Molar tooth sign (CNS)

Last revised by Ammar Ashraf on 14 Mar 2023

Citation, DOI, disclosures and article data

Citation:

Gaillard F, Ashraf A, Saber M, et al. Molar tooth sign (CNS). Reference article, Radiopaedia.org (Accessed on 18 Apr 2024) https://doi.org/10.53347/rID-8241

DOI:

https://doi.org/10.53347/rID-8241

Permalink:

https://radiopaedia.org/articles/8241

rID:

8241

Article created:

19 Jan 2010, Frank Gaillard ◉ ◈

Disclosures:

At the time the article was created Frank Gaillard had no recorded disclosures.

View Frank Gaillard's current disclosures

Last revised:

14 Mar 2023, Ammar Ashraf ◉

Disclosures:

At the time the article was last revised Ammar Ashraf had no financial relationships to ineligible companies to disclose.

View Ammar Ashraf's current disclosures

Revisions:

12 times, by 9 contributors - see full revision history and disclosures

Systems:

Central Nervous System

Sections:

Signs

Synonyms:

CNS molar tooth sign

The molar tooth sign refers to the appearance of the midbrain in an axial section in which the elongated superior cerebellar peduncles give the midbrain an appearance reminiscent of a molar or wisdom tooth.

It was initially described in Joubert syndrome and related disorders (JSRD) ² but is now recognized to occur in a number of other conditions, e.g. nephronophthisis, hepatic fibrosis, Cogan's syndrome, and pontine tegmental cap dysplasia ⁴.

Molar tooth appearance results from a lack of normal decussation of superior cerebellar peduncular fiber tracts which in turn leads to enlargement of the peduncles, which also follow a more horizontal course ³.

The absence of crossing fibers also leads to a reduction in the anteroposterior diameter of the midbrain and deepening of the interpeduncular cistern ³.

References

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