Symptoms and the Path of Progression

Understanding the path of NESCAV syndrome requires a shift in how we think about neurological conditions. Unlike a “static” condition like cerebral palsy, where the initial brain injury does not get worse over time, NESCAV is neurodegenerative ^[1]. This means that while your child will continue to learn and grow, the underlying condition can cause new symptoms to appear or existing ones to change as they get older ^[2].

It is important to note that the statistics presented below come from cohort studies of the broader KAND spectrum. They highlight common trends but cannot predict your individual child’s course. Some children will have many of these symptoms, while others may have only a few.

Early Signs in Infancy

For many families, the first signs appear in the first year of life ^[3]. These early indicators often include:

• Infantile Hypotonia: This is low muscle tone, often called “floppiness.” It affects many children in the KAND spectrum ^[2]. You might notice your baby has trouble holding their head up or feels “heavy” in your arms.
• Global Developmental Delay: Most children will reach milestones like sitting, crawling, and babbling later than their peers ^[2].
• Vision Challenges: Early problems often involve Optic Nerve Atrophy (a weakening of the cable connecting the eye to the brain) or Cortical Visual Impairment (where the eyes work, but the brain struggles to process the image) ^[4][3].

The Motor Evolution: From “Floppy” to “Stiff”

One of the most distinct features of NESCAV is how muscle tone changes over time. Many children begin with low tone (hypotonia) but gradually develop high tone, or spasticity ^[2].

• Spastic Paraparesis: This is a progressive stiffness and weakness, typically in the legs. Spasticity often becomes more pronounced as children get older ^[2].
• Changes in Walking: While some children learn to walk independently, the progressive nature of spasticity and ataxia (problems with balance and coordination) means that some may eventually need more support, such as walkers or wheelchairs, to stay mobile ^[2].

Changes in the Brain and Nervous System

Doctors use MRIs to track how the condition affects the brain. A common finding is Cerebellar Atrophy, which is a shrinking of the part of the brain that helps control balance ^[5].

• Progression on Imaging: On serial MRIs taken years apart, doctors may see that this atrophy progresses or that the cerebral hemispheres (the larger parts of the brain) also show signs of volume loss ^[1][6].
• Peripheral Neuropathy: Some children develop damage to the nerves outside the brain and spinal cord, which can cause numbness, tingling, or further weakness in the hands and feet ^[7].

Communication and Speech

Communication is a major area of focus. A vast majority of children assessed in KAND cohorts experience some form of language impairment ^[8].

• Dysarthria: This is a motor speech disorder where the muscles used for speech are weak or difficult to control, making words sound slurred ^[8].
• AAC Use: Because speaking can be physically exhausting or difficult, many families use Augmentative and Alternative Communication (AAC) ^[8]. This can range from simple picture boards to high-tech speech-generating devices.

Assessing Decline vs. True Loss of Skills

It is critical to distinguish between a “relative decline” and a true loss of skills. If your child’s developmental standard scores drop, it may simply mean the gap between their abilities and those of same-age peers is widening, even as they continue to learn. However, a true loss of a previously mastered skill (like losing the ability to speak a word or walk a certain way) is a significant change.

If your child experiences sudden skill loss, new weakness, choking, or staring spells and unusual movements (which could be seizures, affecting some children with KAND), this is not just “expected progression” and requires clinical evaluation ^[8][9].