Ross' syndrome

Overview

Ross' syndrome is a rare neurological disorder classified as a type of autonomic neuropathy. It is characterized by a triad of clinical features: segmental anhidrosis (loss of sweating in specific areas), areflexia or hyporeflexia (absent or reduced deep tendon reflexes), and tonic pupil (also known as Adie’s pupil), which reacts sluggishly to light but may constrict during near vision (accommodation).

Ross' syndrome is considered a slowly progressive disorder of the peripheral autonomic nervous system. It often affects middle-aged adults but can present at various ages. Though not life-threatening, it can significantly impact quality of life due to thermoregulatory disturbances and vision discomfort. The condition may be misdiagnosed or mistaken for other forms of autonomic dysfunction or Adie’s syndrome, to which it is closely related.

Causes

The exact cause of Ross' syndrome remains unclear, but it is believed to be a form of peripheral autonomic neuropathy, possibly immune-mediated in some cases. The disorder involves selective damage to postganglionic autonomic fibers, particularly those involved in sweat gland function and the pupillary light reflex.

Proposed Contributing Factors:

• Idiopathic: Most cases occur without a known cause

• Autoimmune mechanisms: Suggested in some patients, possibly linked to other autoimmune neuropathies

• Viral infections: Suspected triggers in some reports

• Genetic predisposition: Not commonly observed but may play a role in rare cases

Association with Other Conditions:

• Adie’s syndrome (tonic pupil with diminished reflexes)

• Holmes-Adie syndrome (a closely related condition with overlapping features)

• Other autonomic neuropathies, including diabetes-related neuropathy or post-viral syndromes

Symptoms

Ross' syndrome presents with a specific combination of neurological signs. Symptoms typically progress slowly over years and may initially affect only one side of the body before becoming more widespread.

Core Triad of Symptoms:

• Segmental anhidrosis or hypohidrosis: Patchy loss of sweating, usually on the trunk, limbs, or face. Often accompanied by compensatory hyperhidrosis (excess sweating) in unaffected areas.

• Tonic (Adie’s) pupil: A dilated pupil that reacts poorly to light but may respond better to near vision (light-near dissociation). It may cause photophobia or blurred vision for close work.

• Areflexia or hyporeflexia: Reduced or absent deep tendon reflexes, particularly in the knees or ankles. Usually not associated with motor weakness.

Additional Symptoms:

• Heat intolerance due to impaired thermoregulation

• Fatigue and dizziness in hot environments

• Facial flushing or asymmetrical sweating

• Blurred or fluctuating vision due to pupillary abnormalities

• Occasional lightheadedness or orthostatic intolerance (rare)

Diagnosis

Ross' syndrome is diagnosed through clinical examination and tests assessing autonomic function, pupillary response, and reflexes. Because it is a diagnosis of exclusion, other neurological or systemic disorders must be ruled out.

Clinical Evaluation:

• Detailed neurological examination to assess deep tendon reflexes

• Ophthalmologic assessment of pupil size and reactivity

• Evaluation of sweating patterns (patient-reported or observed)

Autonomic Function Testing:

• Thermoregulatory sweat testing (TST): Visualizes areas of anhidrosis and compensatory hyperhidrosis

• Quantitative sudomotor axon reflex test (QSART): Measures sweat gland function and identifies segmental loss

• Pupil light reflex testing: Identifies tonic pupil and light-near dissociation

Other Diagnostic Tools:

• Slit-lamp examination: Confirms Adie’s pupil

• Neurological tests: Nerve conduction studies to rule out peripheral neuropathies

• Blood tests: To exclude autoimmune or infectious causes

Differential Diagnosis:

• Adie’s syndrome (without segmental anhidrosis)

• Holmes-Adie syndrome

• Diabetic autonomic neuropathy

• Multiple system atrophy (MSA) or other neurodegenerative disorders

Treatment

There is no cure for Ross' syndrome. Treatment is symptomatic and focused on managing the effects of autonomic dysfunction, particularly sweating abnormalities and pupillary symptoms. Most patients benefit from lifestyle adjustments and supportive care.

1. Management of Sweating Abnormalities:

• Anticholinergic medications: Such as glycopyrrolate or oxybutynin to reduce compensatory hyperhidrosis

• Topical treatments: Aluminum chloride-based antiperspirants

• Botulinum toxin injections: Target areas of excessive sweating for temporary relief

• Cooling devices and clothing: Help mitigate heat intolerance

2. Management of Tonic Pupil:

• Pilocarpine eye drops (low concentration): May help constrict the tonic pupil and improve near vision

• Photochromic or tinted lenses: To reduce light sensitivity

3. Monitoring and Supportive Care:

• Regular neurological and ophthalmological evaluations

• Physical therapy may help manage areflexia if associated with discomfort or imbalance

• Patient education on avoiding overheating and dehydration

Prognosis

Ross' syndrome is a chronic, slowly progressive condition. Although it can significantly impact quality of life especially due to thermoregulatory dysfunction, it is not life-threatening. The progression is usually slow, and the syndrome tends to remain confined to autonomic features without major systemic involvement.

Most patients adapt to the condition with appropriate lifestyle changes and symptom management. With supportive care, visual function and general health can be preserved. Emotional support and counseling may also benefit individuals dealing with the visible and functional effects of the disorder.

Because the syndrome is so rare, long-term studies are limited, but the overall prognosis is considered stable with proper monitoring and intervention.