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HomeHealth articlescerebellar hypoplasiaWhat Is Cerebellar Hypoplasia?

Cerebellar Hypoplasia - Symptoms, Diagnosis, and Treatment

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Cerebellar hypoplasia can affect either different parts of the entire cerebellar vermis or the entire cerebellar hemispheres or may involve the entire cerebellum.

Medically reviewed by

Dr. Prakashkumar P Bhatt

Published At January 9, 2023
Reviewed AtJuly 27, 2023


Cerebellar hypoplasia (CH) is characterized by decreased cerebellum volume with preserved shape. In contrast, cerebellar dysplasia is characterized by an abnormality in the maturation of tissue cells. As a result, the size of the cerebellum is either smaller than normal or is not formed completely.

It is generally associated with several congenital malformations syndromes like Walker-Warburg syndrome, inherited metabolic syndromes like Williams syndrome, and some neurodegenerative disorders such as ataxia telangiectasia. Mutations in the VLDLR (Very Low Density Lipoprotein Receptor) gene usually cause it. The gene makes a protein, such as a very low-density protein, which helps guide the movement of the developing nerve cells to their exact locations in the brain.

Therefore, the mutated gene prevents the developing nerve cells from reaching the parts of the brain where they are needed. Cerebellar anomalies can affect either different parts or all of the cerebellar vermis or one or both of the cerebellar hemispheres, or they may involve the entire cerebellum. Therefore, it is important to differentiate between these various forms because each specifically characterizes a different disorder. Neuroimaging using magnetic resonance imaging (MRI) has been a key diagnostic tool to categorize CH based on the pattern of cerebellar involvement and the presence of associated brainstem and cerebral anomalies.

The cerebellum comprises three lobes that are anterior, posterior, and flocculonodular, and ten lobules and is divided into a midline vermis and two hemispheres. The inferior and middle cerebellar peduncles carry the main inputs to the cerebellum:

  • The pontocerebellar and spinocerebellar fibers that form the mossy fibers synapse onto the granule cells.

  • The olivocerebellar fibers form the climbing fibers and synapse with the Purkinje cells. All the outputs from the cerebellum are relayed by the three cerebellar nuclei (dentate, interposed, and fastigial) and are carried by the superior fibers.

Cerebellar hypoplasia may be classified based on the extent of cerebellar involvement:

  • Unilateral Cerebellar Hypoplasia: It affects only one cerebellar hemisphere with or without the involvement of the vermis, and it usually arises from an antenatal vascular hemorrhagic or ischemic insult. The clinical presentation differs from an asymptomatic incidentally detected pathology to one with severe neurologic deficits. The most common clinical features include developmental and speech acquisition delay, hypotonia, ataxia, and eye movement disorders. However, atypical features such as seizures have also been seen in a few cases. In addition, the involvement of the vermis is often associated with cognitive decline and truncal ataxia.

  • Cerebellar hypoplasia with predominant involvement of vermis.

  • Global cerebellar hypoplasia includes both the vermis and cerebellar hemispheres.

  • Hypoplasia involving the pons and cerebellum is usually associated with an intense intellectual deficit and delayed or absent psychomotor milestones. In most cases, the disease is usually very fatal early in life. There are two basic types of pontocerebellar hypoplasia:

    • Type 1: There is congenital central and peripheral motor dysfunction leading to early death, mostly before one year. The abnormally small cerebellum and brainstem, including the pons, are accompanied by degeneration of the anterior horn cells. Due to the involvement of the anterior horn cell, type 1 mimics infantile spinal muscular atrophy. The hypoplasia of the pons and cerebellum and spinal anterior horn cell degeneration is associated with pronounced reactive changes or gliosis. It is also associated with reduced fetal movement. The pregnancy may sometimes be complicated by polyhydramnios.

    • Type 2: There is progressive congenital microcephaly along with extrapyramidal dyskinesia. Severe chorea and epilepsy are frequent, while the involvement of the anterior horn is absent in this type. The main feature distinguishing type 1 from type 2 is that anterior horn cells are not involved in type 2. Characteristically, unlike type 1, pregnancy is normal. However, the newborn may show breathing difficulties or respiratory failure at birth, requiring mechanical ventilatory support.

What Are the Signs and Symptoms of Cerebellar Hypoplasia?

