Is Hypertonia hereditary?

Hereditary hyperekplexia is a condition in which affected infants have increased muscle tone (hypertonia) and an exaggerated startle reaction to unexpected stimuli, especially loud noises.

How do you know if you have hyperekplexia?

Arching of the head in conjunction with the startle reaction. Jerking movements after the startle reaction or when trying to fall asleep. Severe muscle tension, which may be most noticeable in infants. Lack of movement or slower than normal movements in babies.

How do you test for hyperekplexia?

Of note, the results of routine blood tests, urinalysis, brain imaging studies, or EEG are usually normal. Hereditary hyperekplexia has different inheritance patterns and is associated with changes ( mutations ) in at least five genes . Genetic testing is available to detect the genetic changes.

What causes an exaggerated startle response?

The exaggerated startle reflex in HPX is probably caused by brainstem pathology. This is supported by the concentration of glycine receptors in the brainstem and spinal cord (Rousseau et al., 2008). In addition, symptomatic excessive startling is usually caused by brainstem damage (Bakker et al., 2006).

What are the symptoms of hypertonia?

Common symptoms include:

• Difficulty moving around.
• Awkward movements.
• Muscle resistance when your child tries to move.
• Muscle spasms.
• Uncontrolled crossing of the legs.

Can hypertonia be misdiagnosed?

A person with dystonic hypertonia can have an involuntary posture due to their inability to stretch the muscles. Dystonic hypertonia is commonly associated with Parkinson’s Disease. (This condition is sometimes misdiagnosed with Sandifer syndrome which also has dystonic movements.)

Is Hyperekplexia treatable?

Hyperekplexia: a treatable neurogenetic disease. Brain Dev. 2002;24:669-74.

What is heightened startle response?

Increased startle responses are excessive or evoked by stimuli that would not be effective in most people. This is identified most easily by loss of habituation. Increased startle reflexes are characteristic of a variety of disorders, including hereditary hyperekplexia.

Does PTSD make you jumpy?

Some people with post-traumatic stress disorder (PTSD) experience heightened anxiety. This may make them more sensitive and overly responsive to stimuli and events in the world around them. This state of increased sensitivity is called hyperarousal.

What does hypertonia look like?

Hypertonia is increased muscle tone, and lack of flexibility. Children with Hypertonia make stiff movements and have poor balance. They may have difficulty feeding, pulling, walking, or reaching.

Is the hyperekplexia Gene X linked or recessive?

Mild intellectual disability may also be observed. In most cases, hyperekplexia is inherited as an autosomal dominant trait, but can also follow autosomal recessive or X-linked inheritance. Mutations in the following genes are associated with the condition: GLRA1, SLC6A5, GLRB, GPHN, and ARHGEF9 (X-linked).

Is the SLC6A5 gene associated with hyperekplexia?

Mutations of the SLC6A5 gene have been associated with hyperekplexia in an autosomal recessive manner. Defects within this gene are hypothesized either to affect the incorporation of the transporter into the cellular membrane or to its affinity for the molecules it transports: sodium ions, chloride ions and glycine.

What happens to an infant with hyperekplexia?

People with HPX demonstrate a magnified startle response to loud sounds or other surprising stimuli. Infants show increased muscle tone, also called hypertonia. After a startle response has occurred, infants will go through a period of rigidity (extreme muscle tension) and are unable to move.

Which is a possible cause of hyperekplexia ( HPX )?

If glycine production is diminished or the receptors sustain damage, the nerve cells can’t regulate their reactivity, and consequently, they respond in an exaggerated way to stimuli. 3  Other potential causes of HPX include an autosomal recessive pattern and a new mutation.