The Curious Case of the Woman with No Cerebellum
Not sure how many of you have read about this by now, but it is such an amazing finding I decided to write about it (even though I retweeted this yesterday).
This study is a clinical case report of a living patient with cerebellar agenesis, an extremely rare condition characterized by the absence of the cerebellum. The cause is currently unknown, there are limited reported cases of complete cerebellar agenesis, and most of what we know about the condition comes from autopsy reports instead of living patients. Moreover, the condition is difficult to study because most individuals with complete primary cerebellar agenesis are infants or children with severe mental impairment, epilepsy, hydrocephaly and other gross lesions of the CNS. The fact that this woman is alive and has a somewhat “normal” life is ground-breaking and presents a unique opportunity to study the condition.
The patient described in the study is 24 years old. She has mild mental impairment and moderate motor deficits. For example, she is unable to walk steadily and commonly experiences dizziness/nausea. She also has speech problems and cannot run or jump. However, she has no history of neurological disorders and even gave birth without any complications.
Importantly, as shown above, CT and MRI scans revealed no presence of recognizable cerebellar structures. Just look at that dark sport towards the back of the brain! In addition to these findings, magnetic resonance angiography also demonstrated vascular characteristics of this patient consistent with complete cerebellar agenesis- meaning that the arteries that normally supply this area were also absent bilaterally. How crazy is that? Futhermore, diffusion tensor imaging indicated a complete lack of the efferent and afferent limbs of the cerebellum.
Given that the cerebellum is responsible for both motor and non-motor functions, these results are pretty amazing. How can the brain compensate for such a heavy blow to its architecture and connectivity? According to the authors of the study:
This surprising phenomenon supports the concept of extracerebellar motor system plasticity, especially cerebellum loss, occurring early in life. We conclude that the cerebellum is necessary for normal motor, language functional and mental development even in the presence of the functional compensation phenomenon.