Neurofibromatosis Type 1: Magnetic Resonance Imaging Findings

Abstract

The purpose of this study was to determine the locations and characterize the types of brain abnormalities noted on brain magnetic resonance imaging in patients with probable and definite neurofibromatosis type 1. Patients with definite neurofibromatosis type 1 (n = 17) were studied when clinically indicated, and patients with probable neurofibromatosis type 1 (n = 9) were studied to evaluate for asymptomatic optic pathway glioma. Of the 26 patients evaluated, 14 (53%) had high-intensity signal abnormalities and 11 (42%) had significant structural abnormalities. Subsequent clinical follow-up has confirmed conversion to a definite neurofibromatosis type 1 diagnosis in three of the four cases of probable neurofibromatosis type 1 who had high-intensity signal abnormalities. The most common locations of high-intensity signal lesions were in the globus pallidus of the basal ganglia and cerebellar white matter. Tortuous or thickened optic nerves and/or optic chiasm were seen in eight cases. Brain magnetic resonance imaging scans frequently reveal high-intensity signal lesions and structural abnormalities in selected patients with both probable and definite neurofibromatosis type 1. These findings may allow for a definitive diagnosis in clinically probable cases.

Region-specific astrogliosis in brains of mice heterozygous for mutations in the neurofibromatosis type 1 (Nf1) tumor suppressor

“…In contrast to our results in Nf1/nf1 mice, human brains analyzed showed widespread astrogliosis [39]. The brain regions that show astrogliosis in this study also do not correlate with the distribution of UBOs in humans; UBOs are most frequent in the cerebellum, basal ganglia, brainstem, and subcortical white matter [2,10,12,13,51]. The lateral region of the periaqueductal gray is mainly known for relevance to pain perception and in autonomic cardiac regulation, the nucleus accumbens functions in pleasure circuitry in the limbic system, while the hippocampus is associated with learning and memory.…”

“…A second abnormality is observed in a sub-population of children with NF1, who show foci of increased T2 signal on brain magnetic resonance imaging that are not enhanced by gadolinium, visible by CT, or associated with focal neurologic deficits. These have been called unidentified bright objects (UBOs) [12,38,46], and are found primarily in the cerebellum, subcortical white matter, brainstem, and basal ganglia [2,10,12,13,51]. UBOs disappear with increasing age.…”

Screening and Diagnosis of Optic Pathway Gliomas in Children with Neurofibromatosis Type 1 by Using Sweep Visual Evoked Potentials

“…Their nature is unclear, but they occur in up to 60% of patients. 34 Nine (64.3%) of 14 patients in the nOPG group in our study had UBOs. It may be that the slight reduction in contrast sensitivity in the patients with NF-1 without OPGs in the present study is the result of UBOs.…”

Decoding the Deep Gray: A Review of the Anatomy, Function, and Imaging Patterns Affecting the Basal Ganglia

“…Because they tend to resolve with maturity, it is unlikely that they represent hamartomas or heterotopias. [28][29][30][31][32][33] The globus pallidus and pars reticulata of the substantia nigra contain the highest concentration of iron in the brain and are highly susceptible to carbon monoxide poisoning, due to the affinity of carbon monoxide for the porphyrin ring of the hemoglobin molecule. 34,35 Symmetric CT hypoattenuation and T2 hyperintensity due to necrosis in the globus pallidus are characteristic of carbon monoxide poisoning (Fig 10B).…”