Fatal encephalopathy after otoneurosurgery procedure with an aluminum-containing biomaterial

Refractory status epilepticus was observed in two patients who underwent vestibular neurectomy. We investigated the relationship with the use of an aluminum containing bone cement during the procedure. Two patients developed focal and thereafter generalized seizures in the late postoperative period of vestibular neurectomy (respectively after 42 and 35 days). A cement (1 g aluminum-calcium fluorosilicate) was used during the procedure to bridge bone defects. Both patients presented cerebrospinal fluid fistula. Investigations excluded common etiologies, in particular infections, and a toxic origin was suspected. Aluminum concentration was determined repeatedly in serum urine, cerebrospinal fluid and retroauricular fistula. The highest aluminum values were respectively in case 1 and 2, 112 and 63 micrograms/L for the cerebrospinal fluid, 495 and 1440 micrograms/L for the fistula, 4.4 and 4.4 micrograms/L in serum. Desferrioxamine was used as chelating agent and aluminum elimination was analyzed in the urine. Status epilepticus became refractory to intensive care therapy. The patients never recovered normal consciousness. Case 1 died 143 days after the procedure and case 2 at 80 days from brain failure. Brain post-mortem examination was obtained in Case 2. Brain aluminum concentration was 2.5 micrograms/g (wet weight) (0.85 micrograms/g in a control non exposed cadaver). The cement (0.2 g) was incubated in vitro (16 h-37 degrees C) with the cerebrospinal fluid of a control patient (cerebrospinal fluid aluminum 8 micrograms/L): aluminum concentration reached 2750 micrograms/L. A close contact between an aluminum containing cement and the cerebrospinal fluid may have resulted in encephalopathy and fatal status epilepticus in these two patients.