Seizures Following Self-Medication With Colloidal Silver: A Case Report

Case Presentation

The patient was a 70 year old man who was sent to the emergency department (ED) due to a concern for stroke after initially presenting to an urgent care clinic where he had a witnessed seizure.

His past medical history included arthritis, coronary artery disease, gout, acute myocardial infarction, hearing loss, chronic kidney disease, hypertension, gastric reflux, erectile dysfunction, quadruple coronary artery bypass grafts, and a transient ischemic attack without residual effects 10 years prior to presentation.

The patient went to urgent care after experiencing difficulty using an eating utensil at home which was accompanied by expressive aphasia. This had resolved by the time he presented to urgent care, but then while being examined there the expressive aphasia returned along with right-sided deficits, followed by a seizure which was initially focal but then generalized. The patient received 1 milligram of lorazepam and was sent to the ED.

Upon arrival in the ED, the patient was hypertensive with a blood pressure of 195/95 mmHg and was acutely encephalopathic. Due to a concern for an intracranial hemorrhage, he was intubated and sent for an emergent head computed tomography scan, which proved unremarkable. Laboratory findings from the ED were notable for an anion gap of 15 mmol/L (3-11 mmol/L), serum creatinine of 1.37 mg/dL (0.7-1.3 mg/dL), phosphorus 2.1 mg/dL (2.4-5.1 mg/dL), aspartate aminotransferase 39 U/L (<35 U/L), creatine kinase 206 U/L (46-171 U/L), and leukocytes 13.59 K/uL (3.8-11 K/uL). A toxicology screen drawn in the ED was negative except for benzodiazepines (which the patient had received prior to arrival in the ED).

A lumbar puncture was obtained against the possibility of an infectious encephalopathy, and the patient was sent to the critical care unit (CCU) with consults to pulmonology and neurology, at which time his differential diagnosis included cerebrovascular accident (CVA), malignancy with central nervous system (CNS) metastases, encephalitis, meningitis, hypertensive encephalopathy, or other cause of metabolic encephalopathy, with the pulmonologist noting less likely etiologies included temporal arteritis, CNS vasculitis, or cardioembolic disease. Despite a low grade fever of 38.1°C and mild leukocytosis, the risk of infection was felt to be low due to the negative cerebrospinal fluid (CSF) findings (including viral panel) from samples collected in the ED, therefore antibiotics were held upon admission to the CCU.

Magnetic resonance imaging (MRI) of the brain without contrast was conducted on Day 2, and per the neurologist’s review was without clear structural abnormality other than hippocampal sclerosis. An electroencephalogram (EEG) was done on Day 3 while the patient was comatose and intubated, with results showing an abnormal EEG study due to severely generalized background slowing, consistent with global encephalopathy, and no obvious epileptic seizure focus. CSF studies proved negative.

During the patient’s stay in the CCU, his wife eventually revealed that he had been taking colloidal silver in the weeks leading up to his presentation. The silver was apparently prepared by a relative according to instructions in a book titled Colloidal Silver: The Natural Antibiotic by Werner Kühni, which describes a method for preparation using low-voltage electrolysis. This method involves a direct current and silver electrodes, causing silver ions (colloidal particles) to be emitted from the anode: “Depending on the conditions, running this process for approximately 10 to 50 minutes will yield 200 mL of colloidal silver with a concentration of approximately 3 to 50 ppm (part-per million) in steam-distilled water.” The patient’s wife noted that he had been partaking of a dose of 1 ounce of this preparation per day.

On Day 16, laboratory studies were sent for trace and heavy metals, which returned negative for lead, mercury, and arsenic, but with a silver level of 15.5 ng/mL (<1 ng/mL).

Despite being complicated by ventilator-associated pneumonia, the patient’s respiratory status continued to improve over time. Sedation was weaned on Day 14, and the patient was extubated on Day 15. The patient demonstrated continued mental status improvement and was able to tolerate dietary advancement up to a general diet by the time of discharge. His workup for seizures remained unrevealing. The patient was discharged on oral levetiracetam on Day 22.

Outcome and Follow Up

Two months after discharge, the patient was tolerating the levetiracetam without any further seizure occurrence.

Discussion

Our patient’s Naranjo Adverse Drug Reaction Probability Scale score was 7, indicating a probable adverse drug reaction to the colloidal silver. Additionally, no other likely diagnosis presented itself to challenge the colloidal silver as the reason for the patient’s hospitalization.

Extant published cases of neurological toxicity due to silver are rare. Stepien et al ¹ reported a case of a patient with myoclonic seizures in the setting of colloidal silver ingestion over a period of 4 years; serum silver was 67.7 ng/mL. Mirsattari et al ² reported a case of myoclonic status epilepticus following daily ingestion of colloidal silver over a period of 4 months; plasma silver was 4.5 ng/mL. Tobarran and Hieger ³ reported a case of acute toxicity with neurological manifestations including lethargy, slurred speech, and altered mental status within 36 hours after ingesting 473 mL of a 2838 ppm colloidal silver solution; the silver level was 75 ng/mL. Naddaf et al ⁴ reported a case of peripheral neuropathy in the setting of a woman who had taken colloidal silver for several months; serum silver was 162 ng/mL. Lastly, Ohbo et al ⁵ reported a case of a woman who had taken silver pills in a dose of approximately 20 mg per day for 40 years; she presented with convulsive seizures and a serum silver of 12 ng/mL.

The majority of the cases described in the literature documented patients presenting with seizures after months or years of ingestion. In contrast, our patient developed a seizure within weeks of ingestion of colloidal silver, a much more rapid presentation than generally reported in the literature. It appears that neurological toxicity may occur at widely varying serum levels of silver, the cases described above note silver levels ranging from 4.5 to 162 ng/mL. Additionally, onset times seem to vary from acute toxicity occurring within hours (Tobarran and Hieger) to decades (Ohbo). It is difficult to compare and contrast these cases given their apparent heterogeneity, however perhaps as more cases are reported, patterns may emerge. At this time it appears that neurological manifestations of silver toxicity are indeed rare, but present a risk, and clinicians should be aware of this potentially dangerous side effect in patients who are ingesting colloidal silver.

As noted by Kumar and Goia, ⁶ “The unique properties of silver have been known and exploited by humans since antiquity,” including its antibacterial and perhaps even antiviral properties. Colloidal silver has now gained some attention against the backdrop of the novel coronavirus (SARS-CoV-2) pandemic, with a proliferation of products with claims of potential cure. ⁷ The FDA has stated that colloidal silver is not safe or effective for treating any disease or condition, and the FDA and Department of Justice have taken action against firms peddling silver products purporting to treat or cure Covid-19.^{8 -10} Given the proliferation of silver-containing products which may be associated with unfounded claims regarded safety and efficacy, the potential for CNS toxicity should be considered.