Symptoms of cerebellar hypoplasia include

  • Floppy muscle tone.

  • Developmental or speech delay.

  • Problem with walking and balance.

  • Intellectual disability.

  • Seizures.

  • Involuntary side-to-side movement of the eyes.

  • Headache.

  • Clumsiness.

  • Hearing loss.

  • Dizzy spells.

What Are the Lab investigations to Be Carried Out?

The investigations to be carried out are:

  • Physical Examination: It may show remarkable results if any of the following is observed

    • Truncal ataxia.

    • Abnormal ocular movements.the

    • Hypotonia.

    • Intentional tremors.

An accurate clinical assessment will help arrange the appropriate investigation procedures. Extensive neuroradiological imaging with the magnetic resonance of the brain is the most useful method to identify which investigations are required further. It confirms a cerebellar lesion's clinical suspicion and provides information about its distribution, extent, and morphology.

  • Magnetic Resonance Imaging (MRI): Neuroimaging helps differentiate cerebellar hypoplasia from atrophic changes. Hypoplasia, dysplasia, or atrophy can be easily identified if the same subject is examined repeatedly at several intervals. Hypoplasia and dysplasia remain unchanged, whereas the involutional process of atrophy progresses and worsens over time.

What Are the Differential Diagnosis for Cerebellar Hypoplasia?

Differential diagnoses include

  • Diffuse cerebellar atrophy.

  • Pontocerebellar hypoplasia.

  • Unilateral cerebellar hypoplasia.

  • Isolated inferior vermian hypoplasia.

  • Joubert syndrome or vermian aplasia.

  • Dandy-Walker malformation.

What Is the Treatment of Cerebellar Hypoplasia?

The prognosis of the disease and the treatment protocol typically depends upon the underlying cause. For example, cerebellar hypoplasia associated with non-progressive disorders such as abnormal brain formation during fetal development has a relatively better prognosis. In contrast, cerebellar hypoplasia associated with progressive conditions has a poor prognosis.


Cerebellar hypoplasia is characterized by decreased cerebellum volume with preserved shape. The size of the cerebellum is either smaller than normal or is not formed completely. It is generally seen in association with several congenital malformations. The symptoms include floppy muscle tone, developmental or speech delay, problems with walking and balance, intellectual disability, hearing loss, and headache. Neuroradiological imaging with the magnetic resonance of the brain is the most practical method to identify such abnormalities. Cerebellar malformations are now diagnosed with increasing frequency in the fetal and neonatal periods. Therefore, accurate prognostic information to guide parental decision-making has become essential.

Frequently Asked Questions


What Are the Causes of Cerebellar Hypoplasia?

The leading causes of cerebellar hypoplasia are genetic abnormalities, pregnancy-related disorders, exposure to chemicals or medications, and malnourishment. A smaller or less developed cerebellum may result from several causes interfering with the normal development of the cerebellum. It is frequently a congenital disease that impairs motor skills and coordination.


What Is the Life Expectancy of People With Cerebellar Hypoplasia?

The condition is usually fatal in most cases at an early age. The life duration has varied, from neonatal death to approximately 20–25 years. Few people have lived into their second or third decades—usually patients with PCH type 2. However, depending on the severity of the disease and related health problems, people with cerebellar hypoplasia have vastly differing life expectancies. With supportive treatment, some may lead reasonably everyday lives, but others with more severe cases may experience difficulties that shorten their lives.


Can Cerebellar Hypoplasia Resolve on Its Own?

Due to the structural underdevelopment of the cerebellum, cerebellar hypoplasia usually does not resolve on its own. But with the right supporting care and rehabilitation, people can adjust and even somewhat enhance their motor skills. There is variation in the extent of improvement, and care frequently concentrates on treating related symptoms instead of the core illness.


Can Cerebellar Hypoplasia Affect Intelligence?

With little direct impact on IQ, cerebellar hypoplasia mostly affects motor abilities and coordination. Tasks requiring both physical and cognitive coordination may be difficult for some people, though, as the cerebellum involves some cognitive processes. The capacity to carry out intricate tasks requiring coordination may be hampered to varied degrees, but intelligence per se is usually unaffected.


Is Cerebellar Hypoplasia a Life-long Condition?

