Diagnosis and management of porphyria
Sir - We read with interest the excellent review article on porphryia
by Thadani et al(1). However the authors do not mention transient cortical
blindness which is a recently reported clinical manifestation of acute
intermittent porphyria (AIP)(2).
Kupferschmidt et al(2) have reported two
cases of AIP in which transient cortical blindness was the presenting
feature followed by flaccid quadriparesis. The T-2 weighted MRI scan
showed reversible hyperintense lesions localised to occipital areas. In
AIP exact pathophysiology of cerebral lesions is not clear. Hypotheses put
forward implicate aminolaevulinic acid, tryptophan, serotonin, segmental
cerebral artery spasm, and segmental demyelination(3).It is speculated by
Kupferschmidt et al (2)
that deficiency of nitric oxide synthase, a emeprotein,leads to deficient
cerebral nitric oxide levels during acute exacerbations of AIP leading to
unopposed cerebral vasoconstriction.
*ajit singh KASHYAP
Department of Medicine,
Armed Forces Medical College,
Pune 411 0450,
1.Thadani H, Deacon A, Peters T. Diagnosis and management of
2.Kupferschmidt H, Bont A, Schnorf H, Landis T, Walter E, Peter J.
Transient cortical blindness and bioccipital brain lesion in two patients
with acute intermittent porphyria. Ann Intern Med 1995; 123: 598-600.
3. Bottomley SS, Lee GR. Porphyria. In Eds: Lee GR, Foerster J,
Lukens, Praskevas F, Greer JP,Rodgers GM, et al. Wintrobe's Clinical
Hematology. 10 th edition, Williams and Wilkins company,
Competing interests: No competing interests