What is the diagnosis and treatment for a condition where the head shakes, possibly related to a movement disorder such as dystonia or essential tremor?

Head Shaking: Diagnosis and Treatment

The most likely diagnosis for head shaking depends on the clinical context: essential tremor is the most common cause in adults, while benign paroxysmal torticollis and benign myoclonus of early infancy are key considerations in young children. 1, 2

Age-Specific Differential Diagnosis

Infants and Young Children (0-3 years)

Benign myoclonus of early infancy (BMEI) should be considered first in infants presenting with head shaking between 4-7 months of age. 2

• Characterized by myoclonic jerks of the head and/or upper limbs occurring in clusters 2
• Consciousness is preserved during attacks, distinguishing it from infantile spasms 2
• Episodes last seconds but occur multiple times daily, triggered by excitement, frustration, or postural changes 2
• Attacks typically cease by age 2 years with normal development 2
• Diagnosis requires normal ictal EEG, neurological status, and development 2

Benign paroxysmal torticollis (BPT) presents with recurrent episodes of abnormal, painless head postures alternating from side to side. 2

• Onset typically before 3 months of age 2
• Episodes last minutes to several days 2
• Consider this an age-dependent migraine disorder, as migraines commonly develop later 2
• Treatment usually unnecessary unless irritability, discomfort, or vomiting require symptomatic management 2

Children and Adolescents (7-20 years)

Paroxysmal kinesigenic dyskinesia (PKD) peaks in this age group and can manifest as head movements. 2

• Male predominance (2:1 to 4:1 ratio) 2
• Triggered by sudden voluntary movements, not spontaneous 2
• Episodes last less than 1 minute in over 98% of cases 2
• Responds dramatically to low-dose carbamazepine or oxcarbazepine 2

Adults

Essential tremor (ET) is the most common adult movement disorder causing head shaking. 1

• Can present as isolated head tremor (titubation) 1
• Typically rhythmic, oscillatory movements 3
• First-line treatment: propranolol or primidone 1
• For isolated head tremor resistant to oral medications, botulinum toxin injections are effective 1

Dystonic tremor must be distinguished from ET, as it requires different management. 1

• Look for associated dystonic posturing in the neck (torticollis, laterocollis) 1
• Tremor may be irregular or jerky rather than purely rhythmic 3
• Treatment matches dystonia management, including botulinum toxin 1

Critical Red Flags Requiring Urgent Evaluation

Acute dystonia can be life-threatening when involving the neck and larynx. 4

• Sudden spastic contraction of neck muscles 4
• Most commonly occurs with high-potency dopamine D2 antagonist medications 4
• Young males at highest risk 4
• Immediate treatment: benztropine 1-2 mg IV/IM provides relief within minutes 4

Post-traumatic movement disorders occur in approximately 20% of severe head injuries. 5

• May appear or evolve months after injury 5
• Often combined with paresis, spasticity, or ataxia 5
• Exclude reversible causes including medications and metabolic derangements 5

Neurological disorders must be excluded when head shaking is accompanied by: 2

• Seizures or seizure-like episodes 2
• Parkinsonism features (early-onset Parkinson's disease has increased risk in certain genetic syndromes) 2
• Hypocalcemia-induced movement disorders (check calcium, parathyroid hormone, magnesium) 2

Diagnostic Workup Algorithm

Initial Clinical Assessment

Document specific characteristics: 2, 3

• Rhythmic vs. irregular movements (rhythmic suggests tremor, irregular suggests dystonia) 3
• Triggers: sudden movements (PKD), sustained postures (dystonia), or spontaneous (ET) 2
• Duration: seconds (BMEI, PKD), minutes to hours (BPT), or continuous (ET) 2, 1
• Age of onset and gender 2, 4
• Medication history, particularly antipsychotics 4

Laboratory Testing

Order metabolic screening when indicated: 2, 6

• Serum calcium, parathyroid hormone, magnesium (hypocalcemia can induce movement disorders) 2
• Thyroid function tests 6
• Glucose levels 6
• Ceruloplasmin if Wilson's disease suspected 6

Neuroimaging

Brain MRI is essential when: 6

• Onset after head trauma 5
• Abnormal neurological examination 6
• Age of onset over 20 years without clear etiology 2
• No response to appropriate medications 2

Neurophysiological Testing

EEG is required to: 2, 6

• Exclude seizure disorders mimicking movement disorders 2
• Confirm normal ictal activity in BMEI 2

Treatment Approach by Diagnosis

Essential Tremor with Head Involvement

Mild tremor: 1

• Non-pharmacological strategies including alcohol avoidance 1
• Consider acute pharmacological therapy for specific situations 1

Moderate tremor: 1

• Propranolol as first-line agent 1
• Alternatives: gabapentin, primidone, topiramate, alprazolam 1

Severe tremor: 1

• Thalamic deep brain stimulation or thalamotomy 1

Isolated head tremor: 1

• Botulinum toxin injections are specifically effective 1

Dystonic Head Tremor/Cervical Dystonia

Treatment matches dystonia management: 1

• Botulinum toxin injections are first-line for focal cervical dystonia 1
• Oral medications if botulinum toxin insufficient 1

Paroxysmal Kinesigenic Dyskinesia

Highly responsive to medication: 2

• Low-dose carbamazepine or oxcarbazepine (voltage-gated sodium channel blockers) 2
• Dramatic response confirms diagnosis 2

Acute Dystonia

Emergency treatment: 4

• Benztropine 1-2 mg IV/IM immediately 4
• Prophylactic antiparkinsonian agents for high-risk patients (young males on high-potency antipsychotics) 4
• Reevaluate prophylaxis need after acute phase or if antipsychotic doses lowered 4

Benign Conditions in Infancy

BMEI and BPT: 2

• Reassurance and observation as both are self-limited 2
• Symptomatic treatment only if irritability, discomfort, or vomiting present 2

Common Pitfalls to Avoid

Do not confuse dystonic movements with tremor: 3

• Dystonic movements are sustained or intermittent abnormal postures, even if repetitive 3
• Grossly arrhythmic repetitive movements should not be labeled as tremor 3
• When both coexist, describe them separately rather than using hybrid terms 3

Do not miss secondary causes: 2, 6

• Always exclude cerebrovascular disease, demyelinating disease, metabolic disorders, and brain trauma 2
• Duration of attacks exceeding 1 minute suggests alternative diagnosis 2
• Abnormal brain imaging or other neurological problems indicate secondary causes 2

Do not overlook medication-induced dystonia: 4

• High-potency dopamine antagonists carry substantially higher risk 4
• Dystonic reactions are distressing and cause medication noncompliance, increasing relapse risk 4