enlarging skull defects are rare postoperative occurrences. We report here on a 10-month-old girl who presented with an enlarging burr hole and pseudomeningocele after an endoscopic third ventriculocisternostomy.MethodsEvaluation of an enlarging subcutaneous mass at the site of the burr hole included computed tomography scans and magnetic resonance imaging, which revealed a pseudomeningocele. The patient underwent repair of the lesion, including dural closure and cranioplasty.ConclusionsGrowing skull fractures or other enlarging bone defects may occur after burr hole placement, particularly in infants who require larger access sites for endoscopy.

Diagnostic challenges in Balamuthia mandrillaris infections

Balamuthia mandrillaris is an emerging cause of subacute granulomatous amebic encephalitis (GAE). The diagnosis of this infection has proven to be difficult and is usually made postmortem. Early recognition and treatment may offer some benefit. This report describes a previously healthy woman who died from GAE due to B. mandrillaris.

Traumatic arteriovenous fistula of the posterior inferior cerebellar artery treated with endovascular coil embolization: case report

BACKGROUND High-flow intracranial arteriovenous (AV) fistulas associated with giant varices are rare lesions. These varices can present with symptoms from mass effect, spontaneous hemorrhage, and seizures to cardiac failure. Direct AV fistulas of the posterior inferior cerebellar artery (PICA) are extremely rare lesions, with only two cases reported in the literature. CASE DESCRIPTION The authors present an unusual case of a 25-year-old male with a direct AV fistula of the PICA that resulted from a fracture of the occipital condyle. This high-flow AV fistula drained into a giant varix of the vein of the lateral recess that compressed the brainstem, resulting in a Wallenberg syndrome. The patient underwent embolization of the proximal PICA feeding the fistula with a Guglielmi detachable coil (GDC), which resulted in thrombosis of the varix. A postembolization angiogram showed occlusion of the PICA AV fistula and draining varix. A computed tomography (CT) scan performed at a 10-month follow-up visit showed dramatic decompression of the brainstem. Although the patient continued to have some sensory changes secondary to Wallenberg syndrome, he was otherwise doing well neurologically. CONCLUSION The treatment of this lesion is difficult because of its location near the brainstem. Postocclusion edema or hemorrhage can result in mass effect and life-threatening brainstem compression. Our patient, whose AV fistula was caused by trauma, was treated effectively with GDC embolization.

Reversal of Radiographically Impending Stroke with Multiple Intraarterial Papaverine Infusions in Severe Diffuse Cerebral Vasospasm Induced by Subarachnoid Hemorrhage

Summary.Background: Selective intraarterial infusion of papaverine is used in the treatment of symptomatic cerebral vasospasm induced by aneurysmal subarachnoid hemorrhage (SAH). Delays in instituting therapy for vasospasm can lead to irreversible cerebral infarction and a devastating outcome. Endovascular papaverine treatment of vasospasm in the presence of low-attenuation lesions on computed tomography (CT) is controversial, because of the fear of reperfusion hemorrhage in completed infarcts. Method: Two patients with aneurysmal SAH who subsequently developed severe diffuse vasospasm were identified. In both patients, large areas of low-attenuation change suggesting impending cerebral infarction were seen on CT scans. The patients received multiple infusions of intraarterial papaverine in an effort to treat vasospasm refractory to medical management. Findings: After multiple intermittent administrations of papaverine, which initially appeared to increase the low-attenuation changes, there was dramatic reversal of the radiographic findings. There was also improvement in circulation time, transcranial Doppler velocities, and clinical outcome. Interpretation: These findings suggest that in some patients, intraarterial infusions of papaverine initiated in the earliest stages of ischemia may exacerbate the radiographic appearance of low-attenuation changes, but may ultimately reverse the evolution of cerebral infarction.

