We report a patient presenting with severe muscular impairment and chronic
intestinal pseudo-obstruction (CIP) at the age of eight months. Due to the aggravated symptoms, assisted ventilation, an
ileostomy and
total parenteral nutrition were required. Later on, the patient developed a
locked-in syndrome (Leigh's subacute necrotising encephalomyelopathy) and finally died due to recurrent
pneumonia and
chronic renal failure. The assessment of muscle biopsies revealed a moderate single-fibre type II
atrophy, a variation of muscle fibre calibre with focal fatty degeneration and a decreased reactivity of
cytochrome-c oxidase. Although ragged red fibres had not been found, mitochondrial
enzyme activities were markedly decreased with the lowest residual activity detected for
NADH:Q1 oxidoreductase and
NADH:O2
oxidoreductase (complex I deficiency), thereby confirming the diagnosis of
mitochondrial myopathy. A molecular genetic analysis could not identify known mutations of
mitochondrial DNA. Gastrointestinal full-thickness biopsies revealed myenteric hypoganglionosis of the colon and stomach and
hyperplasia of the submucosal plexus of the ileum. Some of the intestinal smooth muscle cells displayed bulbous protrusions filled with lateralised mitochondria.
Mitochondrial myopathies are known to be associated with a variety of clinical syndromes including CIP. However, in contrast to previous reports in which CIP has been attributed to visceral intestinal
myopathies, the present case is characterised by neuronal intestinal malformations. Therefore, a
mitochondrial myopathy associated with CIP requires a subtle assessment of both the intestinal smooth muscle and the enteric nervous system to identify the underlying pathology.