Aging is associated with a progressive reduction of infratentorial neural tissue volumes, particularly affecting the cerebellum, accompanied by a relative expansion of PCF-CSFv, with males demonstrating larger infratentorial structures than females throughout adulthood.
Key Findings
Results
Cerebellar volume showed a progressive decline with increasing age in stroke patients.
Cerebellar volume declined from 136 cm³ (IQR 123.6–147.2) in younger age groups to 115.2 cm³ (IQR 107.4–131.1) in older age groups (p < .001).
The study included 1,280 adult subjects from 11 university hospitals in Germany.
Data were collected retrospectively from patients who underwent neuroimaging for suspected or confirmed cerebellar stroke.
Segmentation and volumetric analysis were performed primarily using Brainlab software (Brainlab AG, Munich, Germany).
Results
Posterior cranial fossa cerebrospinal fluid volume (PCF-CSFv) increased with age, indicating age-related expansion of infratentorial cerebrospinal fluid spaces.
The increase in PCF-CSFv was statistically significant (p < .001).
This expansion accompanied the progressive decline in cerebellar and brainstem volumes.
The finding suggests a compensatory or passive enlargement of CSF spaces as neural tissue volume decreases with age.
Results
Males exhibited larger posterior cranial fossa, cerebellar, and brainstem volumes than females across most age groups.
Sex-related differences in PCF, cerebellar, and brainstem volumes remained statistically significant after Holm-Bonferroni correction (all p-corrected < 0.001).
PCF-CSFv did not differ significantly between females and males (p-corrected = 0.438).
These pronounced sex-related volumetric differences persisted throughout adulthood.
Results
Posterior cranial fossa and brainstem volumes demonstrated significant age-related changes in addition to cerebellar volume changes.
PCF, cerebellar, and brainstem volumes all showed significant age-related changes (p < .001).
The study evaluated both MRI- and CT-based volumetric analysis across 11 university hospitals.
In selected centers, volumetric calculations were performed using the standard method according to local protocol rather than Brainlab software.
Conclusions
The study provides normative volumetric data for the posterior cranial fossa and its neural structures in an adult stroke patient population.
The retrospective, multicenter study included 1,280 adult subjects from 11 university hospitals in Germany.
The authors state these findings 'provide robust normative data that may aid in the interpretation of PCF pathology in clinical and research settings.'
Prior data on volumetric changes of the PCF and its contents in the adult population were described as limited.
The study focused on adults with suspected or confirmed cerebellar stroke, representing a specific clinical population.
What This Means
This research suggests that the brain structures housed within the lower back portion of the skull — particularly the cerebellum (which coordinates movement and balance) and the brainstem — shrink progressively as people age. Studying over 1,200 adult stroke patients from 11 hospitals across Germany, researchers found that the cerebellum decreased in volume from about 136 cubic centimeters in younger adults to about 115 cubic centimeters in older adults. As brain tissue volume decreased, the space filled with cerebrospinal fluid (the protective liquid surrounding the brain) increased to compensate, effectively filling the space left behind by shrinking neural tissue.
The study also found consistent differences between males and females: men had larger posterior cranial fossa, cerebellar, and brainstem volumes than women across virtually all age groups, and these differences were statistically robust even after accounting for multiple comparisons. Notably, the amount of cerebrospinal fluid in this region did not differ significantly between sexes, suggesting the sex differences are specific to neural tissue size rather than fluid spaces.
This research matters because it establishes reference data — what 'normal' looks like across different ages and sexes — for a part of the brain that is relatively understudied compared to the rest. Clinicians and researchers examining patients with conditions affecting this region (such as cerebellar stroke, tumors, or other disorders) may be able to use these normative values to better distinguish age-expected changes from disease-related changes, potentially improving diagnosis and treatment planning.
Rafaelian A, Cantré D, Dubinski D, Baki E, Beutel T, Dinc N, et al.. (2026). Age-Related Volumetric Changes of the Posterior Cranial Fossa and its Structures in Stroke Patients.. Cerebellum (London, England). https://doi.org/10.1007/s12311-026-02082-3