Patient Overview
The patient: A 44-year-old man from France.
The symptoms: For two weeks leading up to his doctor’s visit, he experienced mild weakness in his left leg. His medical history was mostly unremarkable, aside from an incident at six months old when a shunt was placed in his head to help with an unknown cause of fluid buildup in the brain. This shunt was removed when he was 14 years old.
What happened next: When the man disclosed his leg weakness, doctors conducted CT and MRI scans of his head, alongside neuropsychological assessments. These tests indicated that his IQ was 75, well below the average of 100.
The diagnosis: The medical team concluded that he had a brain at least half the typical size. The scans also showed a significant fluid accumulation in his brain, which was likely compressing the tissue, resulting in only a thin layer of brain material against his skull. The ventricles — or fluid-filled cavities in the brain — were notably dilated, which likely contributed to his leg weakness.
The treatment: Doctors drained the excess fluid from his skull, allowing the man to regain some strength in his leg. According to a case report published in a medical journal, a new shunt was then inserted, and a few weeks later, his neurological evaluations returned to baseline. However, the findings from the neuropsychological testing didn’t change, keeping his IQ relatively stable.
What makes the case unique: Compared to our evolutionary relatives, humans have relatively large brains, which is associated with enhanced cognitive skills and language abilities. The reasons behind this size increase are still somewhat unclear, though a mix of environmental and dietary influences likely played a role.
Interestingly, human brains continue to grow significantly throughout a person’s life, often resulting in a brain size much larger than at birth. In this case, while one might expect deficits due to a smaller-than-average brain, the man was functioning as a civil servant without any apparent issues — until his leg weakness developed, that is. Without that symptom, his condition might have remained unnoticed.