Cerebellar hypoplasia is, in most cases, a permanent disorder. It involves the cerebellum's structural underdevelopment, which lasts a lifetime. The underlying anatomical problem persists even though people may adapt and enhance their motor skills with assistance and rehabilitation. Rather than treating the illness, management focuses on symptom relief and maximizing functioning.


What Does a Small Cerebellum in a Baby Mean?

Underdevelopment of the cerebellum, a part of the brain essential for motor coordination, is indicated by a small cerebellum in a baby, a condition known as cerebellar hypoplasia. This may result in challenges with posture, voluntary muscular movements, and balance. Genetics, prenatal infections, or other developmental problems could cause the illness. Early identification and treatment are essential to control related symptoms.


Is Cerebellar Hypoplasia a Genetic Disorder?

Although it is not necessarily a genetic condition, cerebellar hypoplasia can have hereditary causes. The disorder may be caused by genetic abnormalities that impact cerebellar development. External variables, such as diseases contracted during pregnancy, may also be involved. Cerebellar hypoplasia has a complex etiology that is not always solely genetic due to the interaction of hereditary and environmental variables.


Does Aging Exacerbate Cerebellar Hypoplasia?

As a structural ailment present from birth, cerebellar hypoplasia does not deteriorate with age. As people age, a natural reduction in overall motor function and coordination may make the condition more apparent. Throughout life, managing symptoms with supportive interventions and flexible approaches is critical.


What Would Happen if There Was No Cerebellum?

One of the most important brain structures for motor control and coordination, the cerebellum, would be substantially compromised regarding voluntary motions, balance, and posture. People would struggle greatly with chores that needed to be accurate and well-coordinated. There may be some impact on cognitive processes. A person with such a condition may not survive without the cerebellum's critical services, which is incompatible with everyday existence.


Could the Virus Be a Cause of Cerebellar Hypoplasia?

When infected during pregnancy, some viruses, such as the feline panleukopenia virus in cats, can result in cerebellar hypoplasia. In humans, exposure to chemicals like alcohol or congenital diseases like cytomegalovirus (CMV) may play a role. Cerebellar hypoplasia risk, however, mainly depends on the particular virus and the timing of infection during pregnancy.


Can Cerebellar Hypoplasia Be Fatal?

In most cases, cerebellar hypoplasia is not lethal on its own. On the other hand, the way it affects balance and motor coordination may make accidents and injuries more likely. The degree of related symptoms varies, and those with more severe cerebellar hypoplasia could have difficulties going about their everyday lives. Enough supervision, assistance, and preventative actions are necessary to raise the standard of living.


What Other Name Does Cerebellar Hypoplasia Go By?

A different name for cerebellar hypoplasia is "cerebellar underdevelopment." The cerebellum is underdeveloped in this neurological disorder, which impairs balance and motor coordination. Pregnancy-related environmental factors, infections, or genetic factors can all contribute to the illness, which is frequently congenital. The phrase "cerebellar hypoplasia" is commonly used in veterinary and human medicine.


Can Cerebellar Hypoplasia Develop at a Later Age?

Most cases of cerebellar hypoplasia are congenital, meaning that developmental problems cause the disorder to exist from birth. It usually doesn't develop later in life. Nonetheless, some acquired disorders can resemble signs of cerebellar dysfunction, such as tumors or trauma affecting the cerebellum. Adults who experience any new symptoms should see a healthcare provider for a complete evaluation.


Could Cerebellar Hypoplasia Be Not So Severe?

Yes, there can be an extensive range in cerebellar hypoplasia severity. Sometimes, people have minor symptoms that allow them to function reasonably normally, as long as they have the right assistance and accommodations. Some people could struggle with motor coordination more severely than others. The degree of disability can vary from minor to severe, depending on the degree of cerebellar underdevelopment. This can have an overall influence on daily life.


Does Cerebral Hypoplasia Cause Pain?

Pain is not a direct result of cerebellar hypoplasia. However, because of their issues with balance, coordination, or movement, people with this illness may feel pain or discomfort, which increases their risk of accidents or injury. Although it's not a direct sign of cerebellar hypoplasia, pain management may be required to address these problems.
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Dr. Prakashkumar P Bhatt
Dr. Prakashkumar P Bhatt



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