Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis

Alternate names

• SANDO

Definition

Sensory ataxic neuropathy-dysarthria-ophthalmoparesis syndrome is characterized by adult-onset severe sensory ataxic neuropathy, dysarthria and chronic progressive external ophthalmoplegia.

Epidemiology

The prevalence is unknown.

Cause

The syndrome is associated with mitochondrial DNA mutations in either the POLG1 or TWINKLE genes.

Inheritance

Autosomal recessive and dominant inheritance, as well as sporadic occurrence, have been suggested.

Signs and symptoms

Other common features include progressive gait unsteadiness, absent deep tendon reflexes, the presence of Rhomberg sign, a decreased sense of vibration and proprioception and detection of red ragged fibres on muscle biopsy.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 30%-79% of people have these symptoms

• Abnormal morphology of the cerebellar cortex
• Abnormal thalamic MRI signal intensity
• Atrophy/Degeneration involving the spinal cord
• Bilateral sensorineural hearing impairment
• Dysarthria(Difficulty articulating speech)
• Gait ataxia(Inability to coordinate movements when walking)
• Hyporeflexia(Decreased reflex response)
• Impaired distal proprioception
• Impaired vibratory sensation(Decreased vibration sense)
• Increased serum lactate
• Increased variability in muscle fiber diameter
• Myoclonus
• Nystagmus(Involuntary, rapid, rhythmic eye movements)
• Ophthalmoparesis(Weakness of muscles controlling eye movement)
• Positive Rhomberg sign
• Proximal muscle weakness(Weakness in muscles of upper arms and upper legs)
• Ptosis(Drooping upper eyelid)
• Ragged-red muscle fibers
• Sensory ataxic neuropathy
• Upgaze palsy
• Vestibular dysfunction

5%-29% of people have these symptoms

• Areflexia(Absent tendon reflexes)
• Cataract(Clouding of the lens of the eye)
• Depressivity(Depression)
• Dilated cardiomyopathy(Stretched and thinned heart muscle)
• [[Gastroparesis](Delayed gastric emptying)
• Intestinal pseudo-obstruction
• Memory impairment(Forgetfulness)
• Migraine (Intermittent migraine headaches)
• Seizure

Diagnosis

Establishing the diagnosis of a POLG-related disorder relies on clinical findings and identification of biallelic POLG pathogenic variants for all phenotypes except adPEO, for which identification of a heterozygous POLG pathogenic variant is diagnostic.[1].

Treatment

Clinical management is largely supportive and involves conventional approaches for associated complications including occupational, physical, and speech therapy; nutritional interventions; and standard respiratory support, treatment for liver failure and disorders of arousal and sleep, and management of seizures and movement disorders.

References

Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis Resources
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NIH genetic and rare disease info

• NIH info on Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis

Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis is a rare disease.