Neurology
A 21 year old man, with known schizophrenia, presents to the Emergency Department complaining that he is unable to move his neck, and it has been locked to the left hand side for the past 4 hours. What is the most likely diagnosis?
Answer:
Acute dystonia is a movement disorder in which there is a state of abnormal tone produced by slow and sustained contractions of opposing muscle groups. These contractions are painful. They often provoke anxiety. Although dystonias may occur in any muscle group, they most commonly affect muscles in the head and neck. The commonest cause of acute dystonia is prescribed medication. Acute dystonic reactions have been associated with the majority of antipsychotics; with the older or typical neuroleptics, such as haloperidol, dystonias occur in 15-20% of patients. The risk is less with the newer or atypical medications such as clozapine, risperidone, olanzapine and quetiapine (<5%).Acute Dystonic Reaction
Neurology
Last Updated: 12th February 2021
Acute dystonia is a movement disorder in which there is a state of abnormal tone produced by slow and sustained contractions of opposing muscle groups. These contractions are painful. They often provoke anxiety. Although dystonias may occur in any muscle group, they most commonly affect muscles in the head and neck. Usually only one muscle group is affected, though in approximately 20% of cases the phenomenon may affect more than one muscle group.
The pathogenesis of acute dystonia is not fully understood. It is thought to be related to dopamine-receptor blockade, which disrupts the dopaminergic-cholinergic balance in the basal ganglia (substantia nigra) leading to a relative excess of cholinergic output.
Although acute dystonia can occur at any age, it is 2-3 times more common in patients under 35 and there is a linear decrease with age. In patients under 50 years of age, the incidence in men is twice that in women. The incidence of medication induced dystonias in the over 50s is the same for men and women. Risk factors for acute dystonia include family history, young age, male sex, previous history of drug induced dystonia and cocaine use.
Causes
The commonest cause of acute dystonia is prescribed medication. Usually such cases present shortly after initiation of drug treatment, with 50% occurring within 48 hours, and 90% within five days of initiation of therapy. Acute dystonia can be dose related but is often idiosyncratic.
Commonly implicated medications:
- Neuroleptics (antipsychotics)
- Acute dystonic reactions have been associated with the majority of antipsychotics; with the older or typical neuroleptics, such as haloperidol, dystonias occur in 15-20% of patients. The risk is less with the newer or atypical medications such as clozapine, risperidone, olanzapine and quetiapine (<5%).
- Antiemetics
- Metoclopramide, droperidol, prochlorperazine, promethazine
- Antidepressants
- SSRIs
- Other medication
- Gastrointestinal medication e.g. cimetidine, ranitidine, domperidone, cisapride
- Antivertigo drugs e.g. cinnarizine, flunarizine
- Anticonvulsants e.g. carbamazepine, phenytoin
- Antimalarials e.g. chloroquine, amodiaquine, hydroxychloroquine
- Antibiotics e.g. erythromycin
- Antihistamines e.g. diphenhydramine
- SHT antagonist e.g. sumatriptan
- Anxiolytics e.g. diazepam, buspirone
- Illicit drugs e.g. cocaine, ecstasy
In addition to drug-induced dystonia, arteriovenous malformation, cerebrovascular accident, cerebral tumour, encephalitis and spinocerebellar degeneration can all present with acute dystonia.
Clinical features
The clinical presentation of acute dystonia is variable. Examples of acute dystonias include:
- Oculogyric crisis
- Initial symptoms include agitation, restlessness, fatigue and fixed stare. This phase is followed by a more extreme and sustained spasm of extraorbital muscles resulting most commonly in upward deviation of the eyes. Additionally, the eyes may adduct.
- Buccolingual crisis
- Features of buccolingual crisis may include:
- Trismus (an inability to open the mouth normally)
- Risus sardonicus a highly-characteristic, abnormal sustained grimace
- Dysarthria (difficulties with articulation and speech)
- Dysphagia (difficulties with swallowing)
- Grimacing
- Tongue protrusion or sensation of the tongue feeling swollen
- Features of buccolingual crisis may include:
- Laryngospasm
- Laryngospasm presents as stridor, and although rare, is potentially life threatening.
- Trunk involvement
- Acute dystonia involving the trunk may result in the characteristic posture of opisthotonus.
Patients may also present with the consequences of acute dystonic episodes such as:
- Chipped teeth
- Temporomandibular joint (TMJ) dislocation
- Tongue lacerations
- Respiratory distress secondary to pharyngeal muscle involvement
Differential diagnosis
- Dislocated temporomandibular joint
- Hyperventilation
- Hypocalcaemia and hypomagnesaemia
- Primary neurological cause e.g. temporal lobe epilepsy, meningitis, stroke
- Tetanus
- Toxicity
Management
Acute dystonia is essentially a clinical diagnosis based on a careful history and characteristic clinical presentation.
Anticholinergic agents are the treatment of choice because they block cholinergic receptors and are thought to balance the cholinergic and dopaminergic activity: intravenous (IV) or intramuscular (IM) procyclidine 5-10mg or benztropine 1-2mg (IV/IM) are the drugs of choice. If symptoms are due to an acute dystonic reaction, there should be an improvement within 5 minutes of IV administration and 20 minutes if given IM. Patients would be expected to be symptom-free by 30 minutes. A second dose can be given if there has been no response after 10 minutes following IV administration (30 minutes for IM). However, if there continues to be no improvement, an alternative diagnosis and cause should be sought.
Benzodiazepines are GABA agonists; they inhibit and antagonise excitatory dopaminergic neurons. They can be helpful in refractory cases of dystonia (e.g. diazepam 2.5-10mg IV).
Prophylaxis is required for 48 to 72 hours to prevent recurrence of symptoms: oral procyclidine 5mg TDS is appropriate. In practice, patients are usually given prophylaxis for up to a week. Patients should receive advice about the potential for recurrence of dystonia if prophylaxis is not adhered to.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
