Page 803 - Clinical Small Animal Internal Medicine

70 Seizures and Movement Disorders 771

VetBooks.ir Abnormal Involuntary Movement
History:
Verbal or Video

HYPERKINETIC HYPOKINETIC PAROXYSMAL

No Tremor Tremor Evaluate for recent Consider epileptic seizure
drug exposure

Myotonia or Paresis No Paresis
fasciculations

Metabolic evaluation
EMG and NCV testing Consider Multifocal Consider Cerebellar
Consider muscle/nerve biopsy or noncerebellar disease Disease
Variable extensor muscle rigidity:
Tetany Metabolic evaluation Acute onset Progressive onset

Evaluate for toxicity
Metabolic evaluation
Endocrine function testing Metabolic evaluation Metabolic evaluation
Diet evaluation MRI scan and/or CSF analysis
Evaluate for toxicity MRI scan of brain
Constant extensor muscle rigidity:
Tetanus
Yes: Treat
If normal: CSF analysis
Metabolic evaluation
Evaluate for wounds No: CSF Analysis
Consider CSF analysis
Normal:
Consider MRI scan
Figure 70.2 Diagnostic paradigm for hyperkinetic movement disorders.

weakness with falling from incoordination. A reliable Treatment
test is to hop an animal on each leg individually to see if The goal for the control of tremors in small animals is
it will collapse on that leg during testing. A weak animal to determine the etiology, remove any inciting cause
will not be able to support weight on that limb, while an (toxin or iatrogenic), and provide immediate and
uncoordinated one will. If paresis is present, then one prolonged symptomatic relief for acquired diseases.
should consider either a multifocal or noncerebellar cen- A number of treatments for essential tremor have
tral nervous system disease. A history of possible toxicity been proposed for people, with varying results. First‐
exposure should be ruled out prior to pursuing more line treatments useful in the dog include phenobarbi-
advanced testing. If the metabolic evaluation is normal tal at 2.5 mg/kg PO BID, or a beta‐adrenergic
as stated above, then a MRI scan of the brain and/or spi- antagonist (propranolol 2.5–10 mg PO BID to TID).
nal cord with possible cerebrospinal fluid (CSF) analysis Benzodiaze pines appear not be effective in humans or
is warranted to evaluate for the underlying etiology. dogs (personal experience). Topiramate, has recently
If paresis is not present with the tremor syndrome,
then it is most likely that the animal is suffering from a been shown to be efficacious in refractory essential
tremor cases in humans at a dose range of 100–200
pure cerebellar disease process. Acute onset of clinical mg/day.
signs is now more suggestive of either a toxic reaction or Recommended emergency treatment for acute onset
inflammatory disease process. If toxicity is documented, of suspected acquired tremor disease should be based
then no further diagnostic testing may be needed, and on an IV loading dose of diazepam or midazolam at 0.5
symptomatic therapy can be instituted. If toxicity cannot mg/kg IV followed by constant‐rate infusion (CRI) of
be documented, then a CSF analysis is recommended. If either drug at 0.5 mg/kg/h in 0.9% saline at 1.5 times the
the CSF is normal, then MRI scanning of the brain may maintenance fluid rate. This situation can be life‐threat-
be necessary. If the disease process is more chronic and ening and requires a rapid therapeutic approach.
progressive in nature, then the patient should be evalu- Adjuvant therapy to stabilize hyperthermia should be
ated for a possible mass lesion of the cerebellum with an given.
MRI scan prior to collection of CSF for analysis.