Background: Hereditary Coproporphyria (HCP) is characterized by abdominal pain, neurologic symptoms and
psychiatric disorders, even if it might remain asymptomatic. The pathophysiology of both neurologic and psychiatric
symptoms is not fully understood. Therefore, aiming to evaluate a possible role of brain blood flow disorders, we have
retrospectively investigated cerebral perfusion patterns in Single Photon Emission Computed Tomography (SPECT)
studies in HCP patients.
Materials & Methods: We retrospectively evaluated the medical records of patients diagnosed as being affected by HCP.
A total of seven HCP patients had been submitted to brain perfusion SPECT study with 99mTc-Exametazime
(hexamethylpropyleneamine oxime, HMPAO) or with its functionally equivalent 99mTc-Bicisate (ECD or Neurolite)
according with common procedures. In 3 patients the scintigraphic study had been repeated for a second time after the
first evaluation at 3, 10 and 20 months, respectively. All the studied subjects had been also submitted to an
electromyographic and a Magnetic Resonance Imaging (MRI) study of the brain.
Results: Mild to moderate perfusion defects were detected in temporal lobes (all 7 patients), frontal lobes (6 patients) and
parietal lobes (4 patients). Occipital lobe, basal ganglia and cerebellar involvement were never observed. In the three
subjects in which SPECT study was repeated, some recovery of hypo-perfused areas and appearance of new perfusion
defects in other brain regions have been found. In all patients electromyography resulted normal and MRI detected few
unspecific gliotic lesions only in one patient.
Discussion & Conclusions: Since perfusion abnormalities were usually mild to moderate, this can probably explain the
normal pattern observed at MRI studies. Compared to MRI, SPECT with 99mTc showed higher sensitivity in HCP patients.
Changes observed in HCP patients who had more than one study suggest that transient perfusion defects might be due to a
brain artery spasm possibly leading to psychiatric and neurologic symptomatology, as already observed in patients affected
by acute intermittent porphyria. This observation, if confirmed by other well designed studies aiming to demonstrate a
direct link between artery spasm, perfusion defects and related symptoms could lead to improvements in HCP treatments.