Brain disorder discloses its presence with laughter

Researchers' report says uncontrolled giggles can signal congenital lesion

February 24, 2000|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

A baby's first laugh should bring only joy.

But for a tiny number of children, some early grins and giggles can signal a rare brain abnormality characterized by seizures and an unprovoked urge to burst out laughing.

It's caused by a congenital brain lesion called a hypothalamic hamartoma. And neurologists writing in this week's edition of Neurology, the journal of the American Academy of Neurology, say there's nothing funny about it.

The urges don't always produce laughter. And "many patients find the feeling pleasant," said Dr. Samuel Berkovic, of the University of Melbourne, Australia. "However, they are aware that sometimes a seizure may follow, and this is frightening."

One 25-year-old man described in the report has had giggle fits since infancy. At 14, he began having epileptic seizures, sometimes preceded by the urge to laugh.

Drugs controlled the seizures, but he is still coping with an urge to laugh up to 10 times a day. He learned as a child to bite his lip to suppress it, letting it out only when laughter was appropriate.

Berkovic wrote the article with Dr. Jonathan W. Sturm, also of the University of Melbourne, and Dr. Frederick Andermann, of McGill University in Montreal.

"This is not strictly speaking a tumor," Andermann said. A hamartoma is a collection of nerve cells that appears in the wrong place. Hypothalamic hamartomas are attached to the hypothalamus, a structure deep in the brain that regulates thirst, temperature, appetite and emotions.

The hypothalamus also plays a role in natural laughter, joined by other parts of the brain involved with thought, emotions and the muscles of the chest and throat.

The hamartomas don't grow, but they do generate electrical discharges that produce epileptic seizures. And hamartoma cells can eventually provoke epileptic discharges elsewhere in the brain.

Patients with larger hamartomas -- typically the size of a grape -- suffer unmanageable epileptic seizures, deteriorating mental abilities and behavioral problems.

"The only way to deal with these, if they're sufficiently bad, is to try to get them out," Andermann said. Surgery, by destroying the lesions with electricity or radiation, can provide "considerable" improvement.

But a rare minority of patients have tiny hamartomas, barely two-tenths of an inch in diameter, that produce only a milder form of epilepsy and the urge to laugh.

While these small lesions are too difficult for surgeons to approach, the seizures they cause are controllable with medication.

The impulse to laugh, however, is not. One 34-year-old woman, who had suffered from giggling attacks since she was 4, described the sensation as "a tickling inside my head." She gave up singing because the urge to laugh caused her voice to rise uncontrollably.

An 18-year-old high school student began 30-second episodes of facial and limb twitching at age 2, but no seizures. Her laughing attacks started at age 10, and recur as often as 15 times a day.

Andermann said it's not clear yet whether this pathological urge to laugh can be cured.

"We're still at the stage of trying to describe and recognize it," he said. "The next question is what else to do for this."

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