Left Brain vs Right Brain: Why Brain Tumor Location Matters

Left Brain vs Right Brain: Why Brain Tumor Location Matters

Reviewed by Preston Robert Tisch Brain Tumor Center Specialists | Last updated: October 2026

When a brain tumor develops, its location can influence which symptoms appear, which abilities may be affected, and what treatment options are appropriate. A tumor in the left cerebral hemisphere may affect language or movement on the right side of the body, while a tumor in the right hemisphere may affect spatial awareness or movement on the left. However, these patterns are not universal: symptoms depend on the specific brain region involved, the person's brain organization, the tumor's size and type, and whether nearby structures are affected.

The difference between a left-sided and right-sided brain tumor is not simply logic versus creativity. Each hemisphere contains several regions responsible for different functions, and many abilities depend on networks that connect both sides of the brain. Understanding the tumor's exact location helps clinicians interpret symptoms, plan treatment, and anticipate possible effects on daily life.

Key Takeaways: Left Brain vs. Right Brain and Tumor Location

• Tumor location matters: A tumor's position can affect speech, movement, memory, vision, behavior, and other neurological functions.
• The left and right hemispheres have different specializations: Language is often more strongly represented on the left, while some spatial and attention functions rely more heavily on the right.
• Symptoms do not follow a universal pattern: The precise location, size, growth, and effects on surrounding tissue all influence what a person experiences.
• Movement and sensation may be affected on the opposite side: Brain pathways often cross, so a tumor affecting motor or sensory regions on one side may cause symptoms on the other side of the body.
• Location can influence treatment planning: Neurosurgeons and other specialists consider the tumor's relationship to important functional areas when evaluating treatment options.
• A symptom does not identify a tumor's location by itself: Neurological examination and imaging are needed to determine what may be causing a change.

The National Cancer Institute's guide to brain and spine tumor anatomy explains how tumor location relates to brain function and possible symptoms.

What Is the Difference Between the Left and Right Sides of the Brain?

The cerebrum, the largest part of the brain, is divided into two hemispheres: left and right. Each hemisphere contains frontal, parietal, temporal, and occipital lobes, which contribute to different functions. Although the hemispheres have some specialized roles, most complex activities depend on communication between multiple brain regions.

This distinction matters when a tumor develops because its effects depend on more than which side of the brain it occupies.

What Does the Left Side of the Brain Control?

For many people, the left hemisphere plays a major role in language, including speech production, reading, and understanding words. It also contributes to movement, sensation, memory, attention, and other cognitive functions.

A tumor affecting certain left-sided regions may cause:

• Difficulty finding words or forming sentences.
• Trouble understanding spoken or written language.
• Changes in reading, writing, or naming familiar objects.
• Weakness or altered sensation on the right side of the body.
• Changes in planning, attention, or other cognitive abilities.

These effects depend on the specific area involved. A tumor near language-related regions, for example, may affect communication, while one involving motor pathways may cause weakness. A left-sided tumor does not necessarily cause all, or any, of these symptoms.

What Does the Right Side of the Brain Control?

The right hemisphere contributes to spatial processing, attention, visual interpretation, and awareness of the environment. It also participates in language-related communication, memory, emotion, and movement.

A tumor affecting particular right-sided regions may cause:

• Difficulty judging distances or navigating familiar spaces.
• Changes in attention to one side of the environment.
• Difficulty interpreting visual or spatial information.
• Weakness or altered sensation on the left side of the body.
• Changes in coordination or other cognitive abilities.

For example, someone might begin misjudging the distance between objects or have trouble noticing things on one side of a space. These changes are not specific to brain tumors, however, and require medical assessment to determine their cause.

Is the Left Brain Logical and the Right Brain Creative?

Not in the simple way popular descriptions often suggest. The brain does have lateralized functions, meaning certain processes are more strongly associated with one hemisphere, but logical reasoning, creativity, emotion, and problem-solving involve distributed networks.

For brain tumor care, the clinically useful question is not whether a tumor affects the “logical” or “creative” side. It is which functional regions and connections are involved and how that location may affect the patient's abilities.

How Does Brain Tumor Location Affect Symptoms?

Brain tumors can develop in different parts of the cerebrum, cerebellum, or brainstem. Symptoms reflect the functions of the affected area, but they can also result from swelling, pressure on nearby structures, or disruption of communication between regions.

The following overview explains common patterns by brain region. These are possibilities, not a diagnostic checklist: the same tumor location can produce different symptoms in different people.

