Radiological Significance of Symmetric Central Tegmental Tract Hyperintensity in Pediatric Patients

Background: The central tegmental tract (CTT) is an extrapyramidal tract between the red nucleus and the inferior olivary nucleus which is part of the Guillain-Mollaret triangle (dentato-rubro-olivary system). Symmetric central tegmental tract hyperintensity (CTTH) is a pediatric brain magnetic resonance imaging (MRI) finding with an unclear clinical and radiological significance. Objectives: The aim of this retrospective study is to determine the radiological significance of CTTH on magnetic resonance imaging (MRI) in children. Patients and Methods: Pediatric patient’s MRI from January 2015 to January 2017 were retrospectively reviewed in this case series study. Patient records with presence of CTTH in their MRI were evaluated. Results: There were 39 out of 2981 brain MRIs with CTTH with a prevalence of 1.3%. Some CTTH lesions disappeared on follow-up. In two patients, the disappearance of CTTH temporally corresponded to clinical improvement. Also we had patients with hemolytic uremic syndrome, autoimmune hemolytic anemia, Wilson’s disease, combined immunodeficiency, Bartter syndrome, and autism. Conclusion: CTTH could be caused by a physiological maturation process or a physiological response of the cells in the central tegmental tract to a more widespread toxic/metabolic or ischemic insult in the brain. CTTH also appears to have a transient nature in some cases. Further research elucidating the pathophysiology of CTTH is needed.

Transaxonal degenerations of cerebellar connections: the value of anatomical knowledge

ABSTRACT Transaxonal degenerations result from neuronal death or the interruption of synaptic connections among neuronal structures. These degenerations are not common but may be recognized by conventional magnetic resonance imaging. Objective: The learning objectives of this review include recognition of the imaging characteristics of transaxonal degenerations involving cerebellar connections, the identification of potential encephalic lesions that can lead to these degenerations and correlation of the clinical manifestations with imaging findings that reflect this involvement. Methods: In this report, we review the neuroanatomical knowledge that provides a basis for identifying potential lesions that can result in these degenerations involving cerebellar structures. Results: Hypertrophic olivary degeneration results from an injury that interrupts any of the components of the Guillain-Mollaret triangle. In this work, we describe cases of lesions in the dentate nucleus and central tegmental tract. The crossed cerebellar diaschisis presents specific imaging findings and clinical correlations associated with its acute and chronic phases. The Wallerian degeneration of the middle cerebellar peduncle is illustrated by fiber injury of the pontine cerebellar tracts. A T2-hyperintensity in the dentate nucleus due to a thalamic acute lesion (in ventral lateral nuclei) is also described. Each condition described here is documented by MRI images and is accompanied by teaching points and an anatomical review of the pathways involved. Conclusion: Neurologists and radiologists need to become familiar with the diagnosis of these conditions since their presentations are peculiar and often subtle, and can easily be misdiagnosed as ischemic events, degenerative disease, demyelinating disease or even tumors.

Diffusion Tensor Imaging in a Case of Pontine Bleeding Showing Hypertrophic Olivary Degeneration and Cerebellar Ataxia

We present diffusion tensor tractography (DTT) findings in a case of hypertrophic olivary degeneration (HOD) and cerebellar ataxia. A 56-year-old man presented with abnormal ataxic gait and dysarthria. MRI 5 months after onset showed chronic pontine hematoma and enlarged bilateral inferior olivary nuclei. DTT showed decreased volume of the bilateral central tegmental tract, in accordance with the conventional hypothesis that HOD is associated with neurologic insult to the Guillain-Mollaret triangle. The patient’s cerebellar ataxia was speculated to be due to decreased decussating fibers of the superior cerebellar peduncle, and this was confirmed by DTT.

Symmetrical Central Tegmental Tract Hyperintensity on T2-weighted Images in Pediatrics: A Systematic Review

Purpose: The aim of the present study is to provide a systematic literature review of the current evidence about the Central Tegmental Tract Hyperintensity (CTTH).Methods: The literature search was performed on December 2017 using Medline PubMed, Google Scholar and Cochrane Central databases. Statistical analysis was performed using Kolmogorov-Smirnov, chi-square and the Mann-Whitney U tests.Results: Twenty publications were included. Of these, 11 were retrospective studies and 9 were case reports. In total, CTTH was reported in 226 cases. The age parameter showed a significantly non-Gaussian distribution (KS test; p-value < 0.001). The median age was 1,83 years (range: 7 days – 21 years; P25 = 1.00 year, P75 = 3.00 years; IQR = 2 years). The two most common clinical conditions associated to CTTH were cerebral palsy (51 cases; 22.6%) and glutaric aciduria type 1 (50 cases; 22.10%). CTTH was often found in the absence of other concomitant brain MRI abnormalities (32 cases; 21.8%).Conclusions: CTTH is an uncommon neuroimaging finding that is mainly related to the acquisition\improvement of a physiologicalmotor developmental process. The finding is influenced by hypoxic ischemic and toxic?metabolic factors. Data regarding DWI and follow-up are largely unreported and deserve to be further explored.

Neuroimaging in Neonatal Nonketotic Hyperglycinemia

Nonketotic hyperglycinemia is a fatal disorder of glycine metabolism presenting with intractable epilepsy, hypotonia, and developmental delay in infancy. Diagnostic tests,such as cerebrospinal fluid glycine estimation and genetic diagnostic methods, are not widely available in developing countries and hence many cases are missed or wrongly diagnosed. The magnetic resonance imaging features, such as abnormal signal intensity in the dorsal pons, midbrain, central tegmental tract, cerebral peduncle, and posterior limb of the internal capsule indicate an important clue to the possibility of the disease and help in guiding the treating neonatologist.

Bilateral surgical damage of the central tegmental tract resulting in bilateral hypertrophic olivary degeneration: An MRI case report

Hypertrophic olivary degeneration (HOD) is a rare trans-synaptic neuronal degeneration of the inferior olivary nucleus caused by an injury to the dentato-rubro-olivary connection, also known as Guillain-Mollaret triangle. It leads to hypertrophy of the affected nucleus rather than atrophy and is characterized by hyperintensity on T2-weighted images. Unilateral and bilateral cases are described. We present a case of a 70-year-old patient affected by a tumor inside the fourth ventricle who suffered from diplopia and right seventh cranial nerve palsy. He underwent surgery and developed left seventh cranial nerve palsy. Three months after resection, magnetic resonance imaging revealed the appearance of bilateral HOD. This is the first report of bilateral HOD occurrence after surgical bilateral damage of the rubro-olivary fibers running in central tegmental tracts.