Tuesday, February 23, 2016

Orthostatic tremor - pearls

Hassan A, Ahlskog AE, Matsumotos JY.  Orthostatic tremor: clinical, electrophysiologic and treatment findings in 184 patients.  Neurology 2016; 86: 458-464.

The article is a Mayo series of 184 patients seen over 37 years. 

Definition: lower body tremor activated on standing, absent when seated or lying, improved by walking or leaning.  Patients report leg shaking, unsteadiness and imbalance.  Electrophysiologic findings are unique:  a 13-18 hz tremor of lower limbs or trunk. 

Demographics:  64 percent were female, mean age 59 years, (range 13-88) .  One hundred percent reported symptoms only when standing and absent while seated.  Descriptions included "imbalance, unsteadiness, weakness, 'funny feeling,' 'jelly legs,' leg tightness, pain, tremor, shakiness, or quivering.  Sixty percent of cases included the arms.  24 percent had falls.  28 percent had other types of tremors included ET, which could be associated with a response to alcohol.  Other associated tremors included head tremor  (1), handwriting tremor (2), functional (1), jaw tremor (1).  Forty percent had other neurologic diseases including Parkinson's and many others, degenerative or otherwise.  Nine patients had a family history of orthostatic tremor. 

Medication responsiveness occurred in 139 patients.  Sixty seven percent of medications prescribed did not demonstrate benefit.  The most efficacious was benzodiazepines, especially clonazepam, with 48 percent of patients so treated showing moderate or marked benefit.  Thirty three percent of patients given gabapentin showed mild or moderate benefit, with lower responses to valproate, primidone, levodopa (only 1/33 responding), and no benefit from anxiolytics or antidepressants.  The responsiveness to clonazepam diminished over time , and of those only a few, 16 got benefit from another drug, including gabapentin, valproic acid, propranolol, pramipexole, bromazepam, primidone, carbi-levodopa, and pregabalin.  Three patients underwent DBS and improved.

There was a high personal anf family history of PD (8.9 and 10.7 percent). 

EMG is easy and pathognomonic.  MRI's often show various types of white matter disease and occasional meningiomas.

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