Ankle Clonus in 2 Months Old

by Lindsay
(Denver )

My son, born at 30 weeks, is 9.5 weeks old but only 2 days adjusted. He had about 20 beats of clonus on his left ankle and only about 6-8 beats on his right.

It happened yesterday after I bathed him and was putting lotion on him. I was able to repeat it several times in both the ankles.

He also has jaw clonus when he cries or is about to cry. Should I be talking to a neurologist about this?

The Expert, Ren Chats Answers

Yes, you should consult a pediatric neurologist.
It is because the characteristics of the ankle clonus you described are

• Sustained of 20 beats

• It could be reproduced, which shows that the clonus is persistent.

• It is bilateral; even though the other side had fewer beats.

I do not know why your baby was born at 30 weeks of gestation.
But infants born prematurely could have an underlying cause such as:

1. Maternal stress, fatigue or infection.

2. Second hand smoke exposure.

3. Alcohol consumption by the mother during pregnancy.

4.Mothers who drink alcohol during first year of childbirth. and more.

Ongoing rapid brain growth and development during fetal growth extends well through the third year of life. Aforementioned environmental factors therefore have vital negative influence on neurodevelopment of infants.
Premature babies and low birth weight infants are also more prone to
child birth related insults.

Sustained ankle clonus

Ankle clonus of more than 10 beats indicate neuro-developmental disorder. Jitteriness and occasional ankle twitching are known to be normal in newborns. In premature babies such movements do continue for a longer period.
How long should it be considered to be within normal limits is Not well defined.

However, it has been noted that most ankle clonus of more than 10 beats, anytime during the first 365 days of life, could be associated with some neurological compromise.

These infants therefore need several regular close clinical follow ups for early detection and timely intervention of possible neuro-developmental disorder.

Possible causes of ankle clonus during infancy:

Cerebral palsy

• Cerebral vascular accidents

• Upper motor neuron lesion


• Spinal cord injury.

• Infections: Congenital, meningitis or encephalitis.

What is ankle clonus?

Ankle clonus is not the same as jitteriness in newborns.

• Clonus is a Greek word that means violent confused movements and ankle clonus is defined as abnormal neuromuscular activity that presents as sustained series of involuntary, rhythmic, muscular contractions and relaxations in rapid succession, the duration of which is highly variable; few seconds to several minutes.

Ankle clonus indicates upper motor neuron lesion. In infants, if it persists beyond 3 months of age it is taken as a sign of subsequent neuro-developmental disorder, most common being spastic cerebral palsy.


Prognosis of infants with ankle clonus within the first year of life: by Futagi Y, Otani K, Goto M.; Division of Pediatric Neurology, Osaka Medical Center, Japan; Brain Dev. 1997 Jan;19(1):50-4.

Related pages of interest:

1. Is Jitteriness in Newborn Babies Abnormal?

2. Ankle Twitching

3. Jitteriness at 3 Months

4. Strange Behavior of 10 Weeks Old Infant

5. Ankle Clonus in 2 Months Old

6. Facial Twitching in 2 Month Old Baby

7. Shivering of Head and All Body While Feeding During Sleep
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