What are the possible causes of tremor and a feeling of shakiness two days after surgery performed under general anesthesia?

Tremor and Shakiness 2 Days Post-General Anesthesia

Primary Assessment

Tremor and shakiness occurring 2 days after general anesthesia is most likely residual neuromuscular blockade if muscle relaxants were used, postoperative pain-related tremor, or emerging postoperative delirium—not typical thermoregulatory shivering which resolves within hours. 1, 2

The timing at 2 days post-procedure is critical because:

• Immediate postoperative shaking (within hours) is typically thermoregulatory or related to residual anesthetic effects 2, 3
• Symptoms persisting to day 2 suggest alternative etiologies requiring different management 1, 4

Differential Diagnosis by Priority

1. Residual Neuromuscular Blockade (If Muscle Relaxants Were Used)

This is the most concerning cause if neuromuscular blocking agents were administered during surgery:

• Residual neuromuscular blockade can persist with incidence ranging from 4-64% when quantitative monitoring is not used 1
• Harmful consequences include generalized muscle weakness, reduced respiratory response to hypoxia, and aspiration risk 1
• Clinical signs like tremor, weakness, and difficulty with coordination may manifest as "shakiness" 1
• 37% of patients entering recovery 2+ hours after a single dose of intermediate-duration neuromuscular blocking drugs had inadequate recovery (train-of-four ratio <0.9) 1

Critical action: Verify whether quantitative neuromuscular monitoring documented train-of-four ratio >0.9 before extubation 1

2. Postoperative Delirium

Delirium occurring up to 1 week post-procedure is common, with incidence of 15-53% in older individuals:

• Postoperative delirium can present with motor disturbances including tremor and agitation 4, 5
• Advanced age is the strongest predictor, particularly patients >70 years 4
• Pre-existing cognitive impairment increases odds 3.99-fold 5
• Inadequate pain control is a significant trigger 5

Assessment priorities:

• Document cognitive status using validated delirium screening tools 5
• Distinguish from emergence delirium (which occurs immediately upon awakening, not days later) 5
• Evaluate for hypoactive delirium, which is often missed 6

3. Pain-Related Non-Thermoregulatory Tremor

Inadequate postoperative pain management can cause tremor in normothermic patients:

• Non-thermoregulatory shivering occurs in normothermic patients due to pain 2
• Adequate treatment of postoperative pain ameliorates non-thermoregulatory tremor 2

Management approach:

• Implement multimodal opioid-sparing analgesia including acetaminophen, tramadol, and gabapentin/pregabalin 5
• Avoid benzodiazepines which increase delirium risk 5

4. Functional Neurological Symptom Disorder (Rare)

A rare post-anesthetic manifestation to consider after excluding life-threatening causes:

• 86% of reported cases occur in females 7
• 93% occurred after general anesthesia 7
• 49% had history of psychiatric illness 7
• This is a diagnosis of exclusion after benign physical exam and ruling out serious pathology 7

Immediate Management Algorithm

Step 1: Exclude Life-Threatening Causes

• Assess airway patency, respiratory adequacy, and hemodynamic stability 1
• Check oxygen saturation and respiratory rate 1
• Evaluate for signs of stroke or other acute neurological events 1

Step 2: Assess Neuromuscular Function (If Muscle Relaxants Were Used)

• Perform bedside tests: sustained head-lift (>5 seconds), hand grip strength, ability to cough effectively 1
• Note: Clinical tests have poor sensitivity (10-30%) but abnormal findings are significant 1
• Consider quantitative neuromuscular monitoring if available and concerns persist 1

Step 3: Screen for Delirium

• Use validated delirium assessment tool (CAM, 4AT, or similar) 5
• Document orientation to person, place, time 5
• Assess attention span and cognitive fluctuation 4

Step 4: Evaluate Pain Control

• Assess pain scores and adequacy of current analgesic regimen 5, 2
• Implement multimodal analgesia if pain is inadequately controlled 5

Step 5: Review Medications

• Identify and discontinue any benzodiazepines or anticholinergic medications 5, 6
• These significantly increase delirium risk in vulnerable patients 5

Treatment Based on Etiology

If Residual Neuromuscular Blockade:

• Consider reversal agent if significant weakness persists 1
• Provide respiratory support as needed 1
• Monitor closely for aspiration risk 1

If Postoperative Delirium:

• Prioritize non-pharmacological interventions first: 5
  • Frequent reorientation with verbal reminders of location, time, situation 5
  • Ensure hearing aids and glasses are in place if normally used 5
  • Encourage family presence 5
  • Optimize environment: minimize noise, maintain appropriate lighting 5
• Reserve low-dose antipsychotics only for severe agitation when non-pharmacological measures fail and patient poses safety risk 5

If Pain-Related Tremor:

• Implement aggressive multimodal analgesia: 5
  • Acetaminophen as first-line 5
  • Add tramadol, gabapentin/pregabalin 5
  • Minimize opioids but use if necessary for adequate pain control 5

Critical Pitfalls to Avoid

• Do not assume tremor at day 2 is benign thermoregulatory shivering—this typically resolves within hours 2, 3
• Do not use benzodiazepines for tremor or anxiety—they worsen delirium risk 5, 6
• Do not rely solely on clinical assessment to exclude residual neuromuscular blockade—clinical tests are insensitive 1
• Do not miss hypoactive delirium—it presents without agitation but carries equal risk 6
• Do not overlook inadequate pain control as a treatable cause 5, 2

Follow-Up Considerations

• Continue structured delirium screening at least once per nursing shift if delirium is present 5
• Document cognitive trajectory as delirium is associated with lasting cognitive consequences, with changes persisting up to 7.5 years after surgery 4, 5
• Monitor for postoperative neurocognitive disorder, which can persist up to 12 months 4