Harding’s disease is an early cerebellar ataxia, a neurological disease of the cerebellum or brainstem that impairs movement coordination, walking and the ability to articulate.

Early cerebellar ataxia with conservation of tendon reflexes, more simply called Harding’s disease Where Harding’s ataxia is neurological disease of the cerebellum or brainstem. It is a disorder of the coordination of movements, with however a conservation of the muscular force and certain reflexes. What exactly is a cerebellar ataxia? What are the signs ? How to treat this disease? With rehabilitation? Medication ? What life expectancy?

Definition: what is Harding’s disease?

The Harding’s disease Where Harding’s ataxia is medically called cerebellar ataxia early with preservation of tendon reflexes (ACPCRT). A cerebellar ataxia is “a neurodegenerative pathology of the cerebellum (part of the brain located under the brain and behind the brainstem, editor’s note) and/or brainstem which translates into disorders of the coordination of voluntary movements without muscle weakness, balance and eye damage“, indicates theBrain Institute (ICM).

What are the symptoms of Harding’s disease?

Early cerebellar ataxia with conservation of tendon reflexes (meaning that muscle strength and tendon reflexes are preserved) or Harding’s ataxia can manifest as:

  • Movements involuntary bodily injury
  • Movements difficult to master
  • An approach hesitant, uncoordinatedas if the patient were walking in a swamp (ataxic gait)
  • An inability to articulate words normally (dysarthria)
  • An involuntary, jerky oscillation of the eyeball (nystagmus)
  • Lack of ankle reflex, an expected reflex during percussion of the Achilles tendon
  • Occasionally : oculomotor disorders, dysphagia (swallowing disorder), tremor, scoliosis, hollow feet, as well as emaciation and weakness of the lower limbs without amyotrophy can be observed.
Mechanism and cause of ataxia © VectorMine – / Women’s Journal

What are the possible causes of Harding’s disease?

The exact origin of Harding’s disease still remains unknown. Nevertheless, a study published in March 2018 in the Revue Neurologie (available on EM Consulte) and carried out on a Tunisian cohort has highlighted, thanks to a molecular genetic analysis, the hereditary character of this syndrome (genetic heterogeneity) and located the gene locus (fixed position of a gene on a chromosome) on the chromosome 13q11-12.

Is it a hereditary disease?

To date, nothing is sure about the hereditary nature of Harding’s ataxia. Only the study conducted on the Tunisian cohort, presented beforehand, indicates possible genetic heterogeneity.

How many cases of Harding’s disease in the world?

The prevalence of Harding’s disease has been estimated at around 1/100,000can we read on the site of the network of rare diseases Orphanet. Harding’s disease is therefore considered to be a rare disease.

Harding’s ataxia is a cerebellar ataxia that is progressive and who would be slowly growing: she appears usually during childhood or adolescence (between ages 3 and 20, with an average age of 9 years). The latency period before the patient has need a wheelchair is significantly longer in Harding’s disease than in other ataxias such as Friedreich’s ataxia.

Diagnosis is based primarily on clinical examination as well as the results of several imaging tests (magnetic resonance imaging (MRI) or computed tomography (CT)) highlighting a atrophy of the cerebellum or brainstem. Sometimes peripheral nerve conduction (measured by electrical impulses) or peripheral nerve biopsy also helps make the diagnosis. During the diagnosis, it is also necessary to eliminate the track of a Friedreich’s ataxia (another type of ataxia) which, unlike Harding’s ataxia, manifests as cardiomyopathy, diabetes mellitus, scoliosis, skeletal malformations or optic atrophy, and also rules out other types of ataxia ( autosomal dominant cerebellar ataxia, autosomal recessive spastic ataxia of Charlevoix-Saguenay, vitamin E deficiency ataxia) as well as metabolic disorders acquired that may express ataxia.

What is the treatment for Harding’s disease? Rehabilitation?

Treatment of Harding’s disease is symptomatic, aimed at controlling the involuntary muscle stiffness and motor deficit. The treatment includes rehabilitation with a physiotherapist and the prescription of medications which may include spasmolytic agents, such as baclofen. Loccupational therapy or thespeech therapy can also relieve symptoms, specifies the Institut du Cerveau website.

What life expectancy?

Unlike other ataxias, in the case of cerebellar ataxia, “evolution is generally slower and not life-threateningcan we read in the Letter from the Neurologist n°8 of October 2013 on “Spinocerebellar ataxias”

Sources: Orphanet / Brain Institute / College of Neurology Teachers website: “Semiology of ataxias, gait disorders and dysarthrias” / Rouen-Normandy University Hospital / Neurogenetics Reference Center, report from the High Authority for Health (HAS).

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