Stephen T. Hecht

Longitudinal MRI findings in pyridoxine-dependent seizures

Background: Pyridoxine dependency is an uncommon familial cause of intractable seizures in newborns and infants. Fewer than 100 patients have been reported, and only four reports have included examples of brain imaging findings. We report the first longitudinal MRI findings in two patients with this condition. Methods: Six brain MR scans, three each from two patients with pyridoxine-dependent seizures, were reviewed. Morphometry of selected axial images was performed to calculate the ventricle-to-brain ratio (VBR). Patients: A girl, followed for 5 years, presented with intrauterine fetal seizures and neonatal seizures, and pyridoxine dependency was confirmed at 3.5 months of age. This patient had a subsequent history of poor compliance with pyridoxine therapy and severe developmental disability. A boy, followed for 9 years, presented with neonatal seizures, and pyridoxine dependency was diagnosed at 8 months of age. Results: The serial MR scans demonstrated progressive dilation of the ventricular system and atrophy of the cortex and subcortical white matter together with an increase in the VBR. These progressive abnormalities were greater in the 5-year-old girl. Conclusion: Pyridoxine-dependent seizures are due to an inborn abnormality in the pyridoxine-dependent synthesis of γ-aminobutyric acid (GABA). The progressive MR changes may be due to chronic excitotoxicity caused by an imbalance of cerebral levels of GABA and glutamic acid.

Multiple intracranial and systemic aneurysms associated with infantile-onset arterial fibromuscular dysplasia

Fibromuscular dysplasia (FMD) is usually an adult onset, segmental, nonarteriosclerotic, and noninflammatory vasculopathy involving predominantly systemic medium and small arteries. The renal and extracranial portion of the internal carotid arteries are most commonly affected, followed by visceral and other systemic arteries. According to collective experience, renovascular disease occurs in 60 to 75% of patients with FMD, cerebrovascular disease in 25 to 30%, and multivessel involvement in up to 24%.1 We report a patient with infantile-onset, biopsy-proven renal and mesenteric FMD, who at age 23 years presented with sudden blindness caused by ophthalmic artery occlusion from FMD and visceral hemorrhages caused by ruptured FMD aneurysms. Case report. Current episode. The patient, a 23-year-old right-handed man with hypertension, was hospitalized for sudden blindness and retroorbital pressure of the right eye, both preceded 3 weeks earlier by tunnel vision of the right eye. On admission, pulse rate was 76 beats per minute and blood pressure 111/87 mm Hg. Multiple, small pulsating protrusions of the scalp were evident. Neurologic examination revealed poor light perception in the right eye, a right afferent pupillary defect, and pallor of the right fundus with swollen optic disc and collapsed peripheral arterioles. Results of funduscopic examination of the left eye were normal. Treatment with acetazolamide, oxygen, and timolol maleate eye drops improved light perception. Admission laboratory …

Phase III clinical trial comparing iodixanol and iohexol in cerebral angiography

RATIONALE AND OBJECTIVES We report on our early clinical experience in the United States with the nonionic dimeric (6:1 ratio) contrast medium iodixanol in cerebral angiography. Iodixanol has an osmolality less than half that of monomeric, nonionic contrast media such as iohexol at equivalent iodine concentrations and is isosmotic to blood. METHODS Forty-nine adult patients undergoing elective cerebral angiography were studied in a phase III, double-blind, randomized, parallel-design clinical trial comparing the safety and diagnostic efficacy of iodixanol at 320 mg I/ml (IOD-320) and iohexol 300 mg I/ml (IOH-300). Diagnostically adequate cerebral angiograms were routinely obtained with both contrast agents. RESULTS A total of 37% of the patients experienced adverse events (48% in the IOD-320 group and 25% in the IOH-300 group). No statistically significant differences were noted between the two groups studied in the proportion of patients with one or more adverse events or in the intensity of the adverse events. The most common adverse event was headache. There were no deaths or serious complications related to either contrast medium in this study. CONCLUSION The results of this phase III trial support the conclusion that iodixanol at a concentration of 320 mg I/ml is comparable to iohexol at 300 mg I/ml in terms of efficacy (overall radiographic diagnostic visualization) and safety.

Spinal arteriovenous malformation presenting as meningitis.

An 8‐month‐old boy presented with a two‐day history of lethargy. Meningitis was suspected, and cerebrospinal fluid examination demonstrated pleocytosis and elevated protein. After initial improvement with antibiotic and steroid therapy, progressive lower extremity weakness developed, and a midthoracic spinal cord arteriovenous malformation (AVM) was diagnosed. These lesions present rarely in infancy; the classification and pathophysiology of spinal cord AVMs are reviewed.

Angiographic film substraction using a laser digitizer and computer processing

Digital subtraction angiography has been accepted as an invaluable clinical tool over the past decade; however, film-screen-based angiography is still performed routinely when high-resolution or large field-of-view angiograms are needed. A technique is presented whereby two films from an angiographic sequence are digitized using a high-resolution laser digitizer, and the digitized images are aligned, subtracted, and displayed using the computer. To accommodate for some types of patient motion, an image warping algorithm is presented and discussed in detail. The warping algorithm is piecewise linear, using triangular regions for warping, resulting in a global nonlinear transform across triangle elements. An algorithm describing optimal triangle selection also is discussed. The results show that subtraction images of excellent quality can be produced by the proposed technique, and suggest that, in some settings, digitized subtraction films may be preferred over conventional film subtraction.

Palliative embolization of fibrosarcoma for control of tumor-induced hypoglycemia

A 77-year-old woman with prior long-standing insulin-dependent diabetes presented with malignant hypoglycemia secondary to insulin-like substances excreted from a large unresectable fibrosarcoma of the left thigh. Partial embolization of the tumor supply from the deep femoral artery was performed using 150–250 μm polyvinyl alcohol foam particles. After embolization, the patients serum glucose levels reverted to normal and she could be discharged from the hospital.