Autopsy Shows Little Brain Damage in Type 2 Patient Who Lived to 61
A man with spinal muscular atrophy (SMA) type 2 in Japan who lived until his 60s was found after his death to have minimal damage in the brain but marked atrophy among the nerve cells of the spinal cord, an autopsy case report showed.
“This report presents unique neuropathological findings of a patient with clinically and genetically confirmed SMA type 2 with a very long disease duration,” the scientists wrote in their report describing the man’s medical history and the autopsy findings.
Titled “Spinal muscular atrophy type 2 patient who survived 61 years: an autopsy case report,” the study was published in Neuropathology and was supported by the Practical Research Project for Rare/ Intractable Diseases of the Japan Agency for Medical Research and Development.
Researchers noted that the male patient started to exhibit muscle weakness and low muscle tone shortly after birth. His intellectual development was normal and he was able to sit up, but was never able to stand or walk.
At age 14, the patient was admitted to a hospital to study at a support school and receive continuing medical care. The hospitalization continued after he had finished schooling.
The patient was started on noninvasive respiratory therapy at age 42 due to breathing problems, and at age 45, he underwent a tracheotomy and started on full-day ventilator therapy. He experienced abdominal distension and difficulty eating starting at about age 60, and was then given nutrition intravenously (into the vein).
At age 61, the man died from a respiratory tract infection.
Notably, “he remained conscious and intellectually clear” throughout the entire course of his disease, the researchers said.
An autopsy was performed about four hours after the patient died. Analyses indicated minimal evidence of damage in the brain. However, there was marked atrophy among the nerve cells in regions of the spinal cord, the team noted. This generally is consistent with SMA, which is caused by the death of motor neurons — the nerve cells that govern movement — which are largely located in the spine.
The researchers noted that the extent of motor neuron loss in this patient was generally less severe than has been reported in other SMA cases.
Genetic testing also was performed following the patient’s death. Results revealed identical mutations in both copies of the SMN1 gene, in which a section of the gene called exon 7 was deleted. The patient also had two copies of SMN2, a related gene that can partially compensate for SMN1, as well as one copy of a gene that appeared to contain portions of both SMN1 and SMN2.
The scientists speculated that these genetic features “might have had an influence on the milder neuropathological findings noted,” but stressed a need for further study into connections between genetics and disease presentation and symptoms in SMA.
The team noted that there are “a low number of autopsy cases describing genetically confirmed SMA type 2 or SMA type 3 available.”