A rare case of cerebellar agenesis: a probabilistic Constrained Spherical Deconvolution tractographic study

Abstract

Aim of this study is to show the potential of probabilistic tractographic techniques, based on the Constrained Spherical Deconvolution (CSD) algorithms, in recognizing white matter fiber bundle anomalies in patients with complex cerebral malformations, such as cerebellar agenesis. The morphological and tractographic study of a 17-year-old male patient affected by cerebellar agenesis was performed by using a 3Tesla MRI scanner. Genetic and neuropsychological tests were carried out. An MRI morphological study showed the absence of both cerebellar hemispheres and the flattening of the anterior side of the pons. Moreover, it showed a severe vermian hypoplasia with a minimal vermian residual. The study recognized two thin cerebellar remnants, medially in contact with the small vermian residual, at the pontine level. The third ventricle, morphologically normal, communicated with a permagna cerebello-medullary cistern. Probabilistic CSD tractography identified some abnormal and aberrant infratentorial tracts, symmetrical on both sides. In particular, the transverse pontine fibers were absent and the following tracts with aberrant trajectories have been identified: "cerebello-thalamic" tracts; "fronto-cerebellar" tracts; and ipsilateral and contralateral "spino-cerebellar" tracts. Abnormal tracts connecting the two thin cerebellar remnants have also been detected. There were no visible alterations in the main supratentorial tracts in either side. Neuropsychiatric evaluation showed moderate cognitive-motor impairment with discrete adaptive compensation. Probabilistic CSD tractography is a promising technique that overcome reconstruction biases of other diffusion tensor-based approaches and allowed us to recognize, in a patient with cerebellar agenesis, abnormal tracts and aberrant trajectories of normally existing tracts.

Improvement in White Matter Tract Reconstruction with Constrained Spherical Deconvolution and Track Density Mapping in Low Angular Resolution Data: A Pediatric Study and Literature Review

“…In the past few years, several studies have applied CSD to pediatric data acquired with different acquisition parameters. For example, Mormina et al ( 38 ) used CSD-PT to evaluate the structural organization in a 17-year-old patient with cerebellar agenesis, acquiring the images on a 3 T scanner, with 60 gradient directions and a b-value of 1,000 s/mm 2 . Besseling et al ( 39 ) investigated the correlation between functional and structural connectivity in children with rolandic epilepsy compared with healthy controls.…”

3 Tesla-Diffusion Tensor Imaging in Autosomal Dominant Polycystic Kidney Disease: The Nephrologist's Point of View

“…Although 3T-tractography has been widely employed in neurological field [18,19,20,21], this is the first study in which this method has been used to evaluate morphologic and functional features in ADPKD patients (fig. 4, 5).…”

Primary cerebellar agenesis presenting as isolated cognitive impairment

“…[ 1 4 ] To the best of our knowledge, eleven living cases of cerebellar agenesis have been reported till date. [ 1 2 3 ] The clinical presentation is highly variable. Cerebellar agenesis has been reported to be associated with profound motor impairment.…”

“…Our case is unique in that the child presented with isolated cognitive impairment with no motor impairment. [ 1 2 3 ] The clinical presentation is highly variable. Mild to profound motor impairment, mental and behavioral abnormalities have been described in these patients.…”