The dentato–rubro–olivary pathway revisited: New MR imaging observations regarding hypertrophic olivary degeneration

Abstract

Hypertrophic olivary degeneration (HOD) following a lesion of the dentato-rubro-olivary pathway (DROP) is a well-known imaging finding and has extensively been described in the recent literature. We reviewed our patients with HOD as a result of a lesion of the DROP in order to analyze the disruption of the DROP and the resulting HOD in comparison with the literature. We observed unusual imaging findings in four patients. In two patients it concerned new observations related to the timing and imaging appearances of HOD. HOD became only visible 6 years after a lesion in the red nucleus in one patient and a cystic degeneration of the olivary nucleus was seen 3 years after the HOD in a second patient. In two patients we found HOD that could only be explained by the existence of an afferent feedback loop between the dentate nucleus and the inferior olivary nucleus and by the knowledge that these fibers run through the ipsilateral olivary nucleus before ending in the contralateral olivary nucleus. In one of these patients the lesion was located in the inferior cerebellar peduncle. In the other patient the lesion was located on the midline in the medulla oblongata. The imaging findings in these patients reveal new observations in the stages of imaging appearances in HOD and shed light on the forgotten dentato-olivary afferent feedback loop of the DROP. Clin. Anat. 30:543-549, 2017. © 2017 Wiley Periodicals, Inc.

Differential involvement of rubral branches in chronic capsular and pontine stroke

“…The impairment of the DRT found in the present study can explain the early reports of reduced GMV in the cerebellum (Jiang et al., 2017) and disrupted contralesional cerebrocerebellar connectivity in pontine stroke (Lu et al., 2011). The DRT and the RST are the important anatomical components of the Guillain-Mollaret Triangle (GMT), which forms a feedback loop connected to the brain stem and cerebellum to control the motor activity of the spinal cord (Smets et al., 2017) .Thus, the impairment of RST would cause a secondary degeneration of the DRT. In addition, supratentorial brain damage could induce a reduction in metabolic activity and blood flow of the contralesional cerebellum (named crossed cerebellar diaschisis) (Baron et al., 1981), which can also induce rupture of the corticopontocerebellar tract (Feeney and Baron, 1986; Kim et al., 1997; Tien and Ashdown, 1992).…”

Increased intrinsic membrane excitability is associated with hypertrophic olivary degeneration in spinocerebellar ataxia type 1

“…Interestingly, however, the IO is one of the few brain regions in which degenerative hypertrophy has been previously described. This phenomenon, known as hypertrophic olivary degeneration (HOD), can occur if brainstem injury (usually pontine hemorrhage (Smets et al, 2017)) causes substantive loss of inhibitory input to the IO (Wang et al, 2019). The degenerative hypertrophy identified here appears strikingly similar to this well-described pathology, suggesting that SCA1-associated IO dysfunction may constitute a novel cause of HOD.…”

“…In addition, IO neurons are vulnerable to a pathology known as hypertrophic olivary degeneration (HOD). Clinically, HOD occurs secondary to lesions in the brainstem (pontine hemorrhage, most commonly (Smets et al, 2017)) that disrupt inhibitory fibers that travel from the contralateral dentate nucleus of the cerebellum and through the brainstem to synapse onto the IO (a white matter tract known as the Guillain-Mollaret triangle (Ogut et al, 2023)). An acute lesion to these fibers results in an initial increase in IO neuron soma size, generally observed as an increase in gross IO volume (Jellinger, 1973; Ruigrok et al, 1990; Wang et al, 2019).…”

Temporal Evolution of Hypertrophic Olivary Degeneration in a Pediatric Patient: A Case Report and Review of Literature

“…The GMT serves as a connection between the brainstem and the cerebellum and its primary function is modulation of spinal cord motor activity [ 1 , 2 ]. Interruption of the GMT can sometimes result in hypertrophic olivary degeneration (HOD), a rare type of transsynaptic degeneration [ 3 ]. HOD was initially described in a post-mortem examination by Oppenheim in 1887 [ 4 ] and more extensively studies by Guillain and Mollaret, who described its association to the dentato-rubro-olivary tract in 1931 [ 5 ].…”