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Posterior Fossa Syndrome

Also known as: Cerebellar mutism, Cerebellar mutism syndrome, Cerebellar cognitive affective syndrome, Transient cerebellar mutism, Mutism and subsequent dysarthria

What is Posterior Fossa Syndrome?

Posterior fossa syndrome, or cerebellar mutism, is a condition that sometimes develops after surgery to remove a brain tumor in the posterior fossa region of the brain. The posterior fossa is a space near the base of the skull that contains the cerebellum and brain stem.

Children with posterior fossa syndrome usually have a collection of symptoms. The most prominent symptom is limited or loss of speech. Although children lack expressive speech, they may be able to process and understand information. Other symptoms of posterior fossa syndrome include changes in speech, movement, emotions, and behavior.

Symptoms usually appear 1-10 days after tumor surgery and can last weeks or months. Even with improvement, patients may have some degree of ongoing problems.

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.

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. Less commonly, surgery for other tumors, such as astrocytoma and ependymoma, may also cause posterior fossa syndrome.

Posterior fossa syndrome is not completely understood. Doctors don’t know exactly why this condition affects some children and not others. Although certain factors may increase the risk, posterior fossa syndrome cannot be predicted ahead of time. There is no known cure for posterior fossa syndrome, and the course of recovery varies widely.

Posterior fossa syndrome (also called cerebellar mutism) develops in about 25% of children who have surgery to remove medulloblastoma, a posterior fossa tumor. In this image, a young medulloblastoma patient plays a game with blocks.

Posterior fossa syndrome develops in about 25% of children who have surgery to remove medulloblastoma, a posterior fossa tumor.

Symptoms of posterior fossa syndrome range from mild to severe. Symptoms usually improve with time as the brain heals. Most children will regain the ability to communicate and walk independently. Recovery is usually a long process, occurring over weeks, months, or even years. Patients often have long-term problems in one or more areas of function, particularly gait, coordination, clarity of speech, and cognition. Children with more severe symptoms are more likely to have lasting deficits.

Care for posterior fossa syndrome usually includes a combination of rehabilitation services including physical therapy, occupational therapy, and speech therapy. Nutrition support, psychology, and school support are also important.

Common Symptoms of Posterior Fossa Syndrome

  • Loss of speech or mutism
  • Lack of muscle control or coordination
  • Abnormal eye movements
  • Emotional lability, irritability, or behavior changes
  • Trouble swallowing
  • Muscle weakness or low muscle tone
  • Temporary loss of voluntary movements
  • Cognitive problems

Symptoms of Posterior Fossa Syndrome

Posterior fossa syndrome is a collection of symptoms which include changes in speech, movement, emotions, behavior, and/or cognition.

    • Loss of speech (mutism): Some children completely lose the ability to speak. Other children are able to say a few words or speak very short phrases. This loss of speech usually occurs 1-2 days after surgery. For most children, speech returns over the next few weeks or months, but there may be some lasting speech impairments. Because this is a key feature of the condition, posterior fossa syndrome is also known as cerebellar mutism.
    • Speech problems due to muscle weakness or poor muscle control (dysarthria): Many children with posterior fossa syndrome have speech problems because they have trouble controlling the muscles of the mouth, tongue, palate, and vocal cords. Speech may be hard to understand due to slow rate of speech, slurred speech, trouble producing sounds, or problems with loudness, tone, or pitch.
    • Speech problems due to damage to brain pathways that control movements needed for speech (apraxia): Some children have trouble saying what they want to say correctly. They may have problems coordinating mouth movements for speech or saying target sounds or words consistently. They may also have difficulty moving their mouths voluntarily. For example, children may not be able to open their mouth or smile on command. However, they may yawn as a reflex or smile while laughing.
    • Trouble swallowing (dysphagia): Children may not be able to control the muscles used to swallow. This may require a change in diet, use of specialized equipment or strategies, or even tube feeding until problems improve.

    Learn About Speech Therapy

    • Lack of voluntary movements (apraxia): At first, most children will have a hard time moving when they are asked to (voluntary movements). However, they may display involuntary or automatic movements, such as yawning or grimacing. This may make arms and legs seem weaker than they are. Problems with muscle coordination become apparent only once apraxia improves and voluntary movements return.
    • Problems controlling movements (ataxia): A variety of problems in movement, balance, and muscle coordination are seen in posterior fossa syndrome. Children may have trouble with large movements as well as fine motor skills. Reduced hand eye coordination, trouble handling small objects, and unsteady walking become apparent as the child improves. Some degree of these problems will persist in most children with posterior fossa syndrome. During the early stages of posterior fossa syndrome, bowel and bladder control are impaired in most children, although these functions usually improve in time.
    • Weakness on one side of the body (hemiparesis): Some children may have weakness of one or both sides of the body.
    • Change in muscle tone (hypotonia or hypertonia): Muscle tone refers to the balance of muscle tension when a muscle is at rest. Hypotonia, or low muscle tone, can result in “floppy” muscles and the inability to control posture or sit upright. Hypertonia, or increased muscle tone, causes muscles to be too tight.
    • Involuntary movements: Some children may develop involuntary movements. These may include tremor, sudden muscle or limb jerks, or involuntary eye movements.
    • Problems with cranial nerves (cranial nerve palsies): Cranial nerves VI and VII are often involved in posterior fossa syndrome. The sixth cranial nerve controls eye movement. Problems with this nerve may cause double vision and the eye to be “crossed.” The seventh cranial nerve is the facial nerve. Damage to this nerve may cause the face to “droop.” Children may drool or have problems making facial expressions.

