Can Sjögren-Larsson Syndrome Be Misdiagnosed As CP?

It is understandable to wonder if your child’s cerebral palsy (CP) diagnosis might actually be Sjögren-Larsson syndrome (SLS). Because both conditions can cause early developmental delays and stiff, tight muscles (spasticity) in the legs, SLS is frequently misdiagnosed as CP in early childhood ^[1][2]. However, while cerebral palsy is typically caused by a static brain injury before or during birth, SLS is a rare, inherited metabolic disorder ^[3]. The key to telling them apart lies in looking for symptoms outside the muscles, such as severe dry skin (ichthyosis) present since birth, specific eye changes, and distinct brain imaging results ^[4].

Why SLS Looks Like Cerebral Palsy

In early childhood, the neurological symptoms of SLS look very similar to spastic diplegic cerebral palsy (a type of CP that primarily affects the legs) ^[1][2]. In both conditions, you might notice:

• Motor delays: Taking longer to sit, crawl, or walk ^[4].
• Spasticity: Stiff, tight muscles, often more severe in the legs than the arms ^[4].
• Premature birth: SLS is associated with a high rate of preterm birth (around 36 weeks), which is also a common risk factor for CP ^[4].
• Intellectual disability: Both conditions can involve cognitive delays, though they are a core feature of SLS ^[4].

Key Differences to Look For

While the movement issues overlap, SLS has distinct features that are not found in standard cerebral palsy ^[4].

1. Skin Changes (Ichthyosis)

The most noticeable difference is the skin. Children with SLS are born with ichthyosis, a condition that causes thick, dry, and scaly skin ^[5][6].

• At birth, the skin may appear red and thickened.
• Over time, it evolves into a dry, scaly appearance.
• A very distinguishing feature of SLS-related ichthyosis is intense itching (pruritus), which is rare in other skin scaling disorders ^[4]. Unlike typical dry skin or eczema, this severe itching usually does not respond to standard over-the-counter baby lotions or eczema creams ^[4].

2. Eye Findings (Macular Dystrophy)

SLS causes unique changes in the eyes that a specialized eye doctor (ophthalmologist) can see during an exam. These appear as glistening white dots (crystalline inclusions) in the macula, which is the center of the retina responsible for sharp, detailed vision ^[4]. Because these dots are small, they are generally not seen during a standard pediatric vision check; you will need to request a specialized, dilated eye exam to look for them ^[7]. They are a strong indicator of SLS, though they might not develop until after infancy ^[4].

3. Progressive Symptoms

Cerebral palsy is considered a “static” condition—meaning the original brain injury does not get worse over time. In contrast, SLS can sometimes show slow neurological progression ^[8][9]. While cognitive deficits usually remain stable, some patients may later develop new movement issues like tremors or involuntary muscle contractions (dystonia) ^[8][4]. In daily life, this means a child who was previously stable might start experiencing new types of involuntary movements or clumsiness as they grow older.

4. Brain Imaging (MRI and MRS)

If your child had a brain MRI, doctors might have seen changes in the brain’s white matter (leukoencephalopathy), which can happen in both conditions. However, a specialized type of scan called Magnetic Resonance Spectroscopy (MRS) can reveal a distinctive signature for SLS. MRS is not a separate machine, but rather a specialized setting that can be run while the child is already in the MRI scanner. Because it is not always done automatically during a standard MRI, your neurologist must specifically request it ^[4].

Because SLS is caused by an enzyme deficiency (specifically, an enzyme called Fatty Aldehyde Dehydrogenase or FALDH), fatty alcohols build up in the body and brain ^[10][3]. An MRS scan will show this build-up as an abnormal “lipid peak at 1.3 ppm,” which strongly points to SLS ^[4][11].

When to Ask for Testing

You should talk to your doctor about testing if your child has a cerebral palsy diagnosis but also has:

• Dry, scaly, or intensely itchy skin that has been present since birth or early infancy ^[2].
• Glistening white dots identified during a dilated eye exam ^[7].
• An MRI that shows unexplained white matter changes, or an MRS scan showing the characteristic lipid peak ^[4].
• New neurological symptoms developing over time, such as tremors, which are not typical for static CP ^[8].

Doctors can order a blood test to check your child’s FALDH enzyme levels, or they can order genetic testing (a blood test or cheek swab) to look for changes in the ALDH3A2 gene, which causes SLS ^[12][13].

Confirming an SLS diagnosis is critically important because it directly changes how you manage your child’s health ^[4]. It opens the door to targeted prescription therapies for their intense skin itching and specialized eye care that are not part of a standard CP treatment plan ^[4]. Furthermore, because SLS is an inherited trait (autosomal recessive), having a clear diagnosis provides important information for future family planning ^[10][3].