Regarding the Essential tremor , which of the following statements is incorrect?
ExplanationD. This patient’s history and examination, including her family history, are consistent with essential tremor (ET). ET is characterized by a bilateral (though sometimes asymmetric) postural tremor, typically 4 to 8 Hz with or without a kinetic component (a tremor occurring with action) that may involve the limbs, head, chin, lips, tongue, and even voice. A family history of tremor is present in the majority of patients with ET; ET exhibits an autosomal dominant pattern of inheritance with high penetrance. Although there is this strong familial component, a specific gene causing ET is yet to be identified (at the time of the publication of this book), though an association with a single nucleotide polymorphism in the LINGO1 gene has been demonstrated. The tremor of ET classically improves with alcohol intake. Similar to most movement disorders, it does not continue in sleep (though there are exceptions. Enhanced physiologic tremor is one of the most common causes of postural tremor, but rarely causes enough disability to require treatment. It is faster than ET, 7 to 12 Hz. Both ET and enhanced physiologic tremor increase with anxiety, but in enhanced physiologic tremor, the frequency is variable and can be slowed by mass loading (increasing weight on the arm). The presence of family history also makes ET more likely than enhanced physiologic tremor. There is no mention of abnormal posturing to suggest this patient has dystonia with secondary tremor (dystonic tremor). Task-specific tremor is a tremor only occurring, as the name implies, with specific tasks, such as writing or playing of musical instruments. There is no such history presented in the case. Another type of tremor is rubral tremor, also known as Holmes tremor, which is a relatively low-frequency tremor typically present at rest, with posture, and with action. It results from lesions in the dentate nucleus of the cerebellum and/or the superior cerebellar peduncle, and is often seen in patients with multiple sclerosis. First line agents for the treatment of ET include the β-blocker propranolol and primidone (an anticonvulsant which is converted into phenylethylmalonamide [PEMA] and phenobarbital). Other treatments that have less evidence to support their use include other β-blockers such as atenolol, the antiepileptic agents topiramate and gabapentin, and benzodiazepines including clonazepam. Often, combinations of these therapies are necessary. In pharmacotherapy-resistant cases in which the tremor is disabling, deep brain stimulation to the ventral intermediate nucleus of the thalamus can be effective. Although ethanol intake does improve the tremor in ET, it is not an appropriate long-term therapy. Levodopa is not an effective therapy for ET. For the patient depicted in question 98 topiramate is likely the best option, as propranolol will exacerbate her asthma, and given her occupation, a sedating medication such as clonazepam would be relatively contraindicated.
