Your doctor will conduct a general physical exam and assess signs and symptoms that may indicate a neurological disease. A diagnosis of Krabbe disease is based on a series of tests, which may include the following.
A blood sample will be sent to a laboratory to assess the level of GALC enzyme activity. Very low or no GALC activity level may indicate Krabbe disease.
Although the results help a doctor make a diagnosis, they don't provide evidence of how quickly the disease may progress. For example, very low GALC activity doesn't always mean that the condition will advance rapidly.
Your doctor may order one or more imaging tests that can detect the loss of myelin (demyelination) in affected regions of the brain. These may include:
- Magnetic resonance imaging (MRI), a technology that uses radio waves and a magnetic field to produce detailed 3-D images
- Computerized tomography (CT), a specialized X-ray technology that produces 2-D images
Nerve conduction study
A nerve conduction study assesses the rate at which nerves conduct a signal — essentially how quickly they can send a message. A special device measures the time it takes an electrical impulse to travel from one point on the body to another. When myelin is impaired, nerve conduction is slower.
A genetic test may be done with a blood sample to confirm a diagnosis. There are variant forms of the mutated gene that results in Krabbe disease. The particular type of mutation may provide some clues regarding the expected course of the disease.
In some states, a screening test for Krabbe disease is part of a standard set of assessments for newborns. The initial screening test measures GALC enzyme activity. If the enzyme activity is found to be low, follow-up GALC tests and genetic tests are conducted.
The use of newborn screening tests is relatively new. Researchers are still working to understand how best to use these tests, how well the tests lead to an accurate diagnosis and how well they predict the course of the disease.
Studies to date suggest that identifying markers for Krabbe disease before symptoms appear may create a unique treatment window. A treatment procedure called stem cell transplantation may improve the course of Krabbe disease when administered in the first weeks of life.
For infants who have already developed symptoms of Krabbe disease, there is currently no treatment that can change the course of the disease. Treatment, therefore, focuses on managing symptoms and providing supportive care. Interventions may include the following:
- Anticonvulsant medications to manage seizures
- Drugs to ease muscle spasticity and irritability
- Physical therapy to minimize deterioration of muscle tone
- Nutritional support, such as the use of a tube to deliver fluids and nutrients directly into the stomach (gastric tube)
Interventions for older children or adults with less severe forms of the disease may include:
- Physical therapy to minimize deterioration of muscle tone
- Occupational therapy to achieve as much independence as possible with daily activities
Stem cell transplantation
Hematopoietic stem cells are specialized cells that can develop into all of the different types of blood cells in the body. These stem cells are also the source of microglia, specialized debris-eating cells that take up residence in the nervous system. In Krabbe disease, microglia are transformed into toxic globoid cells.
In stem cell transplantation, donor stem cells are delivered into the recipient's bloodstream through a tube called a central venous catheter. The donor stem cells help the body produce healthy microglia that can populate the nervous system and deliver functioning GALC enzymes. This treatment may help restore some degree of normal myelin production and maintenance.
This therapy may improve outcomes in infants if treatment begins before the onset of symptoms — that is, when a diagnosis results from a newborn screening test. Current evidence suggests that stem cell transplantation is most effective when started before an infant reaches 2 weeks of age.
Studies have found that pre-symptomatic children treated with stem cell transplantation may have slower disease progression and improved quality — and length — of life, compared with children who don't receive stem cell transplantation before symptoms develop. However, infants who have stem cell transplants before symptoms appear still develop significant difficulties with speech, walking and other motor skills during childhood.
Older children and adults with mild symptoms of Krabbe disease also may benefit from this treatment. As with infants, the severity of symptoms at the time of stem cell transplantation affects treatment outcomes.
Coping and support
Organizations that offer support, educational resources, networking opportunities and services to families dealing with Krabbe disease include the following:
United Leukodystrophy Foundation
Preparing for your appointment
In some cases, Krabbe disease is diagnosed in newborns with screening tests before symptoms appear. Conversations with your child's doctor and a specialist in nervous system disorders (neurologist) would begin as soon as a diagnosis is confirmed. In most cases, however, the onset of symptoms triggers a search for possible causes.
It's important to take your child to all regularly scheduled well-baby visits and annual appointments during childhood. These visits are an opportunity for your child's doctor to monitor your child's development in key areas, including:
- Muscle tone
- Muscle strength
- Age-appropriate motor skills
- Sensory abilities — vision, hearing and touch
Questions you should be prepared to answer during regular checkups might include the following:
- What concerns do you have about your child's growth or development?
- How well does he or she eat?
- How does your child respond to touch?
- Is your child reaching certain milestones in development, such as rolling over, pushing up, sitting up, crawling, walking or speaking?
Preparing for other doctor visits
If you're seeing your doctor because of the recent onset of symptoms, you'll likely start by seeing your general practitioner or your child's pediatrician. After an initial evaluation, your doctor may refer you to a neurologist.
Be prepared to answer the following questions about your symptoms or on your child's behalf:
- What signs or symptoms have you noticed? When did they begin?
- Have these signs or symptoms changed over time?
- Do you notice any changes in your child's attentiveness?
- Has your child had a fever?
- Have you noticed unusual or excessive irritability?
- Have you noticed changes in eating habits?
Questions especially for older children or adults may include:
- Has your child's school performance changed?
- Have you had difficulty with normal tasks or job-related work?
- Are you or is your child being treated for other medical conditions?
- Have you or your child recently begun a new medication?