A Rare Cause of Rapidly Progressive Acute Motor Axonal Polyradiculoneuropathy (P5.139)

Objective: We describe a case of young patient with acute motor axonal polyradiculoneuropathy secondary to acute intermittent porphyria. Background: Acute intermittent porphyria(AIP) is a rare autosomal dominant metabolic disorder of heme biosynthesiswhich can cause serious neurological manifestations such as acute neuropathy. Design/Methods: Case report Results: A 29 year old woman with no previous medical history was admitted to ICU from an outside facility for management of possible AIDP when she developed ascending paralysis with distal limb paresthesia and intermittent confusion 4 weeks ago; eventually requiring intubation for respiratory failure. Examination was significant for bifacial and neck muscles weakness, quadriplegia, hypotonia and areflexia with relatively preserved sensory modalities. EMG/NCS revealed sub-acute generalized severe motor polyradiculoneuropathy with primary axonal pathology. Imaging studies and CSF analysis were unrevealing. PCR studies for HSV, EMV, CMV, and Western blot for Lyme disease were negative. Serum B12, copper, zinc levels, ANA screen, SPEP, GQ1 b/GM 1 antibodies and urine heavy metal screen were unremarkable. She failed to respond to plasmapheresis treatment for presumed acute motor axonal neuropathy. One week after admission, porphyria screening tests showed highly elevated ALA level at 1134 umol/dl as well as urine porphobilinogen level at 98 umol/l confirming acute porphyria episode. Despite immediate initiation of IV dextrose and hemin treatment, her weakness persisted. She remained dependent on ventilator support and PEG tube for nutrition at three months follow-up. Further genetic testing revealed positive hydroxymethylbilane synthase (HMBS) gene mutation. Conclusions: Our case demonstrates that rapidly progressive acute axonal polyneuropathy is a serious neurological manifestation of porphyria and if not diagnosed early, can lead to irreversible axonal injury and severe disability. This diagnosis should be considered in all cases of acute ascending weakness with minimal sensory deficits when electrodiagnostic features of demyelination are lacking. Disclosure: Dr. Sharma has nothing to disclose. Dr. Kumbham has nothing to disclose. Dr. Sahaya has nothing to disclose. Dr. Sasapu has nothing to disclose. Dr. Gundogdu has nothing to disclose.