What is the management approach for paroxysmal sympathetic hyperactivity?

Management of Paroxysmal Sympathetic Hyperactivity

Paroxysmal sympathetic hyperactivity (PSH) after acquired brain injury requires a three-tiered pharmacologic approach: scheduled preventive medications (typically combining gabapentin, propranolol, and clonidine), abortive therapy for breakthrough episodes (morphine and short-acting benzodiazepines), and aggressive reduction of environmental stimulation. 1, 2, 3

Initial Recognition and Assessment

• Use the PSH Assessment Measure (PSH-AM) tool for early identification and severity stratification, as it is currently the optimal diagnostic instrument 4
• PSH typically presents with episodic tachycardia, hypertension, tachypnea, hyperthermia, diaphoresis, and dystonic posturing 3, 5
• Most commonly occurs in young comatose patients with severe traumatic brain injury, though increasingly recognized in stroke patients where tachycardia and hypertension predominate 4, 3

Pharmacologic Management Strategy

Preventive Medications (First-Line Scheduled Therapy)

The goal is to prevent episodes before they occur using regularly scheduled medications, typically requiring combination therapy from multiple drug classes. 2, 5

• Gabapentin: Primary preventive agent targeting sympathetic hyperactivity 3, 5
• Propranolol: Nonselective β-blocker to control tachycardia and hypertension 2, 3, 5
• Clonidine: α2-agonist to reduce central sympathetic outflow 2, 3, 5
• Long-acting benzodiazepines: For baseline sedation and muscle tone reduction 2, 5
• Morphine: Scheduled opioid therapy to reduce afferent stimulation 2, 3
• Baclofen: GABA agonist particularly useful when dystonia is prominent 2, 5

Abortive Therapy (Breakthrough Episodes)

• Intravenous morphine: First-line for acute symptom control during discrete episodes 3, 5
• Short-acting benzodiazepines: For rapid control of breakthrough sympathetic surges 2, 5

Symptom-Specific Targeting

Tailor medication selection based on predominant symptom presentation: 1

• For sympathetic hyperactivity dominance: Prioritize propranolol and clonidine
• For pain manifestations: Emphasize morphine and gabapentin
• For muscle hypertonicity/dystonia: Add baclofen and benzodiazepines

Non-Pharmacologic Interventions

• Minimize external stimulation: Reduce noise, limit unnecessary procedures, control room temperature, and minimize handling 3, 5
• These environmental modifications are critical as external stimuli trigger episodes 3

Critical Pitfalls to Avoid

• Never rely on monotherapy: Combination therapy from different drug classes is consistently more effective than single agents 2, 5
• Avoid oversedation: Balance symptom control against the need for neurologic assessment and rehabilitation participation 5
• Do not delay treatment: PSH is associated with worse neurologic outcomes, longer hospitalizations, increased complications (dehydration, weight loss, muscle contractures), and higher costs 2, 3, 5
• Do not mistake PSH for infection: Fever and tachycardia may prompt unnecessary antibiotic use; use PSH-AM for proper diagnosis 4

Treatment Escalation Algorithm

1. Start with scheduled gabapentin + propranolol + clonidine as the foundational triple therapy 3, 5
2. Add morphine if episodes persist despite initial therapy 2, 3
3. Add long-acting benzodiazepines for refractory cases or prominent dystonia 2, 5
4. Add baclofen when muscle hypertonicity is a major component 2, 5
5. Maintain short-acting morphine and benzodiazepines available for breakthrough episodes throughout treatment 5

Evidence Limitations

• Current evidence consists primarily of case reports and case series; no randomized controlled trials exist 2
• Wide variability exists in clinical practice regarding specific drug choices, dosing, and duration of therapy 2
• The mechanisms by which these agents improve PSH symptoms remain speculative 2
• Future research using the standardized PSH-AM tool is needed to establish evidence-based treatment protocols 2