A paroxystic event is a non-specific term used to define an abnormal event of the body with an abrupt onset and an equally sudden return to normal. A paroxystic event can relate to a problem in the nervous system (epileptic seizure, narcolepsy/cataplexy, acute balance loss, acute muscle stiffness or weakness, 'movement disorder') or a disease in other organs (heart disease causing syncope, acute weakness and tremor caused by low blood sugar level). Epileptic seizures are the most common and certainly best understood type of paroxystic event in veterinary neurology.

How do you investigate paroxystic events?
In the large majority of cases, your veterinarian has not witnessed these paroxystic events and very often will not to detect anything wrong on examination of your animal. Giving a detailed description of these events is therefore fundamental. This should include the following information:

• When was the first event witnessed
• How many events your animal had in the past
• Did all these events look the same
• What was your animal doing just before these events
• Can you trigger or predict one of these events
• How long each event last
• Was your animal conscious or unaware of its surrounding
• Was your animal able to follow your movement with its eyes or did its eyes looked glazed or were flickering
• Was your animal stiff, weak, twitching, paddling, violently shaking or not moving at all during the event
• Did you animal foam from its mouth, urinate or defecate
• Did its tongue or gum look pale, blue or pink
• Will you consider your animal normal in between each events

Answers to these questions may help your veterinarian to determine if these paroxystic events are related to a neurological problem or not and decide on further tests. Obtaining a video footage of these events While some paroxystic events can be the symptom of disease such as a stroke, a tumour or an inflammation, others can be caused by chemical unbalance or abnormal wiring in the nervous system and therefore may not show up on any test.

One of the best examples is primary epilepsy (also known as idiopathic epilepsy) which diagnosis is made by first recognising the paroxystic events as being an epileptic seizures and then ruling out diseases that could underlie them. Other paroxystic events suspected to be related to a chemical unbalance or abnormal neuronal wiring include events such as head bobbing, paroxystic dystonia, collapsing Cavalier, primary orthostatic tremors, Scottie cramps, narcolepsy/cataplexy or some behavioural disorder such as compulsive/obsessive disorder.

What to do if all tests come back as negative?
Unless the wrong part of the body has been looked at, tests may come back as negative when investigating many paroxystic events. Response to drug therapy can be used to indirectly diagnose certain condition. Simply observing a reduction in the frequency and severity of these events does this while the animal is treated with a particular type of drug (e.g. suspected narcolepsy/cataplexy if the animal appears to respond to anti-narcoleptic drug).

More than one drug may need to be used and for a sufficient length of time before to draw any conclusion on the nature of the event. Having a good idea of the frequency of these events prior to treatment is also very important to assess response to treatment. If these events are occurring very infrequently, your veterinarian may decide not to start your animal on any therapeutic trial and just monitor the frequency.

If you are concerned about the health of your pet you should contact your veterinary surgeon.