Why Can a Tumor Cause Symptoms on the Opposite Side of the Body?

Many motor and sensory pathways cross as they travel between the brain and body. As a result, a tumor affecting certain motor regions or pathways in the left hemisphere may cause weakness on the right side, while a right-sided lesion may affect the left side.

However, the relationship is not absolute. Symptoms depend on the precise location of the tumor and which pathways are affected. Some tumors cause changes in speech, vision, coordination, or cognition without producing obvious weakness.

New weakness, facial drooping, difficulty speaking, or sudden loss of coordination warrants emergency medical assessment. These symptoms can have several causes and should not be attributed to a brain tumor without evaluation.

How Does Tumor Location Affect Speech, Memory, and Behavior?

A brain tumor may affect abilities that are less visible than movement or vision. Changes in communication, concentration, judgment, or behavior can be particularly difficult for families to interpret because they may develop gradually.

Language and Communication

Language depends on interconnected brain networks, which are most often left-dominant but vary among individuals. A tumor affecting language-related areas or their connections may make it difficult to find words, name objects, understand speech, read, or write.

Some people know what they want to say but struggle to produce the words. Others may speak fluently but have difficulty understanding what someone else is saying. These patterns can help clinicians determine which functions need closer evaluation.

When a tumor is near important language areas, the treatment team may consider additional functional assessment or specialized surgical planning to help preserve communication abilities.

Memory and Concentration

Memory is not controlled by one isolated area. The temporal lobes and other interconnected structures play important roles in forming and retrieving memories, while attention and executive networks help people organize information and complete tasks.

Depending on its location and other effects, a tumor may contribute to forgetfulness, difficulty concentrating, slower information processing, or trouble learning new information. These symptoms may also be influenced by seizures, medications, sleep disruption, stress, or treatment.

Tracking when changes began and how they affect daily activities can help the care team assess the problem more accurately.

Behavior and Personality

Tumors affecting frontal networks may contribute to changes in judgment, motivation, impulse control, or emotional regulation. Family members may notice that a person seems less organized, behaves differently in social situations, or has difficulty completing tasks that were previously routine.

Such changes do not automatically indicate a brain tumor, and they are not exclusive to frontal-lobe lesions. The significance depends on the pattern of symptoms, how they developed, and the results of medical evaluation.

Duke's related article, How Brain Cancer Affects Daily Life, explores the broader effects brain tumors can have on physical abilities, cognition, emotions, and daily routines.

Does the Side of a Brain Tumor Affect Treatment?

Yes. Tumor location can influence which treatments are feasible and what risks need to be considered, particularly when the tumor is near areas responsible for speech, movement, vision, or other important functions.

However, the left-versus-right distinction alone does not determine treatment. Clinicians also consider the tumor's type, grade, molecular characteristics, size, growth pattern, symptoms, and the patient's overall health.

Why Surgeons Consider Functional Brain Areas

When surgery is being considered, the team evaluates how close the tumor is to critical structures and whether removing it could affect important functions. The objective is to remove as much tumor as can be done safely while preserving neurological function.

In selected cases, preoperative functional imaging, specialized mapping, or other assessments may help identify important language or motor regions. The appropriate approach depends on the tumor's location, the planned procedure, and the patient's needs.

A tumor near an important functional area may require a different surgical strategy from one in a region that can be approached with fewer functional risks. This is one reason treatment planning must be individualized.

Does Tumor Location Determine Prognosis?

Location can influence prognosis indirectly by affecting symptoms, surgical options, and the risks associated with treatment. A tumor close to a critical structure may be more difficult to remove safely, for example, while a tumor in another region may be more accessible.

Still, location is only one part of the picture. Tumor type, grade, molecular findings, response to treatment, and whether the disease has spread can all influence outcomes.

Two patients with tumors in similar brain regions may therefore receive different recommendations and have different prognoses. A specialist can explain how location interacts with the other details of an individual diagnosis.

How Do Doctors Determine Where a Brain Tumor Is Located?

Doctors use imaging and clinical assessments to understand the tumor's position and its possible effects. The diagnostic process may include:

1. MRI of the brain: Provides detailed images that help show the tumor's location, size, appearance, and relationship to nearby structures.
2. Neurological examination: Assesses functions such as strength, coordination, sensation, vision, speech, and cognition.
3. Additional functional assessment: When appropriate, specialized tests may help identify important brain areas before treatment.
4. Tissue and molecular testing: When biopsy or surgery is performed, analysis of the tumor can establish its type and provide information that affects treatment planning.

