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Posterior Fossa Syndrome

What is posterior fossa syndrome?

Posterior fossa syndrome is also called cerebellar mutism syndrome. Children with posterior fossa syndrome may have problems with communication, motor skills, and mood. This syndrome sometimes develops after surgery to remove a brain tumor in the posterior fossa.  

The posterior fossa is a space near the back of the base of the skull. It contains the cerebellum and brainstem.

Tumors in the posterior fossa region account for over half of all brain tumors in children. About 25% of children who have surgery to remove medulloblastoma, a posterior fossa tumor, will develop posterior fossa syndrome.

Tumors in the posterior fossa region account for over half of all brain tumors in children. About 25% of children who have surgery to remove medulloblastoma, a posterior fossa tumor, will develop posterior fossa syndrome.

Risk factors for posterior fossa syndrome

Posterior fossa syndrome can happen after surgery to remove a brain tumor within the posterior fossa. 

About half of all children’s brain tumors are in the posterior fossa. Medulloblastoma occurs in this part of the brain. It is the most common malignant brain tumor in children. About 25% of children who have surgery to remove medulloblastoma will develop posterior fossa syndrome. 

But posterior fossa syndrome also can happen after surgery to remove other kinds of brain tumors in the posterior fossa. Those include astrocytoma and ependymoma.

Doctors do not know exactly why this condition affects some children and not others. The risk of posterior fossa syndrome is higher for children who are younger. This syndrome is also likely to occur when a child’s brain tumor:

  • Is located between the two halves of the cerebellum
  • Involves both halves of the cerebellum, especially important structures deep within both halves
  • Is large 
  • Extends into the brainstem 
  • Is a non-SHH subtype medulloblastoma
  • Is removed by a surgeon who does not perform many brain tumor procedures

Symptoms of posterior fossa syndrome

Children with posterior fossa syndrome display 3 main types of symptoms:

  • Speech and communication difficulties
  • Problems with muscle control and coordination
  • Mood changes

Speech and communication difficulties

Some children lose the ability to speak, also known as mutism. Other children can say a few words or speak only using short phrases.

Most children’s speech returns over the next few days or weeks. But some continue to have limited speech for months. Your child’s speech can sound different than it did before surgery.

Your child’s speech may improve over time. But some speech difficulties may not fully resolve.

  1. Dysarthria

    Many children with posterior fossa syndrome have speech problems due to muscle weakness or poor muscle control. Their speech may sound slurred or garbled. This is because of trouble controlling muscles in the mouth, tongue, and palate.

    Your child may have changes in their rate or speed of speech:

    • Slowed rate – Your child may say words or parts of words at a slower than usual rate.
    • Gaited, scanning, or metered rate – Your child may say one syllable at a time. The space between syllables may be similar in length to the space between words. This can make it difficult for a listener to know where a word ends, and the next word begins. That can make speech hard to understand.

    Your child may have changes in the volume or loudness of speech:

    • Speech may be softer than usual.
    • The volume of your child’s speech might vary. Some words or parts of words may be softer than usual. Others could suddenly be louder than usual.

    Your child may have changes in intonation (changing pitch) or prosody (stress and intonation) of speech:

    • Your child’s speech might be high-pitched.
    • Limited prosody – You may notice a lack of or limited change in inflection when speaking. Prosody is the pattern of stress and intonation in a language. Prosody can change the meaning of a sentence or convey emotion.

  2. Apraxia

    Your child may have speech problems caused by damage to brain pathways that control the ability to complete familiar movements. This can include movements needed for speech and other movements. Your child may have trouble saying what they want to say. They may mouth words instead of saying them because they have trouble supporting breathing at the same time for speech.

    Your child may be able to make some movements with their mouth as a reflex. But they may not be able to make similar movements with their mouth on command. They may mouth words instead of saying them because they have trouble coordinating their voice and breath at the same time for speech. They may also have trouble with the movements needed for feeding and swallowing.

    Learn about speech therapy

Problems with muscle control and coordination

Posterior fossa syndrome causes motor issues. These are the result of injury to the cerebellum. 

