progressive supranuclear palsy

progressive supranuclear palsy
Synonyms	Steele–Richardson–Olszewski syndrome
Field	Neurology

progressive supranuclear palsy is a rare and progressive brain disorder that affects movement, balance, speech, swallowing, vision, mood, and thinking. It is classified as a tauopathy, a type of neurodegenerative disease involving the abnormal accumulation of the tau protein in the brain. The condition leads to damage in specific areas of the brainstem, basal ganglia, and cerebral cortex, resulting in its characteristic symptoms. There is currently no cure, and management focuses on alleviating symptoms and providing supportive care.

Signs and symptoms

The most distinctive early sign is a loss of balance leading to frequent falls, often backwards. Patients typically develop a progressive supranuclear gaze palsy, a profound difficulty with voluntary eye movements, particularly looking downward. This is often accompanied by axial rigidity, bradykinesia, and a stiff, unsteady gait that can resemble Parkinson's disease. Other common features include dysarthria, dysphagia, cognitive impairment, apathy, and pseudobulbar affect. Unlike in Parkinson's disease, a tremor is usually absent.

Causes and pathophysiology

The primary cause is the abnormal aggregation of the tau protein into neurofibrillary tangles within neurons and glial cells, particularly in the substantia nigra, subthalamic nucleus, globus pallidus, and superior colliculus. This pathological process leads to the degeneration of these critical brain regions. While most cases are sporadic, research has identified certain genetic variations in the MAPT gene, which encodes the tau protein, as significant risk factors. The exact trigger for the tau misfolding remains unknown.

Diagnosis

Diagnosis is primarily clinical, based on a detailed neurological examination and patient history, often following established criteria such as the Movement Disorder Society diagnostic criteria. Key diagnostic clues include the early onset of postural instability, vertical gaze palsy, and poor response to levodopa. Magnetic resonance imaging may show characteristic atrophy of the midbrain, sometimes described as the "hummingbird sign" on sagittal views or the "morning glory sign" on axial views. DaTscan imaging can help differentiate it from Parkinson's disease.

Treatment and management

There is no disease-modifying therapy. Treatment is symptomatic and multidisciplinary, involving neurologists, physiatrists, speech-language pathologists, and occupational therapists. Medications such as levodopa or amantadine may offer modest or transient improvement in motor symptoms for some patients. Botulinum toxin injections can be used for blepharospasm or neck dystonia. Supportive care includes physical therapy for balance, communication aids for speech difficulties, and dietary modifications or percutaneous endoscopic gastrostomy for severe dysphagia.

Prognosis and epidemiology

The disease is relentlessly progressive, with a median survival of approximately 6 to 9 years from symptom onset. Death is typically due to complications such as pneumonia or pulmonary embolism resulting from immobility and dysphagia. It is considered a rare disease, with an estimated prevalence of 3 to 6 per 100,000 people. Onset is typically in the sixth or seventh decade of life, and it appears to affect men slightly more often than women. No specific geographic or ethnic predominance has been firmly established.

History

The condition was first clearly delineated as a distinct clinicopathological entity in 1964 by Canadian neurologists John Steele, J. Clifford Richardson, and Polish-born neurologist Jerzy Olszewski, who described it in a seminal paper published in the Archives of Neurology. Their work distinguished it from other parkinsonian syndromes, leading to the eponym **Steele–Richardson–Olszewski syndrome**. Earlier, possible cases had been described by Charcot and others but were not fully characterized.

Category:Neurodegenerative disorders Category:Movement disorders Category:Tauopathies