Hypertrophic olivary degeneration
- Biogen Australia Pty Ltd, Investigator-Initiated Research Grant for CAD software in multiple sclerosis: finished Oct 2021 (past)
Updates to Article Attributes
Hypertrophic olivary degeneration (HOD) is a rare condition characterised by a unique pattern of trans-synaptic degeneration. It Typically it is caused by a lesion in the brainstem/cerebellum interrupting the triangle of Guillain and Mollaret, resulting in hypertrophy of the inferior olivary nucleus. The three corners
It should be noted, however, that in a significant proportion of the triangle are:patients no causative lesion will be identified 5.
red nucleusinferior olivary nucleus-
contralateraldentate nucleus
Clinical presentation
Oculopalatal tremor is a distinctive part of the presentation of hypertrophic olivary degeneration, although is also seen in many other brainstem and cerebellar conditions 4. Oculopalatal tremor comprises ocular, palatal and other muscular involuntary movements.
palatal myoclonus, rhythmic involuntary movement of the soft palate, uvula, pharynx, larynx and upper extremity are classically described clinical features
palatal myoclonus may not always be present, but when it is present, it is pathognomonic
oscillopsia may be present due to the pendular nystagmus caused by the ocular tremor 4
Pathology
The connection between the red nucleus, ipsilateral inferior olivary nucleus and the contralateral dentate nucleus forms the triangle of Guillain and Mollaret. Interruption of either connection between the dentate nucleus and contralateral red nucleus (dentatorubral tract, superior cerebellar peduncle) or the connection between the red nucleus and ipsilateral inferior olivary nucleus (central tegmental tract) leads to changes in the olive. The olive receives inhibitory (GABAergic) signals within the dentato-rubro-olivary pathway, with transneuronal degeneration causing enlargement rather than atrophy.
Pathologically, this is characterised by "trans-synaptic degeneration resulting in vacuolation of the neurones" and an increase in astrocytes. Isolated lesions of the inferior cerebellar peduncle do not cause hypertrophic olivary degeneration, as anatomically there are no direct connections between the inferior olivary nucleus and the contralateral dentate nucleus (fibres from the inferior olivary nucleus project to the cerebellar cortex via the olivocerebellar tracts and then to the dentate nucleus).
Oculopalatal tremor results from disinhibition of the inferior olivary nucleus, following the pathology in dentato-rubro-olivary pathway which is further modulated by the cerebellum 4.
Radiographic features
ItHypertrophic olivary degeneration is often seen several months after the original insult.
MRI
The inferior olivary nucleus gets larger and increases in signal intensity on T2 weighted and T2-FLAIR sequences.
Typically, within a few months, T2 signal increases and lasts for 3-4 years, whereas hypertrophy occurs later (at about one year), and resolves by 3-4 years. There are three stages:
T2 hyperintense without olivary swelling
T2 hyperintense and olivary swelling occur concomitantly, developing after 6 months and persisting for nearly 3-4 years
olivary swelling subsides, but T2 hyperintensity persists
Differential diagnosis
General imaging differential considerations include:
infarction
metastases
lymphoma
infection, including tuberculosis
