1Tehran University of Medical Sciences, Tehran, Iran
2Fellowship of Clinical toxicologist, Emergency medicine specialist, Medical Toxicology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
3clinical toxicologist, Forensic medicine specialist, Medical Toxicology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
4Clinical toxicologist, Internal medicine specialist, Medical Toxicology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
5Clinical toxicologist, Forensic medicine specialist, Medical Toxicology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
6Clinical toxicologist, Pediatrician, Medical Toxicology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
*Arman Hakemi, MD.Fellowship of Clinical toxicologist, emergency medicine specialist Medical Toxicology Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
Abstract
Background: Phenobarbital, a long-acting barbiturate, is an anticonvulsant whose intoxication can cause CNS depression, drowsiness, confusion and respiratory depression.
Case presentation: We report a case of acute phenobarbital intoxication in a 35-year-old Iranian woman who overdosed on 20 tablets of 200 mg phenobarbital during a suicide attempt. The patient, with no significant medical or family history of medical or psychological illness, presented with a mildly decreased level of consciousness. The patient remained under observation by the medical team. 2 days after her admission to our hospital, the patient experienced a disturbance of her somatosensory modalities as a right-sided hemiparesthesia with a sensory level up to the nipple line. The condition resolved spontaneously without any medical intervention.
Discussion: This case illustrates a peculiar manifestation of phenobarbital intoxication. The mechanism remained unclear. We found no other reports of the mentioned condition in our literature review.
Conclusion: Considering the lack of literature, further investigation to find cases with the same presentation and to discover its pathophysiology seems necessary.
Keywords: phenobarbital, drug toxicity, overdose, somatosensory modality, sensory level
Introduction
Barbiturates can produce all degrees of central nervous system (CNS) depression, from mild sedation to general anesthesia. Some specific types of barbiturates, including phenobarbital, can be used as an anticonvulsant. Barbiturates also have other diagnostic and therapeutic functions; they can be used as sedatives, analgesics, hypnotic withdrawal treatment, emergency treatment of convulsions, and in psychiatry for narcoanalysis and narcotherapy [1]. GABAA receptor-chloride ion channels in the CNS are targets of barbiturates [2]. Phenobarbital, with a half-life of 80-120 hours, is a long-acting barbiturate with oral, intramuscular and intravenous routes of administration, used as an anticonvulsant in the treatment of generalized tonic-clonic seizures, partial seizures and status epilepticus in patients of all ages [1,2].
Severe barbiturate poisoning occurs when more than 10 times the full hypnotic dose is taken at one time. Fatal complications of barbiturate poisoning include coma, hypotension, pulmonary complications such as atelectasis, oedema and bronchopneumonia, and renal failure. Most cases of barbiturate poisoning are the result of deliberate suicide attempts, but some are the result of accidental ingestion by children or drug abusers [2]. The therapeutic anticonvulsant plasma concentration of phenobarbital is 10 to 25 mcg/ml. The dosage of phenobarbital as a daytime sedative in adults is 30 to 120 mg daily in 2 to 3 divided doses; as a bedtime hypnotic, 100 to 320 mg is required; and finally, as an anticonvulsant, the dose is 50 to 100 mg in 2 to 3 divided doses [1]. This case report describes the presentation of a patient with phenobarbital toxicity with an unusual clinical presentation.
Case Presentation
The patient was a 35-year-old Iranian woman who was brought to the emergency department by her family with complaints of phenobarbital toxicity. The patient had taken 20 tablets of 200 mg phenobarbital (4000 mg to simulate) 30 minutes before admission in a suicidal attempt. The patient had obtained these drugs from an illegal pharmacy. The patient had no known medical or surgical history. She had no drug, allergy or social history and didn't mention any psychiatric or medical history in her family. On presentation, her vital signs remained stable and within the normal range, and she had only a slightly depressed level of consciousness with a Glasgow Coma Scale (GCS) score of 13 out of 15. The remainder of the neurological examination and other general investigations were unremarkable.
While the patient remained under observation by the medical team, she developed an unexpected manifestation after 2 days. She began to experience right-sided hemiparesthesia accompanied by a sensory level extending to the nipple line. The patient's light touch and pain modalities were distorted, while other somatosensory modalities such as temperature, pressure and proprioception remained intact. Neurological consultation was requested and electromyography and nerve conduction studies (EMG-NCS) were performed, which were within normal limits. The neurological examination revealed no abnormal findings. Over the course of a week, her paresthesia and skin rash gradually resolved on its own without any specific intervention. There were no sequelae after resolution of this condition, and she was subsequently discharged from the hospital in good general condition.
Discussion
This case raises several intriguing complexities. Firstly the temporary right-sided hemiparesthesia and sensory level at the nipple line present a diagnostic challenge, as no obvious neurological condition was identified during the neurologic consult. The resolution of symptoms without intervention adds another layer of obscurity to this puzzling case. Phenobarbital toxicity is well-documented, primarily affecting the central nervous system and often presenting with symptoms such as drowsiness, confusion, and respiratory depression [1,2]. In this particular case, the mild loss of consciousness and relatively preserved GCS score were consistent with phenobarbital intoxication. However, the absence of severe neurological compromise, despite the overdose, complicates the clinical picture and warrants further investigation.No other reports of distorted sensory modalities or the presence of a sensory level associated with phenobarbital intoxication were found in our literature review. This report can be the beginning of further studies regarding this issue.
conclusion
This case underscores the complexities and uncertainties in toxicology, particularly in the presentation and progression of phenobarbital toxicity. It highlights the need for further research to understand the mechanisms behind the patient's unusual manifestations and spontaneous symptom resolution. Collaboration among toxicologists, pharmacologists, neurologists, and dermatologists is crucial for future diagnoses and treatment strategies for similar cases.
Recommendations
- Further Research: To explore the underlying mechanisms of the patient's symptoms and their resolution.
- Interdisciplinary Collaboration: Encourage collaboration between various specialties to enhance understanding and management of complex toxicological cases.
- Documentation of Unique Cases: Continued documentation and reporting of atypical cases to build a comprehensive knowledge base for better clinical practice.
By sharing this case, we aim to stimulate further interest and research in the field of toxicology, contributing to improved patient care and outcomes.