A child with posterior fossa syndrome will have problems coordinating movements. This is known as ataxia. A child with ataxia will have trouble with large movements and/or fine motor skills such as: 

  • Sitting without support or help 
  • Walking in a steady way 
  • Balancing when standing on 2 feet or 1 
  • Using utensils while eating or using a pencil or pen to write or draw 
  • Manipulating small objects in their hands  

Your child could have other motor difficulties including:

  • Combining parts of motor tasks into a smooth, coordinated process.
    • Your child’s motor processes may look choppy or uncoordinated.
    • Tasks that have many parts may be slow and take a lot of effort. A child may have trouble doing 2 parts of a process at the same time.
  • Apraxia that affects other motor movements. At first, some children may have a tough time moving when you ask them to move. Some children may be able to make some body movements as a reflex. But they may not be able to make similar body movements on command. For example, they may scratch their nose when it itches but not touch their nose when asked to do so.
  • Difficulty reaching for or pointing to an item (dysmetria). This can cause someone to miss what they are trying to reach. They might be too short in how they reach. Or they might reach past what they are trying to reach. Dysmetria can affect the arms or the legs.

Mood changes

Children with posterior fossa syndrome often have problems controlling or expressing emotions.

They may show responses that are too exaggerated for the situation. They may be very irritable or agitated and cry often. But extra giddiness with unusual amounts of laughter can happen, too.

Children may have mood swings, or they may be difficult to calm. Your child may show little or muted response to things around them. This is often referred to as flat affect.

Mood changes may get in the way of your child’s ability or desire to take part in daily activities.

Learn about psychology

Course and recovery for posterior fossa syndrome

Symptoms of posterior fossa syndrome usually begin within 1–2 days after surgery. But symptoms always start within the first week after surgery.

Symptoms of posterior fossa syndrome range from mild to severe. Most children gradually improve and regain the ability to speak again. Most children will regain the ability to walk on their own. But some difficulties with speech, motor skills, and/or mood may last longer—even years.

If your child’s speech, motor, and mood symptoms begin to improve in the first week after posterior fossa syndrome begins, it is less likely they will have problems that require long-term help. It is more likely your child will continue to have problems that require help if it takes longer to show signs of improvement.

Therapies such as speech therapy can help to improve speech and swallowing difficulties.

Physical and occupational therapy can use motivating activities and exercise to improve your child’s ability to take part in self-care activities, to move, and to play on their own.

Working with a psychologist can help your child better manage moods and emotions. A neuropsychologist can work with your child to improve their thinking skills, such as:

  • Attention
  • Memory
  • Orientation
  • Cognitive communication
  • Visual reasoning skills

Posterior fossa syndrome and cognitive effects

Cognitive effects (issues with memory, attention, and decision making) are not used to diagnose posterior fossa syndrome. But they are common in children who have it.

Children with posterior fossa syndrome often have more problems with thinking skills and academic abilities. Some of these difficulties can take place as soon as 1 year after the brain tumor diagnosis. Other difficulties become more noticeable years later.

Your child may:

  • Perform tasks more slowly
  • Have trouble paying attention
  • Have issues organizing and planning
  • Be less able to problem-solve and communicate ideas

These difficulties are likely to persist to some degree. 

Some children who have had posterior fossa syndrome will benefit from having formal academic accommodations in school. 

Doctors may suggest a neuropsychological assessment (a test that can help measure attention, memory, language skills, decision making, and more). It can help identify patterns of strengths and weaknesses in a person’s thinking and academic skills. It can be used to recommend accommodations and modifications. 

Learn about cognitive late effects

Key points about posterior fossa syndrome

  • Posterior fossa syndrome is sometimes called cerebellar mutism syndrome.
  • Posterior fossa syndrome symptoms include problems with communication, motor skills, and mood.
  • Posterior fossa syndrome sometimes develops after surgery to remove a brain tumor in the posterior fossa (the space near the back of the base of the skull).
  • Symptoms of posterior fossa syndrome usually begin 1–2 days after surgery.
  • If your child’s symptoms begin to improve in the first week after posterior fossa syndrome begins, it is less likely they will have problems with memory and language that require long-term help.
  • It is more likely your child will continue to have problems if it takes longer to show signs of improvement.
  • Academic accommodations are available for children with posterior fossa syndrome.

—
Reviewed: April 2023

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