-<p><strong>Hypertrophic olivary degeneration (HOD)</strong> is a rare condition characterised by a unique pattern of trans-synaptic degeneration. It is caused by a lesion in the <a href="/articles/triangle-of-guillain-and-mollaret">triangle of Guillain and Mollaret</a>, resulting in hypertrophy of the <a href="/articles/inferior-olivary-nucleus">inferior olivary nucleus</a>. The three corners of the triangle are:</p><ul>-<li><a href="/articles/red-nucleus">red nucleus</a></li>-<li>-<a href="/articles/inferior-olivary-nucleus">inferior olivary nucleus</a> </li>-<li>contralateral <a href="/articles/dentate-nucleus">dentate nucleus</a>-</li>-</ul><h4>Clinical presentation</h4><p>Oculopalatal tremor is a distinctive part of the presentation of hypertrophic olivary degeneration, although is also seen in many other brainstem and cerebellar conditions <sup>4</sup>. Oculopalatal tremor comprises ocular, palatal and other muscular involuntary movements.</p><ul>-<li>palatal myoclonus, rhythmic involuntary movement of the soft palate, uvula, pharynx, larynx and upper extremity are classically described clinical features</li>-<li>palatal myoclonus may not always be present, but when it is present, it is <a title="Pathognomonic" href="/articles/pathognomonic">pathognomonic</a>-</li>-<li>-<a title="Oscillopsia" href="/articles/oscillopsia">oscillopsia</a> may be present due to the pendular nystagmus caused by the ocular tremor <sup>4</sup>-</li>-</ul><h4>Pathology</h4><p>The connection between the red nucleus, ipsilateral inferior olivary nucleus and the contralateral dentate nucleus forms the triangle of Guillain and Mollaret. Interruption of either connection between the dentate nucleus and contralateral red nucleus (<a href="/articles/dentatorubral-tract">dentatorubral tract</a>, <a href="/articles/superior-cerebellar-peduncle-1">superior cerebellar peduncle</a>) or the connection between the red nucleus and ipsilateral inferior olivary nucleus (central <a href="/articles/tegmental-tract">tegmental tract</a>) leads to changes in the <a href="/articles/olive">olive</a>. The olive receives inhibitory (GABAergic) signals within the dentato-rubro-olivary pathway, with transneuronal degeneration causing enlargement rather than atrophy. </p><p>Pathologically, this is characterised by "trans-synaptic degeneration resulting in vacuolation of the neurones" and an increase in astrocytes. Isolated lesions of the inferior cerebellar peduncle do not cause hypertrophic olivary degeneration, as anatomically there are no direct connections between the inferior olivary nucleus and the contralateral dentate nucleus (fibres from the inferior olivary nucleus project to the cerebellar cortex via the <a href="/articles/olivocerebellar-tract">olivocerebellar tracts</a> and then to the dentate nucleus). </p><p>Oculopalatal tremor results from disinhibition of the inferior olivary nucleus, following the pathology in dentato-rubro-olivary pathway which is further modulated by the cerebellum <sup>4</sup>. </p><h4>Radiographic features</h4><p>It is often seen several months after the original insult.</p><h5>MRI</h5><p>The inferior olivary nucleus gets larger and increases in signal intensity on T2 weighted and T2-FLAIR sequences.</p><p>Typically, within a few months, T2 signal increases and lasts for 3-4 years, whereas hypertrophy occurs later (at about one year), and resolves by 3-4 years. There are three stages:</p><ol>-<li>T2 hyperintense without olivary swelling</li>-<li>T2 hyperintense and olivary swelling occur concomitantly, developing after 6 months and persisting for nearly 3-4 years</li>-<li>olivary swelling subsides, but T2 hyperintensity persists</li>- +<p><strong>Hypertrophic olivary degeneration (HOD)</strong> is a rare condition characterised by a unique pattern of trans-synaptic degeneration. Typically it is caused by a lesion in the brainstem/cerebellum interrupting the <a href="/articles/triangle-of-guillain-and-mollaret">triangle of Guillain and Mollaret</a>, resulting in hypertrophy of the <a href="/articles/inferior-olivary-nucleus">inferior olivary nucleus</a>. </p><p>It should be noted, however, that in a significant proportion of patients no causative lesion will be identified <sup>5</sup>. </p><h4>Clinical presentation</h4><p>Oculopalatal tremor is a distinctive part of the presentation of hypertrophic olivary degeneration, although is also seen in many other brainstem and cerebellar conditions <sup>4</sup>. Oculopalatal tremor comprises ocular, palatal and other muscular involuntary movements.</p><ul>