An MRI can show where a tumor is located, but imaging does not always establish its exact type or behavior. The care team interprets the findings alongside symptoms, examination results, and, when needed, pathology.

Patients who want to better understand their imaging can read Duke's guide to understanding brain MRI results.

What Should You Do If You Notice New Neurological Symptoms?

Symptoms such as persistent changes in speech, movement, vision, balance, memory, or behavior can have many causes. Their presence does not mean someone has a brain tumor, but new, unexplained, persistent, or worsening neurological changes should be evaluated by a healthcare professional.

Seek emergency care for sudden neurological symptoms, including new one-sided weakness, difficulty speaking, sudden loss of vision, a first seizure, or a sudden severe headache.

For a medical appointment, it can help to record when symptoms began, how frequently they occur, whether they are progressing, and how they affect everyday activities. This information can help clinicians determine what evaluation is appropriate.

Duke's article on warning signs of brain tumors in children offers additional information for families concerned about new neurological changes in a child.

Understanding Brain Tumor Location at Duke's Preston Robert Tisch Brain Tumor Center

Brain tumor evaluation and treatment can involve neurosurgery, neuro-oncology, neuroradiology, pathology, rehabilitation, and other specialties. Understanding where a tumor is located, and which functions may be affected, helps the care team consider treatment options and potential effects on daily life.

The Preston Robert Tisch Brain Tumor Center at Duke provides information about brain tumor care and related clinical programs. Patients and families can use the center's resources to learn more about diagnosis, treatment considerations, and questions to discuss with their medical team.

The most important distinction is not that one side of the brain is responsible for logic and the other for creativity. It is that each tumor affects a particular set of structures and connections. Knowing the exact location helps clinicians understand symptoms, plan treatment, and discuss which abilities may need monitoring or rehabilitation.

FAQs: Left Brain vs Right Brain: Why Brain Tumor Location Matters

What are the symptoms of a tumor on the left side of the brain?

Symptoms depend on the exact region involved, but a left-sided tumor may affect language, speech, reading, writing, or movement and sensation on the right side of the body. Some tumors also affect memory, attention, or other cognitive functions. These patterns are not universal because brain functions rely on interconnected networks and vary among individuals. Medical evaluation and imaging are needed to determine what is causing a person's symptoms.

What are the symptoms of a tumor on the right side of the brain?

A right-sided tumor may affect spatial awareness, visual processing, attention, or movement and sensation on the left side of the body, depending on its location. It can also affect other cognitive functions or cause symptoms such as seizures. Not every right-sided tumor produces these changes, and symptoms alone cannot reliably identify where a tumor is located. A clinician evaluates the symptoms alongside neurological examination findings and imaging.

Is a left-sided brain tumor more dangerous than a right-sided brain tumor?

Neither side is inherently more dangerous in every case. The risks depend on the tumor's type, grade, size, growth, relationship to critical structures, and response to treatment. A tumor near a language or motor region may present specific treatment challenges, but that does not automatically make it more aggressive. The care team can explain how the location affects the risks and options for an individual patient.

Can a brain tumor change someone's personality?

A brain tumor can contribute to changes in behavior, judgment, motivation, or emotional regulation, particularly when it affects frontal networks or their connections. However, personality changes can have many other causes, and they do not establish that a tumor is present. New or progressive behavioral changes should be discussed with a healthcare professional, especially when accompanied by other neurological symptoms. Evaluation helps determine whether additional testing is needed.

Does the location of a brain tumor affect surgery?

Yes. The tumor's location can influence whether surgery is feasible, how much tumor can be removed safely, and which functions need particular protection. Surgeons may use imaging and, in selected cases, functional mapping to help plan an approach near important language or motor areas. Location is only one consideration, however; tumor type, size, and the patient's overall condition also affect treatment planning.

Can an MRI show which side of the brain has a tumor?

Yes. MRI can usually show the tumor's location and whether it involves the left hemisphere, right hemisphere, or another part of the brain. It can also help clinicians assess the tumor's size and relationship to nearby structures. However, MRI findings alone do not always establish the exact tumor type or determine how it will affect an individual. Doctors interpret the scan alongside clinical findings and any other necessary diagnostic tests.

This article is for educational purposes and does not replace medical advice, diagnosis, or treatment from a qualified healthcare professional.