Ross syndrome (RS) is a rare disorder of the peripheral autonomic nervous system that is characterized by the triad: tonic pupils, reduced or loss of deep tendon reflexes (hyporeflexia or areflexia), and anhidrosis or hypohidrosis.
Causes of Ross Syndrome
The exact pathogenesis of RS is not known.
However, researchers believe there is a nonspecific degeneration of parasympathetic neuronal structures.
Anhidrosis or hypohidrosis likely stems from degeneration of sympathetic ganglion cells or postganglionic projections.
There also appears to be a loss of regulation of skin blood flow resulting in upper large and dilated dermal blood vessels.
The tonic pupil stems from damage to the ciliary ganglion or postganglionic parasympathetic nerve fibers.
The loss of deep tendon reflexes may stem from damage to the dorsal root ganglia or spinal interneuron loss.
Symptoms of Ross Syndrome
RS presents with unilateral or bilateral anhidrosis, tonic pupils, and hyporeflexia.
Additionally, various symptoms of autonomic dysfunction in RS may include gastrointestinal paresis, impotence and sexual dysfunction, orthostatic hypotension, Parkinsonism, and urinary incontinence.
Diagnosis of Ross Syndrome
The diagnosis of RS is usually clinical but the complete RS triad may not be present initially.
The tonic pupil produces variable anisocoria that is worse in the light than in the dark.
The pupillary reaction to light is typically impaired but preserved to accommodative stimulus (i.e. light-near dissociation).
In the RS, the pupil abnormality is typically bilateral.
Light near dissociation of the pupils is not specific for the RS and can also be found in patients with bilateral anterior afferent visual pathway disease, Argyll Robertson pupil, diabetes, or dorsal midbrain lesions.
The denervated sphincter muscles can show increased sensitivity to diluted pilocarpine (0.125%) due to up regulation of receptors in up to 80% of cases.
Treatment of Ross Syndrome
Currently, therapeutic options for RS are restricted to symptomatic management.
Therapeutic options for RS are similar to other primary or secondary hyperhidrosis.
General cooling measures including wearing loose clothing and avoiding hot environments or heavy exertion are recommended.
Antiperspirants containing aluminium chloride 10–25% are also used to prevent excess sweating but may worsen over heating.
There have been research that also shows anticholinergic medications including oxybutynin and glycopyrrolate to inhibit the effect of acetylcholine on the sweat glands.
While they can be useful to reduce sweating, there are side effects, including dry mouth, blurred vision, constipation, and urinary retention.
Botulinum toxin injections, iontophoresis, and sympathectomy, have also been used in the treatment of severe hyperhidrosis.
For patients with ANA positivity, Vasudevan et al presented a case of a patient with ANA positivity who was successfully treated with intravenous immunoglobulin.