What is the best approach to manage tremor in an adult patient with a neurological condition, such as essential tremor or parkinsonian tremor, and a history of asthma or chronic obstructive pulmonary disease (COPD)?

Tremor Management in Patients with Asthma or COPD

For adult patients with essential tremor or parkinsonian tremor who have asthma or COPD, primidone should be the first-line pharmacological treatment, as beta-blockers like propranolol are contraindicated due to the risk of bronchospasm. 1, 2

Initial Diagnostic Approach

Determine tremor type by observing when it occurs:

• Resting tremor that improves with movement indicates Parkinsonian tremor and requires evaluation for Parkinson's disease 3
• Postural/action tremor that worsens with goal-directed activity suggests essential tremor 3
• Assess functional impact on daily activities, as treatment is only initiated when tremor interferes with function or quality of life 1, 2

First-Line Pharmacological Treatment

For Essential Tremor in Patients with Respiratory Disease

Primidone is the preferred first-line agent when beta-blockers are contraindicated:

• Primidone demonstrates efficacy comparable to propranolol in up to 70% of patients 1, 2
• Critical timing consideration: Clinical benefits may not become apparent for 2-3 months, so an adequate trial period is essential before declaring treatment failure 1, 3
• Therapeutic benefit can occur even when derived phenobarbital levels remain subtherapeutic, confirming primidone itself has anti-tremor properties 1

Important side effects to monitor:

• Behavioral disturbances, irritability, and sleep disturbances can occur, particularly at higher doses 1, 3
• Women of childbearing age require counseling about teratogenic risks (neural tube defects) 1, 2, 3

Why Beta-Blockers Must Be Avoided

Propranolol and other beta-blockers are absolutely contraindicated in patients with asthma or COPD:

• Beta-blockers can cause bronchospasm in asthmatic patients 1
• The American Academy of Allergy, Asthma, and Immunology specifically recommends avoiding beta-blockers such as propranolol in patients with asthma or COPD due to this risk 1
• Additional contraindications for beta-blockers include bradycardia and congestive heart failure 1, 2, 3

Second-Line Options

If primidone fails or is not tolerated:

• Gabapentin has limited evidence for moderate efficacy in tremor management 1
• Consider other second-line agents before proceeding to surgical options 1

Non-Pharmacological Interventions

For functional tremor specifically, rhythm modification techniques can be highly effective:

• Superimpose alternative voluntary rhythms on existing tremor and gradually slow movement to complete rest 4, 3
• For unilateral tremor, use the unaffected limb to dictate a new rhythm (e.g., tapping/opening and closing the hand) to entrain the tremor to stillness 4
• Use gross rather than fine movements, such as handwriting retraining with a marker and large paper rather than focusing on normal handwriting 4
• Discourage cocontraction or tensing of muscles as a method to suppress tremor, as this is unlikely to be a helpful long-term strategy 4

Critical pitfall to avoid: Do not provide adaptive equipment in the acute phase, as this prevents recovery by reinforcing maladaptive movement patterns 4, 3

Surgical Options for Medication-Refractory Tremor

Consider surgical interventions when medications fail due to lack of efficacy at maximum doses, dose-limiting side effects, or medical contraindications 1, 2, 3:

For Unilateral Tremor

Magnetic Resonance-Guided Focused Ultrasound (MRgFUS) Thalamotomy is preferred:

• Shows sustained tremor improvement of 56% at 4 years 1, 2, 3
• Lower complication rate (4.4%) compared to radiofrequency thalamotomy (11.8%) and deep brain stimulation (21.1%) 1, 3
• Early adverse effects include gait disturbance (36%) and paresthesias (38%), which decrease to 9% and 14% respectively by 1 year 1
• Serious adverse events are rare (1.6%), with most being mild or moderate (98.4%) and more than 50% resolving by 1 year 1

MRgFUS contraindications:

• Cannot undergo MRI 1
• Skull density ratio <0.40 1
• Bilateral treatment needed or contralateral to previous thalamotomy 1

For Bilateral Tremor

Deep Brain Stimulation (DBS) of the ventral intermediate nucleus (VIM) of the thalamus:

• Provides adjustable, reversible tremor control that can be optimized over time 1, 3
• Preferred for relatively young patients as it offers an adjustable treatment option 1
• Higher complication rate (21.1%) than MRgFUS but allows bilateral treatment 1, 3

Parkinsonian Tremor Management

For patients with Parkinson's disease tremor:

• Levodopa is the first-line therapeutic option for all motor symptoms, including tremor 5
• Addition of dopamine agonists or anticholinergics can lead to further tremor reduction 5
• Botulinum toxin injection is an effective alternative for patients with pharmacological-resistant tremor who are not seeking advanced therapies 5

Common Pitfalls

• Do not stop primidone before 2-3 months—therapeutic benefit may not become apparent for this duration 3
• Do not assume all resting tremors are Parkinson's disease—combination of resting tremor with prominent early gait difficulties and falls is atypical for classic Parkinson's and should raise suspicion for atypical parkinsonism 3
• Do not overlook medication-induced tremor—review all medications for tremor-inducing agents including antiparkinsonians, lithium, sympathomimetics, and antipsychotics 3