Variation of the magnetic relaxation rate 1/T1 of water protons with magnetic field strength (NMRD Profile) of untreated, non-calcified, human astrocytomas: correlation with histology and solids content

SummaryThe magnetic relaxation rate 1/T1 of tissue water protons was measured over a wide range of magnetic field strengths (NMRD profile) for 92 fresh surgical specimens of astrocytomas to search for correlations of 1/T1 with tumor histology, as determined by light microscopy, and to assess the diagnostic potential of NMRD profiles for grading astrocytomas. A third goal was to elucidate the molecular determinants of 1/T1. Each specimen was histologically graded and inspected for evidence of mineral deposits (Ca, Fe); its dry weight was determined and expressed in % of original wet weight. To minimize variability not directly related to tumor grade, this initial report is limited to NMRD profiles of 47 non-calcified, non-mehorrhagic, untreated astrocytomas. For these, the mean value of 1/T1 at very low magnetic field strenghts was found to increase with increasing grade of malignancy; no clear correlation could be demonstrated at high fields where most imaging is done. The spread of 1/T1 for different grades of malignancy is large, however, and the overlap significant, even at the lowest field, so that astrocytomas can not be graded by NMRD profiles alone. Average 1/T1 and average dry weight increase with grade of malignancy; but the variability of 1/T1 among specimens of the same dry weight is large, indicating that at least one other cellular parameter, not variable in normal tissue, influences 1/T1 strongly. We hypothesize that this parameter reflects changes at the molecular level in size distribution, mobility, or intermolecular interaction of cytoplasmic proteins. Which specific changes are induced by malignant transformation in astrocytomas remains to be investigated.

Aspergillus osteomyelitis of the lumbar spine complicated with orbital apex syndrome: A potential role of the Batson's plexus in disease propagation

We report a rare case of orbital apex syndrome following epidural steroid injections of the lumbar spine in an immunocompetent individual with osteomyelitis and discitis caused by Aspergillus fumigatus. We suspect that the craniospinal venous system, also known as the Batsons plexus, was the main route for steroid-facilitated disease propagation from the spine to intracranial structures.

Determinants of signal intensity in MRI of human astrocytomas

MRI studies at 1.5 T of 38 patients with histologically confirmed astrocytomas were reviewed to search for a relationship of signal intensity with grade of malignancy, rediotherapy used for recurrent tumours and calcium deposits in surgical specimens. Signal intensity of tumours compared with normal brain was rated on a scale of 1 to 5 on T1- and T2-weighted images. Surgical specimens of each tumour were graded histopathologically on a scale of I to III and examined for calcium deposits. CT scans were searched for evidence of calcification. The majority of astrocytomas appeared hypointense on T1-weighted and hyperintense on T2-weighted images. Of 18 tumours with increased signal on T1-weighted images, grade II were prevalent, followed by calcified astrocytomas. Among 14 tumours with decreased signal on T2-weighted images the order was similar, but the ratio of high-grade to low-grade tumours did not differ in relation to signal intensity, while on T1-weighted images the ratio was higher in the group with increased signal intensity. A high grade of malignancy and microcalcifications were associated with an increased signal intensity of astrocytomas on T1-weighted sequences without contrast agent. The above factors did not influence significantly the signal intensity on T2-weighted images.

A Novel Approach Using Electromagnetic Neuronavigation and a Flexible Neuroendoscope for Placement of Ommaya Reservoirs.

OBJECTIVE Placement of intraventricular catheters in oncology patients can be associated with morbidity given their small to slit-like ventricles and underlying hematologic disorders. We studied the accuracy of placing Ommaya reservoirs using neuronavigation and a flexible neuroendoscope to verify catheter positioning. METHODS Ommaya reservoirs placed in 25 oncology patients between 2013 and 2015 were retrospectively reviewed. Twenty-five ventricular catheters were placed using the AxiEM stealth frameless neuronavigation system and a flexible neuroendoscope. Postoperative catheter accuracy, operative complications, and postoperative complications were assessed. We discuss surgical protocol and technical nuances. RESULTS All ventricular catheters were successfully placed into the ipsilateral (84%) or contralateral (16%) foramen of Monro. A single ventricular catheter pass was needed to cannulate the ventricle in 96% of patients. The mean accuracy was 4.09 ± 3.47 mm from the target, the ipsilateral foramen of Monro. One patient had a catheter tract hemorrhage seen on postoperative imaging related to thrombocytopenia. No postoperative neurologic deficits were seen. CONCLUSIONS A combined neuronavigation and neuroendoscopic approach improved catheter tip accuracy compared with accuracy rates described in the literature using other techniques. This approach can be adapted toward routine clinical practice of placing ventricular shunt catheters and Ommaya reservoirs.