Reversible Encephalopathy after Exposure to Glyphosate-Based Herbicide (GBH) in a Patient with ESKD

Introduction: GBH are known to be neurotoxic and often lethal following ingestion. Environmental exposure leads to respiratory and transdermal absorption and prompt renal elimination. However, GBH may be toxic in patients with CKD. Case Description: A 60 year old man with ESKD attributed to diabeties presented to the ER with progressive symptoms of speech apraxia, jerking movements of his upper extremities, and an unsteady gait over the past five days.Fully compliant with CCPD for the past 11 months; recent weekly Kt/V was 1.95. No history of fever, trauma, foreign travel, or substance abuse. Medications: vitamins, calcium acetate, omeprazole, and antihypertensives. He prepared 2 gallons of RoundUp in his garage and sprayed his property for 30-60 minutes wearing a surgical mask 36 hours befor symptoms arose. Exam: 78 kg man with normal vital signs. Oriented to person and place; responded slowly to simple questions without dysarthria or aphasia; positive myoclonic jerkes of extremities, asterixis, and unsteady gait. Rest of neurological and general exam was unremarkable. BUN 43 mg/dL, creatinine 12.8 mg/dL, normal electrolytes; Hemoglobin 13.3 gm/dL, WBC 16,500 /uL, normal differential. Glucose 124 mg/dL, ammonia <9 umol/L TSH 0.78 mIU/mL. CT, MRI/MRA of brain without acute findings. CSF clear with 3 WBC’s, 112 RBC’s, protein concentration 74 mg/dL (15-45), and glucose 78. PCR panel negative for CNS pathogens. Urine drug screen negative. He was empirically given loading doses of IV acyclovir and piperacillin-tazobactam after the LP and then underwent 4 hours of high efficiency hemodialysis for presumed glyphosate neurotoxicity. He was sedated during the LP and line placement but awakened within 30 minutes and manifested myoclonic jerks and slow speech. These symptoms abated throughout the treatment and he was able to speak in complete sentences and drink a cup of water without difficulty by the end of dialysis. A full neurologic recovery was noted the following morning and he walked without assistance. He received another hemodialysis treatment and was discharged to resume nocturnal PD. An assay for serum levels of glyphosate was not available. Discussion: Glyphosate is a glycine based substance with MW 169 daltons. It binds to the NMDA receptor leading to calcium influx and excititoxicity. Heavy routine household exposure in a PD patient led to an encephalopathy consistent with this pathway.