(Updated with Answer) The Medical Challenge: The Case of the Girl Who Laughed Too Much

The “Medical Challenge” is a new column by Dr. Rohan Ramakrishna. The cases described are based on real patients. Please leave your thoughts on this case in the comments, and check the comments again next week to learn the real explanation.

Julie laughs a lot. At six years old, she has always been regarded as the most cheerful among her two other siblings. Recently, however, Julie’s mother Sarah has noticed that her daughter seems to laugh for no reason approximately three-to-four times a day. These episodes of laughter last only seconds and follow seemingly banal periods devoid of humor. When asked about what makes her laugh, Julie reports not remembering.

A few months go by and Sarah notices that these laughing spells not only persist but seem to increase in frequency. Then Julie’s teacher calls a parent-teacher conference to discuss Julie’s increasingly aggressive behavior towards her peers and teachers at school. Julie subsequently received a firm scolding from her parents and was told to “behave.” Julie, of course, denied culpability and insisted she had done nothing wrong. She was subsequently grounded.

Three months later, Julie’s laughing fits and aggressive behavior have not subsided. Sarah is confused and worried. She decides to visit her pediatrician.

Sarah sits anxiously in her pediatrician’s office as she watches Dr. Ray examine Julie. Julie answers all his questions appropriately but has two laughing fits during her physical exam. Dr. Ray recognizes that these episodes are out of place. Dr. Ray also notices that Julie’s hands seem bigger than would be appropriate for her age. He orders an X-ray of her hands, which reveals a bone age of 10, well above her actual age of 6. Dr. Ray now believes he has an important clue.

If you were Julie’s pediatrician, what would you do next? What might explain her strange symptoms?

Answer

An astute pediatrician, Dr. Ray suspects precocious puberty and diagnoses this entity through his physical exam and bone x ray showing advanced bone growth. In
addition, Dr. Ray recognizes Julie’s laughing fits as inappropriate and suspects these episodes require further evaluation. As a next step, he orders an MRI(Magnetic
Resonance Imaging) to evaluate the brain as most causes of precocious puberty originate from central sources(ie brain) rather than peripheral sources(ie glands).

Julie’s MRI is nothing short of surprising.

In the nearby graphic(courtesy Barrow Neurological Institute), the arrow indicates a lesion in the hypothalamus of the brain. The hypothalamus is one of the master regulators in the body. Its functions are diverse and include regulation of hormonal, behavioral, and homeostatic functions. In short, it is like a car computer that makes sure all the different parts
are efficiently coordinated and working appropriately. In Julie’s case, her MRI demonstrates a lesion known as a hypothalamic hamartoma.

Hypothalamic hamartomas are benign tumors that are classically known to cause gelastic seizures. Gelastic(from the greek “gelos” – to laugh) seizures are seizures characterized by mechanical bursts of laughing without antecedent environmental cues or an internal feeling of humor. These hamartomas are seizure inducing and the seizures they induce are often characterized by these aforementioned laughing fits. In addition, these seizures can be associated with disorders in personality manifesting as increasing aggression among other unpleasant personality traits. Moreover, either as a result of the tumor or the seizures themselves(likely a combination of both), people afflicted with this condition can have worsening cognitive performance and memory decline. Finally, these seizures tend to evolve with time sometimes turning into generalized seizures characterized by the unconscious stiff shaking with which most people are familiar.

Because of the tumor’s location in the hypothalamus, it can disrupt normalendocrine function. In Julie’s case, it caused an abnormal release in hormones related to sexual maturation leading to her increased growth and precocious puberty. Sometimes this can be effectively treated with medicines that effectively discourage release of these hormones.

In terms of treatment, Julie has essentially two options. The first is to treat with anti- seizure medicines to determine whether or not her symptoms improve. The second
involves neurosurgery wherein the tumor is carefully removed. In addition to the usual risks of any medical procedure, the risks of surgery here involve permanent memory deficits and potentially permanent disruption of endocrine function requiring lifetime hormone replacement therapy. In experienced hands, however, surgery is a safe and effective therapy that can drastically improve the quality of life in patients with these tumors. As with every patient, though, a careful discussion of the risks and benefits of various treatment options needs to be properly undertaken prior to any treatment decisions.

Finally, it is important to note that hypothalamic hamartomas are extremely rare entities with guestimates placing their prevalence at 1 in a million. So next time you laugh, there’s no need to worry.

Photo by peyri

Comments