- +<li><p>palatal myoclonus, rhythmic involuntary movement of the soft palate, uvula, pharynx, larynx and upper extremity are classically described clinical features</p></li>
- +<li><p>palatal myoclonus may not always be present, but when it is present, it is <a href="/articles/pathognomonic" title="Pathognomonic">pathognomonic</a></p></li>
- +<li><p><a href="/articles/oscillopsia" title="Oscillopsia">oscillopsia</a> may be present due to the pendular nystagmus caused by the ocular tremor <sup>4</sup></p></li>
- +</ul><h4>Pathology</h4><p>The connection between the red nucleus, ipsilateral inferior olivary nucleus and the contralateral dentate nucleus forms the triangle of Guillain and Mollaret. Interruption of either connection between the dentate nucleus and contralateral red nucleus (<a href="/articles/dentatorubral-tract">dentatorubral tract</a>, <a href="/articles/superior-cerebellar-peduncle-1">superior cerebellar peduncle</a>) or the connection between the red nucleus and ipsilateral inferior olivary nucleus (central <a href="/articles/tegmental-tract">tegmental tract</a>) leads to changes in the <a href="/articles/olive">olive</a>. The olive receives inhibitory (GABAergic) signals within the dentato-rubro-olivary pathway, with transneuronal degeneration causing enlargement rather than atrophy. </p><p>Pathologically, this is characterised by "trans-synaptic degeneration resulting in vacuolation of the neurones" and an increase in astrocytes. Isolated lesions of the inferior cerebellar peduncle do not cause hypertrophic olivary degeneration, as anatomically there are no direct connections between the inferior olivary nucleus and the contralateral dentate nucleus (fibres from the inferior olivary nucleus project to the cerebellar cortex via the <a href="/articles/olivocerebellar-tract">olivocerebellar tracts</a> and then to the dentate nucleus). </p><p>Oculopalatal tremor results from disinhibition of the inferior olivary nucleus, following the pathology in dentato-rubro-olivary pathway which is further modulated by the cerebellum <sup>4</sup>. </p><h4>Radiographic features</h4><p>Hypertrophic olivary degeneration is often seen several months after the original insult.</p><h5>MRI</h5><p>The inferior olivary nucleus gets larger and increases in signal intensity on T2 weighted and T2-FLAIR sequences.</p><p>Typically, within a few months, T2 signal increases and lasts for 3-4 years, whereas hypertrophy occurs later (at about one year), and resolves by 3-4 years. There are three stages:</p><ol>
- +<li><p>T2 hyperintense without olivary swelling</p></li>
- +<li><p>T2 hyperintense and olivary swelling occur concomitantly, developing after 6 months and persisting for nearly 3-4 years</p></li>
- +<li><p>olivary swelling subsides, but T2 hyperintensity persists</p></li>
-<li>infarction</li>-<li><a href="/articles/demyelination">demyelination</a></li>-<li><a href="/articles/astrocytic-tumours">astrocytoma</a></li>-<li>metastases</li>-<li>lymphoma</li>-<li>infection, including <a href="/articles/tuberculosis-intracranial-manifestations">tuberculosis</a>-</li>- +<li><p>infarction</p></li>
- +<li><p><a href="/articles/demyelination">demyelination</a></p></li>
- +<li><p><a href="/articles/astrocytic-tumours">astrocytoma</a></p></li>
- +<li><p>metastases</p></li>
- +<li><p>lymphoma</p></li>
- +<li><p>infection, including <a href="/articles/tuberculosis-intracranial-manifestations">tuberculosis</a></p></li>
References changed:
- 5. Gu C, Carr C, Kaufmann T, Kotsenas A, Hunt C, Wood C. MRI Findings in Nonlesional Hypertrophic Olivary Degeneration. J Neuroimaging. 2015;25(5):813-7. <a href="https://doi.org/10.1111/jon.12267">doi:10.1111/jon.12267</a>
Image 11 MRI (FLAIR) ( create )
