Urgent - MRI of mental retarded child diagnosed with nonketotic hyperglycinemia

[Hyper1234]

Hi, this is for my friends child who is 17 months. He is at the level of a 5 month old, and severely malnourished at 12 pounds 2 oz. Early testing showed excess levels of glycine (not extremely high at 300, with the normal being up to 247), ammonia and lactate. Because of the high glycine he was diagnosed with the very rare condition of NKH - Nonketotic hyperglycinemia. The glycine level has since then dropped to normal levels. He just went for an MRI with contrast with the following report:

- Marked athropy of both cerebellar hemispheres with atrophic cerebellar vermis associated with large extra-axial retrocerebellar CSF containing cyst. Associated malformation at the level of the ponto-cerebellar junction with molar teeth appearance (arrow).
- No intracerebra focal or diffuse areas of abnormal MR signal. No pathologically enhancing lesions.
- Bilateral symmetrical prominence of the ventrical system
- Preserved gray-white matter differentiation
- Prominent cortical sulci
- No midline shift
- No intracerebral or extra-axial signal of fresh blood density
- Normal posterior fossa structures

Opinion:
Current findings are suggestive of Dandy Walker malformation with molar tooth appearance at the level of the pons suggestive of Joubert syndrome association.

Her mother is asking what this all means. Could there have been a misdiagnosis of NKH? How severe is his retardation, will he ever be able to walk or talk?
And does that fluid cyst seen need to be drained?

He has epilepsy, severe malnutrition, strabismus, poor muscle tone, severe stiffness, vomiting, not gripping objects.
Physical features are light colored smooth hair, protruding tongue, long eyelashes bent outwards at the corners, legs are bent with feet pointing outwards. But there has been no hyperpnea as i understand there would with Joubert syndrome.

Very thankful for your help.

[Hyper1234]

Thank you for your reply

But is it possible that he could have Joubert syndrome? or some other disease which has the molar tooth appearance? should there be any further testing done?

[Christopher R Newey, DO]

Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with a doctor.

Without the ability to examine and obtain a history, I can not tell you what the exact cause of the symptoms is. However I will try to provide you with some useful information.

Dandy Walker malformation is a congenital disorder of the cerebellum and fourth ventricle (i.e, the cerebrospinal fluid space near the cerebellum). The prognosis of this disorder varies according to the severity of the syndrome. Additionally, treatment options, such as surgical drainage of the cyst, is controversial and typically performed if hydrocephalus is present.

It will be important for the child to follow up closely with his neurologist to treat the associated conditions (such as epilepsy) and continue monitoring for complications of Dandy Walker (such as hydrocephalus, cranial nerve palsies, and other features of increased intracranial pressure).

It is difficult to say what the prognosis will be. Most children will have developmental delay in motor and cognitive areas.

Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.