Autonomic neuropathy in acute intermittent porphyria.

Abstract

SUMMARY Autonomic function was assessed in subjects with acute intermittent porphyria and age-and sex-matched controls using five different bedside tests of cardiovascular reflexes. During the acute attack both parasympathetic and sympathetic tests were impaired, but subsequently improved during remission. Early parasympathetic dysfunction was also detected during remission and in latent asymptomatic acute intermittent porphyria.Acute intermittent porphyria is an autosomal dominant inborn error of metabolism characterised by a partial deficiency in the activity of the haem biosynthetic enzyme, porphobilinogen deaminase (PBG). Consequently the porphyrin precursors delta-aminolaevulinic acid (ALA) and porphobilinogen (PBG) accumulate in blood and are excreted in excessive amounts in the urine.' 2The clinical manifestations of acute intermittent porphyria have been attributed to a widespread neurological dysfunction caused by the block in haem biosynthesis.34 Abdominal pain is the commonest and often the most troublesome symptom which occurs in more than 90% of cases.5 It has been explained on the basis of splanchnic autonomic dysfunction, thus providing a mechanism for the intestinal dilatation and stasis occasionally noted radiologically and at laparotomy in patients suffering from an acute attack.6 Indeed, many of the accompanying features of an acute attack are suggestive of autonomic neuropathy; namely, the inappropriate sinus tachycardia, labile hypertension, postural hypotension, excessive sweating, severe vomiting, constipation and occasional diarrhoea and sphincteric bladder problems.5 78 Ridley et al have reported that tachycardia invariably preceded the development of peripheral neuropathy and respiratory paralysis, and they postulated that the tachycardia of porphyria might be due to autonomic cardioneuropathy.5 The transient and labile hypertension which commonly accompanies the acute attack has also been given a neurogenic explanation follow-

The neurologic manifestations of the acute porphyrias

“…Autonomic testing demonstrates both parasympathetic and sympathetic dysfunction during an acute attack that improves with resolution of the episode. 26 This correlates with autopsy studies, which have demonstrated demyelination and axonal degeneration of the vagus nerve and decreased density and chromatolysis of sympathetic ganglia cells. 27 …”

Desfluran bei akute intermittierender Porphyrie

“…B. in autonomen Ganglien,spinalen Vorderhornzellen,peripheren Neuronen, Kernen des Stammhirns, im Kleinhirn, in Schwann-Zellen und Myelinscheiden nachgewiesen werden können [1,3,5,26,30],wird in einer direkten Schädigung von Nervenzellen gesehen. Der histopathologische Befund zeigt meist eine Störung des Aufbaus der Myelinscheide sowie eine Vakuolisierung und einen Abbau der Axone in autonomen und peripheren Nerven [25].…”

Acute intermittent porphyria and Caesarean delivery

“…Central nervous system involvement may present as seizure activity, depression or as an acute organic brain syndrome (confusion, delusions and hallucinations). [4][5][6][7] …”