Abstract Details

Hyperammonemia resulting in status epilepticus after lung transplant is a rare but rapidly fatal presentation. While more common causes of hyperammonemia include fulminant hepatic failure and decompensated inborn errors of metabolism, in  immunocompromised hosts and particularly in patients with recent lung transplant, opportunistic infection with Ureaplasma urealyticum, Ureaplasma parvum, or Mycoplasma hominis can cause diffuse enzymatic lysis of urea into ammonia. 

On post-operative day (POD) 5 following bilateral lung transplant, a 72-year-old man developed decreased arousal, unresponsiveness, and rhythmic shaking of his left arm quickly identified as status epilepticus. Video EEG revealed myoclonic status epilepticus that was ultimately super-refractory to medical therapy. Initial head CT was normal, and LP was without infectious features, although opening pressure was 25mmHg. Serum ammonia level was found to be 958 µmol/L, but did not respond to treatment with lactulose, rifaximin, or renal replacement therapy until aggressive treatment was added with sodium phenylacetate/sodium benzoate and arginine. Out of a concern for elevated intracranial pressure (ICP), maximum medical therapy with mannitol and hypertonic saline was added, and an ICP monitor was placed. Despite this, serial imaging revealed progressive cerebral edema resulting in bilateral PCA infarcts and, ultimately, the patient’s death on POD11. Ureaplasma urealyticum PCR of BAL fluid later confirmed the diagnosis. Notably, empiric antibiotic therapy with levofloxacin and doxycycline had been started on POD5. 

The differential for new status epilepticus after lung transplant includes common causes such as meningoencephalitis, cerebrovascular disease, and structural neurological disease. In addition, neurologists should hold a high index of suspicion in the lung transplant population for hyperammonemia, particularly from opportunistic infections such as Mycoplasma and Ureaplasma. Early recognition may improve outcomes with rapid initiation of treatment, which includes empiric antibiotics and medical therapy for status epilepticus, elevated ICP, and hyperammonemia.