Hypothalamic Hamartoma

What is a hypothalamic hamartoma?

A hypothalamic hamartoma (HH) is a rare, present-at-birth growth on your hypothalamus. The hypothalamus is an almond-sized structure deep within your brain. It links your endocrine system and your nervous system to maintain homeostasis, or a state of balance, for your body systems to function as expected.

The growth is a noncancerous tumor. It can disrupt many important functions of the hypothalamus, including:

• Blood pressure
• Body temperature
• Feelings of stress
• Hunger and thirst
• Release of hormones from your pituitary gland
• Sleep and wake cycles

A hypothalamic hamartoma forms while a fetus develops. It grows as your brain grows. HH doesn’t spread to other parts of your brain or body. It usually involves one lesion, but in some cases, there are several.

Treatment options are available to manage symptoms of HH.

What are the symptoms of hypothalamic hamartoma?

The symptoms of hypothalamic hamartoma vary for each person but may include:

• Precocious (early) puberty
• Seizures
• Neurological symptoms

Precocious puberty (early puberty)

Central precocious puberty happens when your brain releases sex hormones too soon. This typically happens before age 8 in children assigned female at birth (AFAB) and before age 9 in children assigned male at birth (AMAB).

Physical signs for children AFAB include:

• Breast development
• Pubic and underarm hair growth
• Menstrual bleeding
• Acne

Physical signs for children AMAB include:

• Deepening voice
• Facial, underarm and pubic hair
• Penis and testicle enlargement
• Acne

Seizures

Seizures are common with this condition. One of the most frequent types is a gelastic seizure. This brief episode may only last a few seconds but can happen multiple times per day, even per hour in severe cases.

A gelastic seizure causes you to burst into an uncontrollable fit of laughter when there’s abnormal electrical activity happening in your brain. These seizures usually begin before your child’s first birthday. They reduce in frequency after age 10.

You may experience other seizure types like:

• Atonic seizures, or drop attacks, which cause a sudden loss of muscle control
• Dacrystic seizures, or short bursts of uncontrollable crying
• Tonic-clonic seizures, which cause a loss of consciousness and uncontrollable body movements

Neurological symptoms

HH may affect your behavior, mood and cognitive function, including:

• Attention-deficit/hyperactivity disorder (ADHD)
• Conduct disorder
• Intellectual disability
• Mood disorders
• Oppositional-defiant disorder
• Reactive behavior (aggression, anger)
• Short-term memory problems

What are the types of hypothalamic hamartomas?

The two types of hypothalamic hamartomas are based on the location and the symptoms they cause:

• Intrahypothalamic lesion. A growth is near the back of your hypothalamus. It may disrupt electrical activity in your brain and cause seizures and abnormal behavior.
• Parahypothalamic lesion (pedunculated lesion). A growth is near the front of your hypothalamus. It may cause early puberty.

It’s possible to have both types at the same time.

What causes hypothalamic hamartoma?

Experts don’t know exactly what causes HH and there’s no known way to prevent it. The majority of cases happen randomly. This means that they don’t usually run in your biological family history, so you likely won’t inherit it.

Recent studies of removed tumor tissue found a somatic variant within the tumor of the GLI3 gene. Other genetic variants have also been found in removed tumor tissue. Research is ongoing to learn more about the possible genetics involved.

There may be a link between hypothalamic hamartoma and a genetic condition called Pallister-Hall syndrome (PHS). This condition is the result of a genetic variant that can cause abnormalities in how your hands, feet, larynx (voice box) and anus develop.

What are the risk factors for hypothalamic hamartoma?

Anyone can develop this condition. It’s slightly more common in people assigned male at birth than people assigned female at birth. HH primarily affects children and adolescents. But in some cases, you might not receive a diagnosis until symptoms appear in adulthood.

What are the complications of hypothalamic hamartoma?

Early puberty can affect a child’s physical and mental health if their body is changing faster than their peers. It may result in short stature, for example. In addition, your child may not fully understand the changes that are taking place, which may affect their self-esteem and emotional well-being. Your child’s care team can help them manage any possible complications that may arise.

How is hypothalamic hamartoma diagnosed?

Your provider will offer imaging tests to diagnose HH. An MRI creates highly detailed images of your brain. Children usually need light sedation so they stay still during an MRI. If they move, the images might not be clear.

Your provider may also recommend an electroencephalogram (EEG) if you have seizures. This test monitors the electrical activity in your brain.

Neurological testing can measure the extent of cognitive problems, such as thinking, learning and remembering. Your provider may also recommend blood tests to check hormone levels. These tests may help guide treatment.

HH may be difficult to diagnose because symptoms may resemble other neurological conditions.

How is hypothalamic hamartoma treated?

Treatment for HH may include:

• Medications (gonadotropin-releasing hormone agonists) for precocious puberty
• Surgery to manage seizures

Your child’s provider may recommend other treatment options like educational support in school and therapy or medications for different types of mood, behavioral and psychological disorders.

Hypothalamic hamartoma surgery

A provider may recommend epilepsy surgery or another procedure to remove or destroy the hamartoma and manage seizures. Antiseizure medications usually don’t work well to treat gelastic seizures but may help manage other seizure types.

Common procedure types may include:

• Gamma Knife surgery. This treatment is a form of radiation therapy and it doesn’t require an incision (cut). It uses powerful beams of energy to destroy the tumor.
• Resection (removal surgery). A surgeon may perform brain surgery (craniotomy) to open your skull, or they drill a hole in your skull and insert an endoscope (a small tool) to remove the growth.
• Stereotactic laser ablation. This minimally invasive option destroys the tumor using a laser light that’s delivered through a fiber optic cable.
• Stereotactic thermoablation. This form of ablation therapy uses heat to treat the hamartoma. A surgeon inserts thin probes through your skull until they reach the growth. They use radio waves to heat the probes and destroy the tissue.

What’s the prognosis for hypothalamic hamartoma?

The prognosis (outlook) is usually good for hypothalamic hamartoma because treatment options are effective at managing symptoms.

Surgery may reduce the frequency or severity of seizures. Some people are seizure-free after surgery. In some cases, surgically removing the hamartoma may cure the condition if it can be done safely. But there’s a risk that seizures may return.

Monthly injections of a drug that suppresses the release of certain hormones help keep early puberty symptoms in check. Your child’s provider may stop the medication when they reach the normal age for puberty to occur. Most children and teens have an expected puberty and sexual development at this time.

Your child’s provider can give you the best information on what you can expect for your situation.

What is the survival rate for hypothalamic hamartoma?

A healthcare provider will let you know what your life expectancy may look like, as this can vary from person to person and depend on many factors, including:

• The size and type of hamartoma
• The severity and frequency of seizures
• The effectiveness of treatment

There’s a risk of sudden unexpected death in epilepsy (SUDEP) with hypothalamic hamartomas. A provider will help you stay safe and create a treatment plan to manage seizures.

When should my child see a healthcare provider?

If you suspect something is wrong, you know your child best, so don’t hesitate to contact a healthcare provider. Look out for signs or symptoms that affect their behavior, cognitive function and hormone regulation, which may include:

• Seizures
• Early puberty (like early hair growth or voice changes)
• Changes in concentration, memory or learning
• Behavioral changes (like anger or frustration over small things)
• Hormone imbalances (like extreme thirst, appetite changes or mood swings)

What questions should I ask my child’s healthcare provider?

If your child has HH, you may want to ask their provider:

• What type of treatment do you recommend?
• How likely is it that they’ll need multiple treatments or surgeries?
• What are the side effects of treatment?
• How will treatment affect my child’s ability to work, go to school and perform normal activities?