Mrs. McIntyre had been at home with Bo, her golden retriever, curled up at her feet when he suddenly stiffened up and started paddling furiously, almost as if he were trying to swim. He made strange sounds and lost control of his bladder. She called his name, but he didn’t respond. After about 30 seconds Bo relaxed and raised his head. A few seconds later he was a little unsteady and seemed a bit disoriented, but shortly after had returned to normal. Although she had never seen one, Mrs. McIntyre was sure Bo had just had a seizure.
At the hospital, Bo showed no sign that something had happened, and my examination didn’t reveal anything abnormal. Bo appeared to be a healthy three-year-old dog. Given these findings and the fact that the seizure had been followed by a period of disorientation (called a post-ictal period), I suspected that Bo had idiopathic epilepsy. Epilepsy is a term that applies to any seizure disorder. With idiopathic epilepsy, the brain is structurally normal but the exact mechanism behind the epilepsy is unknown.
Most patients with idiopathic epilepsy have their first seizure between six months and five years of age, so age of onset can help in arriving at the diagnosis. Even so, there’s no specific test for this disease, and it’s important to look for other causes of seizures before starting treatment. The first step is to look for diseases outside the brain, such as kidney or liver diseases. Blood and urine tests can help diagnose these diseases or rule them out; in addition, the information they provide is important in assessing the safety of anti-seizure medication. Chest and abdominal imaging are occasionally recommended to help evaluate internal organs as well.
If we can rule out these so-called extracranial causes, the next step is to consider diseases inside the brain. Tests to look for specific causes include analysis of cerebro-spinal fluid (a spinal tap) and brain imaging, either by MRI or CT scan.
If test results are normal, a presumptive diagnosis of idiopathic epilepsy is made. If a mild seizure like Bo’s was an isolated event, we might not start medication to control the seizures. Otherwise, providing medication is an option.
Fortunately, Bo’s laboratory tests were all normal; Bo’s working diagnosis was idiopathic epilepsy.
We didn’t start any medication at that time, but Mrs. McIntyre was to watch for further episodes. If she did witness another seizure, she was instructed to record it by writing a brief description of it and timing its duration. She would also note any events that might have triggered it. For example, was it immediately after eating? Was it at a time of high anxiety? Mrs. McIntyre was also advised to refrain from putting her hands near his head during an episode – taking care not to be bitten during involuntary jaw snapping and in the period of post-ictal disorientation that may follow a seizure.
Four weeks later Bo had another seizure, and I started him on medication. On medication, Bo did well. Since then, he has been in twice annually for a physical examination and monitoring of his mediation levels and liver function. In the six years since his first seizure, he has had one more seizure, but has otherwise been seizure-free.