The learning objective of this educational exhibit is review the anatomy of the dentate-rubro-olivary (DRO) pathway and discuss the relationship of lesions found in this pathway with the presence of hypertrophic olivary degeneration (HOD).
We will present various cases of HOD from our institution,
discuss the findings,
and review the appropriate differential diagnoses.
Hypertrophic olivary degeneration is a transynaptic degeneration that occurs as a result of a lesion which damages the neuronal fibers of the dentate-rubro-olivary (DRO) pathway.
The DRO pathway is formed by the red nucleus,
the ipsilateral inferior olivary nucleus,
the contralateral dentate nucleus and the neuronal fibers connecting these nuclei.
A triangular relationship between these three structures was originally described by French physicians Georges Guillain and Pierre Mollaret in 1931 and is therefore also known as the triangle of Guillain and Mollaret .
Findings and procedure details
There are two triangles in each posterior fossa.
The superior vertex of the triangle is formed by the red nucleus in the midbrain,
the inferior vertex is formed by the ipsilateral inferior olivary nucleus in the medulla,
and the middle vertex is formed by the contralateral dentate nucleus in the cerebellum.
(Fig. 1 and Fig. 2)
These three nuclei are connected by a set of afferent and efferent pathways (Fig. 3); the dentate-rubro pathway (afferent),
the rubro-olivary pathway (afferent),
and theindirectolivo-cerebellar pathway (efferent).
Knowledge and familiarity with the anatomy of nuclei and pathways that make up the DRO pathway facilitates evaluation of patients with HOD.
The distinction between left,
right and bilateral HOD serves as a clue to the location of the primary lesion.
Modern magnetic resonance imaging demonstrates some of the chronological changes associated with HODand may help establish the timing of primary lesions.
Link Diagnóstico Digital.
The Dentato-olivary PathwaySomatotopic Relationship Between the Dentate Nucleus and the Contralateral Inferior Olive.
Arch Neurol. 1970;22(2):135-143.doi:10.1001/archneur.1970.00480200041004
Mamdouh Hassan H.
MRI and neurological presentation of hypertrophic olivary degeneration.
Jampana R The Guillain–Mollaret triangle in action Practical Neurology 2016;16:243-246.
Olivary enlargement: Chronological and morphometric analyses.
Brin M.Consensus statement of the Movement Disorders Society on Tremor Ad Hoc Scientific committee.Mov...