Why is the back of my skull soft? Causes and risks explained

September 29, 2025 •

4 min read

While babies are famously known to have soft spots called fontanelles, an adult’s skull is made of fully fused, solid bone.

Therefore, the sensation of a soft spot on the back of the skull can be very alarming and is a finding that warrants immediate medical attention to determine the underlying cause and answer the question, Why is the back of my skull soft?

Quick Summary

The presence of a soft spot on an adult's skull is abnormal and can indicate a variety of serious underlying medical conditions, such as bone disorders, brain tissue softening, or complications from a past injury. It requires a comprehensive professional medical evaluation for an accurate diagnosis and treatment plan.

Key Points

Infant vs. Adult Skull: Unlike a baby's fontanelles, a soft spot on an adult's skull is abnormal and requires urgent medical investigation.
Potential Causes: Reasons for adult skull softness include genetic disorders, severe head trauma, increased fluid pressure inside the skull, or nutritional deficiencies.
Encephalomalacia (Brain Softening): A more severe cause can be softening of the brain tissue itself, which is often a result of stroke or traumatic injury and can be incurable.
Associated Symptoms: A soft skull, especially with headaches, dizziness, or confusion, signals a need for immediate medical evaluation to rule out a serious neurological issue.
Professional Diagnosis: Proper diagnosis requires a doctor's examination, often including imaging tests like a CT scan or MRI, to identify the root cause.
Do Not Ignore: The presence of an adult soft spot is not a minor issue and should never be self-diagnosed or left untreated.

Understanding the Skull: Infant vs. Adult

The human skull is not a single, solid bone at birth. In infants, the skull is composed of several bone plates separated by fibrous, membranous gaps called fontanelles. The posterior fontanelle, located on the back of the head, typically closes within the first few months of life, while the larger anterior fontanelle on top closes by around 18 months to 2 years of age. These flexible, soft spots serve two crucial purposes: to allow the baby's head to pass through the birth canal and to accommodate the rapid growth of the infant's brain.

In a healthy adult, the skull bones have completely fused and ossified, forming a single, rigid protective casing for the brain. The presence of a truly soft area on an adult's skull is highly unusual and never normal. It signifies an underlying issue that needs to be investigated by a healthcare professional immediately.

Potential Medical Causes for an Adult's Skull Softness

Softening of Brain Tissue (Encephalomalacia)

In some cases, the sensation of a soft skull may not be a problem with the bone itself, but rather with the underlying brain tissue. Encephalomalacia refers to the localized softening of brain tissue, often as a result of a stroke, inflammation, or a severe traumatic brain injury. This condition is incurable, as brain tissue does not regenerate, and it can have lifelong consequences. While the bone is intact, the underlying tissue damage can create a sense of softness or vulnerability.

Congenital and Genetic Conditions

Certain genetic disorders and congenital birth defects can cause the skull bones to form improperly or fail to fuse completely, leaving open fontanelles or soft areas into adulthood. Conditions include:

Cleidocranial Dysplasia: A rare genetic condition that affects the development of bones and teeth. It can lead to an open anterior fontanelle that persists throughout life.
Osteogenesis Imperfecta: Also known as "brittle bone disease," this condition causes bones to be fragile and break easily. In severe cases, it can affect skull formation and density.
Congenital Hypothyroidism: An underactive thyroid gland at birth can delay bone maturation, leading to delayed closure of fontanelles.

Increased Intracranial Pressure

Increased pressure inside the skull can sometimes cause bones to separate or become soft. A common cause is hydrocephalus, a condition where there is an excess accumulation of cerebrospinal fluid (CSF) in the brain. This buildup of fluid can exert pressure on the skull bones, potentially leading to softening, especially in cases where a fontanelle failed to close properly.

Nutritional Deficiencies

Inadequate levels of certain nutrients, most notably Vitamin D and calcium, can lead to conditions like rickets. While most commonly associated with childhood, severe or prolonged deficiencies can affect bone density and integrity in adults, potentially contributing to areas of weakness in the skull.