    Learn About Physical Therapy

    Learn About Occupational Therapy

  1. Children with posterior fossa syndrome often have emotional lability. They may show responses, such as laughing or crying, that are unexpected or don’t match the situation. Children may have mood swings or be difficult to calm. Sometimes, children may appear withdrawn or show little response. Irritability, depression, anxiety, and inattention are also common. Sleep problems, including change in sleep patterns or schedule, may also occur.

    Some children with posterior fossa syndrome have changes in how they respond to sensations like touch, light, sounds, or movements. They may be bothered by things in the environment that did not cause a reaction before.

    These changes may limit a child’s ability or desire to participate in play, daily activities, or rehabilitation.

    Learn About Psychology

  2. Children with posterior fossa syndrome often show a decrease in cognitive function, including problems with focus, attention, processing speed, and memory. They may perform tasks more slowly and have trouble organizing and planning. Children may be less able to problem-solve and communicate their ideas. Decreases in cognitive function are likely to persist to some degree. However, it can be hard to know whether the cause is posterior fossa syndrome or if symptoms are due to cognitive late effects related to the tumor or treatment.

    Learn About Cognitive Late Effects

Symptoms of posterior fossa syndrome are complex, and they are often related to one another. For example, children may become agitated and frustrated when they are unable to communicate. Speech and language impairments may have several causes, including muscle weakness, apraxia, and cognitive impairment. In addition, patients continue to receive cancer treatments that may cause additional problems, make symptoms worse, or delay recovery. However, it is important to know that most patients do have significant improvement in symptoms over time and become independent in activities of daily living.

Good supportive care and encouragement can help promote the best recovery possible.

Risk Factors and Causes of Posterior Fossa Syndrome

Any child who has surgery to remove a posterior fossa tumor is at risk for posterior fossa syndrome. More research is needed to understand how and why the syndrome occurs.

The strongest risk factors for posterior fossa syndrome after surgery include:

  • Diagnosis of medulloblastoma
  • Midline position of the tumor
  • Involvement of the brainstem

Some research suggests that younger age, larger tumor size, hydrocephalus, or language difficulties before surgery may increase risk. However, research findings have been inconsistent.

Researchers are actively studying causes, symptoms, care, and outcomes. Injury to the nerve pathways that travel back and forth from the cerebellum to the cerebral cortex (dentate nucleus and superior cerebellar peduncles) is likely the main contributor to the development of posterior fossa syndrome. Medulloblastoma tumors are very close to these brain structures, and this is the most common tumor in patients with posterior fossa syndrome. Researchers hope that improvements in surgical techniques will reduce the occurrence of this condition.

Care for Children with Posterior Fossa Syndrome

Supportive care is the main treatment available for posterior fossa syndrome. Specific symptoms are addressed using a combination of therapies including: 

  • Speech Therapy
  • Physical Therapy
  • Occupational Therapy
  • Cognitive Assessment and Rehabilitation
  • Psychology and Behavior
  • School Support and Accommodations
  • Clinical Nutrition

Tips for Families Facing Posterior Fossa Syndrome

Get support. Posterior fossa syndrome can be especially challenging for patients and families. Parents feel helpless and frustrated when they can’t soothe or communicate with their child. As children begin to recover, they also report being frustrated that they were able to understand but could not communicate or express thoughts and feelings. It is hard for families to know what to expect or what to do to help their child. Other families who have been through a similar experience can be a source of support and advice. An experienced care team is also important to make sure patients and families have the resources they need for the recovery journey.

Manage expectations. Posterior fossa syndrome is very unpredictable. Recovery looks different for each patient, and each symptom can have a different time course. Although other families can be a source of help and encouragement, it is important to avoid setting expectations based on another patient’s journey.

Find information and ask questions. Posterior fossa syndrome is a rare condition. Many rehabilitation specialists have never worked with a child with the condition. Parents are important advocates for their child. They can work with the care team to make sure their child has appropriate specialists and support services, especially as the child transitions to outpatient or long-term care.

Questions to ask the care team about posterior fossa syndrome:

  • Does my child have any additional risk factors?
  • What should I watch for after surgery?
  • How will my child be monitored after surgery?
  • What treatments are available if my child shows symptoms of posterior fossa syndrome?
  • What can I do to help my child during recovery?

Use assistive devices and strategies as recommended by your care team. A variety of resources are available for patients and families to support communication, physical mobility, and activities of daily living.

A speech therapist may recommend the use of communication aids such as gestures, hand signals, sign language, and boards or devices to allow children to express wants and needs.

A physical therapist can help families make decisions about mobility equipment and help measure and fit patients with equipment such as a wheelchair, walker, cane, and/or leg braces. Patients often use many different types of equipment during their recovery. They may use some equipment for certain activities and not for others. For example, a child may use a walker to move around at home but will use a wheelchair for longer distances, such as going to the store or to school.

An occupational therapist may recommend specialized equipment to help with daily activities like bathing and using the restroom. Tools such as modified pencils and adapted feeding utensils may also be recommended to make tasks easier. In some cases, orthotics for the child’s hands may be prescribed to help the child with fine motor tasks.

Be patient with therapy. Patients and families may become frustrated when progress is hard to see. However, continuing therapy is important, even if progress seems slow. Ongoing monitoring and long-term support, including academic accommodations, can help promote quality of life after posterior fossa syndrome.

Reviewed: September 2018