Adult-onset autosomal recessive cerebellar ataxia

What it is

From: Orphanet

A rare, genetic, autosomal recessive cerebellar ataxia disease characterized by adulthood-onset of slowly progressive spinocerebellar ataxia, manifesting with gait and appendicular ataxia, dysarthria, ocular movement anomalies (e.g. horizontal, vertical, and/or downbeat nystagmus, hypermetric saccades), increased deep tendon reflexes and progressive cognitive decline. Additional variable features may include proximal leg muscle wasting and fasciculations, pes cavus, inspiratory stridor, epilepsy, retinal degeneration and cataracts. Brain imaging reveals marked cerebellar atrophy and electromyography shows evidence of lower motor neuron involvement.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Abnormal enzyme/coenzyme activity · Very frequent (99-80%)

Concentration or activity of an enzyme is above or below the limits of normal in the blood circulation.

Progressive cerebellar ataxia · Very frequent (99-80%)

Ankle clonus · Frequent (79-30%)

Clonus is an involuntary tendon reflex that causes repeated flexion and extension of the foot. Ankle clonus is tested by rapidly flexing the foot upward.

Brisk reflexes · Frequent (79-30%)

Tendon reflexes that are noticeably more active than usual (conventionally denoted 3+ on clinical examination). Brisk reflexes may or may not indicate a neurological lesion. They are distinguished from hyperreflexia by the fact that hyerreflexia is characterized by hyperactive repeating (clonic) reflexes, which are considered to be always abnormal.

Cerebellar atrophy · Frequent (79-30%)

Cerebellar atrophy is defined as a cerebellum with initially normal structures, in a posterior fossa with normal size, which displays enlarged fissures (interfolial spaces) in comparison to the foliae secondary to loss of tissue. Cerebellar atrophy implies irreversible loss of tissue and result from an ongoing progressive disease until a final stage is reached or a single injury, e.g. an intoxication or infectious event.

Downbeat nystagmus · Frequent (79-30%)

Downbeat nystagmus is a type of fixation nystagmus with the fast phase beating in a downward direction. It generally increases when looking to the side and down and when lying prone.

Dysarthria · Frequent (79-30%)

Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed.

Dysmetria · Frequent (79-30%)

A type of ataxia characterized by the inability to carry out movements with the correct range and motion across the plane of more than one joint related to incorrect estimation of the distances required for targeted movements.

Dysmetric saccades · Frequent (79-30%)

The controller signal for saccadic eye movements has two components: the pulse that moves the eye rapidly from one point to the next, and the step that holds the eye in the new position. When both the pulse and the step are not the correct size, a dysmetric refixation eye movement results.

EMG abnormality · Frequent (79-30%)

Abnormal results of investigations using electromyography (EMG).

Fasciculations · Frequent (79-30%)

Fasciculations are observed as small, local, involuntary muscle contractions (twitching) visible under the skin. Fasciculations result from increased irritability of an axon (which in turn is often a manifestation of disease of a motor neuron). This leads to sporadic discharges of all the muscle fibers controlled by the axon in isolation from other motor units.

Generalized-onset seizure · Frequent (79-30%)

A generalized-onset seizure is a type of seizure originating at some point within, and rapidly engaging, bilaterally distributed networks. The networks may include cortical and subcortical structures but not necessarily the entire cortex.

Hyperreflexia · Frequent (79-30%)

Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles.

Limb ataxia · Frequent (79-30%)

A kind of ataxia that affects movements of the extremities.

Other findings in the same source

From: Orphanet

Additional reported features include Macular degeneration (Frequent (79-30%)); Pes cavus (Frequent (79-30%)); Progressive gait ataxia (Frequent (79-30%)); Ptosis (Frequent (79-30%)); Saccadic smooth pursuit (Frequent (79-30%)); Slurred speech (Frequent (79-30%)); Truncal ataxia (Frequent (79-30%)); Leg muscle stiffness (Frequent (79-30%)); Cataract (Occasional (29-5%)); Diplopia (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Adult

Inheritance in the source

From: Orphanet

Autosomal recessive

Frequency and the population described

From: Orphanet

Point prevalence: <1 / 1 000 000; Worldwide; Class only. Reported case(s): 14.0; Worldwide. This is a published case count, not prevalence.

Understanding the inheritance label

From: MedlinePlus Genetics

An autosomal recessive pattern usually involves disease-causing changes in both copies of a gene. Parents may each carry one altered copy without having the condition themselves. A genetic counsellor can explain carrier testing and reproductive implications using the actual laboratory findings, rather than the condition name alone.

Which doctor should you see?

The suggested department for discussing Adult-onset autosomal recessive cerebellar ataxia is Neurology, with a neurologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which nervous-system findings help explain the symptoms?
• Would an assessment of walking, communication or daily function be helpful?
• Are rehabilitation or other specialist services relevant?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Adult-onset autosomal recessive cerebellar ataxia. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.