Trauma and Other Physical Factors

Head Injury

A traumatic head injury, such as from an accident or fall, can damage the skull bone. While this most often results in a solid scar or a hematoma (blood clot) that may feel like a lump, it can, in rare cases, disrupt the bone structure and leave a persistent soft spot. Any head injury, especially if severe, must be medically evaluated to rule out serious internal damage, such as bleeding within the skull.

Previous Surgery

Individuals who have undergone a craniotomy or other skull surgery may have areas of the bone that feel different. While the bone is typically repaired, the repaired section or surrounding tissue might have a different texture or feel slightly softer than the original bone. However, a doctor should always assess any new or worsening symptoms.

Non-Osseous Lumps and Bumps

Sometimes, a person may perceive a lump or soft area on their skull that is not related to the bone itself. Examples include harmless fatty growths (lipomas) or cysts that develop under the scalp. However, a lump should not be mistaken for the actual softening of the skull itself, and a doctor’s examination is necessary for a definitive diagnosis.

Infant Fontanelle vs. Adult Soft Spot: A Comparison


Feature	Infant Fontanelle	Adult Soft Spot
Normalcy	Expected and necessary for development.	Highly unusual and indicates a serious underlying problem.
Purpose	Facilitates birth and accommodates rapid brain growth.	Serves no functional purpose and is a sign of disease or injury.
Closure Timeline	Posterior closes by ~3 months, Anterior by ~18-24 months.	Should be fully closed; persistence is a red flag.
Underlying Cause	Normal biological function.	Genetic disorder, trauma, encephalomalacia, hydrocephalus, or nutritional deficiency.
Required Action	Monitored by a pediatrician for normal development.	Requires immediate medical evaluation by a doctor or neurologist.

When to Seek Medical Attention

If you discover a soft spot on your adult skull, it is crucial to consult a healthcare professional immediately for a proper diagnosis. Do not ignore this symptom. Prompt medical attention is especially vital if you experience additional symptoms alongside the soft spot, including:

Persistent or severe headaches
Dizziness, vertigo, or issues with balance
Numbness or weakness in your limbs
Confusion, memory problems, or personality changes
Visual disturbances or double vision
Fever
Loss of consciousness or seizures

For more information on when to seek urgent care for head-related symptoms, consult the Cleveland Clinic or another authoritative health source. While the link discusses occipital neuralgia, it offers valuable guidance on when head-related symptoms require immediate medical attention.

Conclusion

In summary, while a soft spot is a normal and necessary feature of an infant's skull, it is a significant and serious symptom in an adult. The reasons why the back of my skull is soft range from congenital issues and metabolic disorders to traumatic injuries or severe intracranial pressure. Because the underlying causes can have serious neurological implications, professional medical evaluation is essential. Do not attempt to self-diagnose or wait for symptoms to worsen; consulting a doctor is the most important and responsible step to take for your health.

Frequently Asked Questions

While sometimes what feels like a soft spot might be a benign cyst or fatty deposit, any sensation of softness directly on the skull bone is not normal for an adult and should be evaluated by a doctor to rule out more serious medical conditions.

The posterior fontanelle, at the back of the head, typically closes by around 2-3 months of age. The larger anterior fontanelle on top usually closes between 18 and 24 months.

Encephalomalacia is the softening of brain tissue, often following an injury or stroke. While the skull bone may be intact, the underlying tissue damage could create the sensation of softness. It is a very serious condition requiring medical care.

Yes, in rare cases, a past severe head injury or surgery could lead to a permanent irregularity in the skull bone that feels like a soft spot. It is vital to get any new or changing symptoms checked by a doctor.

You should start by seeing your primary care physician, who will likely refer you to a specialist such as a neurologist or a neurosurgeon for a more detailed evaluation and diagnosis.

Yes. If a soft spot is accompanied by severe headaches, fever, vision changes, confusion, or any loss of consciousness, you should seek immediate emergency medical care.

Severe, prolonged nutritional deficiencies, particularly in Vitamin D and calcium, can lead to weakened bones and conditions like rickets, which could potentially cause areas of the skull to be less dense.