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HOD

A collection of resources for individuals and families affected by Hypertrophic Olivary Degeneration (HOD).

Hypertrophic olivary degeneration (HOD) is a rare neurological disorder that leads to the degeneration of the inferior olivary nucleus. Many people with HOD have ataxia symptoms, including balance, coordination, and speech. HOD is usually an acquired form of ataxia, meaning that the HOD symptoms are the result of an injury or illness.

For complete information about symptoms, diagnosis, and treatment of Ataxia, visit our What is Ataxia? page. This page contains NAF’s resources that are specific to HOD. You can also learn more about HOD through the Hypertrophic Olivary Degeneration Association.   

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Webinar

All About HOD

Presented by Vikram Shakkottai, MD, PhD

During this webinar, an expert will discuss Hypertrophic Olivary Degeneration, including the typical diagnostic journey for those affected, what to expect for clinical care, and an overview of current research. This information may also be helpful for individuals with MSA, SCA1, SCA2 and SCA7 who have olivary degeneration.

NAF offers webinars on many topics to help you live better with Ataxia. Visit www.ataxia.org/webinars to find other helpful presentations.

HOD Information

Hypertrophic olivary degeneration (HOD) is caused by the inferior olivary nucleus growing larger than normal. This causes HOD symptoms to start. There are two olives, located on each side of the brain stem. The olives assist the cerebellum to learn new movement and coordinate the body. HOD can affect one olive (unilateral) or both olives (bilateral). 

There are multiple potential reasons that the inferior olivary nucleus grows larger and causes HOD. This includes stroke, brainstem malformations or damage, side effects of other neurodegenerative disorders, demyelinating diseases such as Multiple Sclerosis, or for unknown reasons.  There can be a delay between the initial damage to the olive and the HOD symptoms starting.

There is still a lot we do not know about why HOD happens. Research is being done to better understand the root causes of HOD.

HOD Symptoms

Over 70% of people with HOD have ataxia. Ataxia means incoordination. These symptoms can include problems with balance, coordination, and dexterity.  Ataxia can also include problems coordinating muscles that control speech and swallowing.

Many people with HOD have vision symptoms, such as double vision or nystagmus. Other symptoms include numbness, feeling dizzy, tinnitus, muscle spasticity, involuntary muscle twitching, and tremors.

HOD Prognosis

It can be hard to predict how HOD symptoms will progress over time. This is due to the limited information available on HOD currently. Research is being done to better understand when symptoms start and how they progress.

The stability of symptoms depends on the underlying causes of HOD. For HOD due to injury, such as a brainstem bleed, symptoms usually become stable and do not get worse after some time. For HOD due to illness, such as MSA-C, symptoms will slowly get worse over time.

Treatments such as physiotherapy, occupational therapy, and speech-language therapy can significantly improve the lives of people with HOD. There are no medications approved to treat HOD at this time. However, medications can be used to treat specific symptoms – such as tremor or ataxia.

HOD Diagnosis

A neurologic examination can determine whether a person has symptoms typical of HOD. This suspected diagnosis is then confirmed through brain imaging, such as MRI. A neurologist is often the most helpful specialist in recognizing symptoms and diagnosing HOD.

HOD Research News

SCAsource provides Ataxia research news, directly from researchers to the Ataxia community. Visit SCAsource to see their full collection. Here is a collection of articles relevant to HOD. 

Snapshot: What is Nystagmus?

Nystagmus, also known as ocular ataxia, is a term that refers to uncontrollable eye movement- usually a repetitive cycle of slow movement in a specific direction followed by a quick Read More…

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