Multifocal myoclonus induced by trimethoprim-sulfamethoxazole therapy in a patient with nocardia infection

The clinical heterogeneity of drug-induced myoclonus: an illustrated review

A wide variety of drugs can cause myoclonus. To illustrate this, we first discuss two personally observed cases, one presenting with generalized, but facial-predominant, myoclonus that was induced by amantadine; and the other presenting with propriospinal myoclonus triggered by an antibiotic. We then review the literature on drugs that may cause myoclonus, extracting the corresponding clinical phenotype and suggested underlying pathophysiology. The most frequently reported classes of drugs causing myoclonus include opiates, antidepressants, antipsychotics, and antibiotics. The distribution of myoclonus ranges from focal to generalized, even amongst patients using the same drug, which suggests various neuro-anatomical generators. Possible underlying pathophysiological alterations involve serotonin, dopamine, GABA, and glutamate-related processes at various levels of the neuraxis. The high number of cases of drug-induced myoclonus, together with their reported heterogeneous clinical characteristics, underscores the importance of considering drugs as a possible cause of myoclonus, regardless of its clinical characteristics.

Acute movement disorders in the medical setting

Objective Psychosomatic medicine psychiatrists are often tasked with the evaluation and treatment of complex neuropsychiatric states which may be motoric in phenotype. Little energy has been dedicated to understanding acute movement disorders in the hospital environment. Method Recognizing the importance of frontal-subcortical (corticostriatothalamocortical) circuitry and basal ganglia structures, we present a case series of acute movement disorder phenotypes resulting from underlying medical conditions, commonly-administered medications, or the interaction of both. We organize these scenarios into neurodegenerative disorders, primary psychiatric disorders, neuroinflammation, and polypharmacy, demonstrating a clinical example of each followed by background references on a variety of clinical states and medications contributing to acute movement disorders. In addition, we offer visual illustration of implicated neurocircuitry as well as proposed neurotransmitter imbalances involving glutamate, gamma aminobutyric acid, and dopamine. Furthermore, we review the various clinical syndromes and medications involved in the development of acute movement disorders. Results Acute movement disorder's involve complex interactions between frontal-subcortical circuits and acute events. Given the complexity of interactions, psychopharmacological considerations become critical, as some treatments may alleviate acute movement disorders while others will exacerbate them. Conclusion Integrating underlying medical conditions and acutely administered (or discontinued) pharmacological agents offers an interactional, neuromedical approach to acute movement disorders that is critical to the work of psychosomatic medicine.

Reversible myoclonus, asterixis, and tremor associated with high dose trimethoprim-sulfamethoxazole: a case report

CASE DIAGNOSIS

Reversible myoclonus, tremor, and asterixis induced by high dose trimethoprim-sulfamethoxazole.

CASE DESCRIPTION

The patient was a 66-year-old male with T9 AIS(1) C quadriplegia secondary to spinal cord compression by a tumor due to large B cell lymphoma. Subsequent to tumor resection and chemotherapy, the patient was discovered to have Pneumocystis jiroveci pneumonia (PJP). Once started on high dose trimethoprim-sulfamethoxazole (TMP-SMX) therapy (15.6 mg/kg/day of trimethoprim) for the treatment of PJP, he displayed bilateral upper extremity myoclonic jerks at rest, asterixis, and postural tremor. Symptoms resolved once TMP-SMX therapy was discontinued.

DISCUSSION

Myoclonus, asterixis, and tremor have been linked to high dose TMP-SMX therapy as a toxic side effect. Our patient's symptoms did improve with levetiracetam therapy, but did not fully resolve until TMP-SMX was discontinued.

CONCLUSIONS

This is thought to be the first reported case of reversible myoclonus, tremor, and asterixis induced by high dose TMP-SMX in the spinal cord injury population. Early recognition of TMP-SMX induced complications were of key importance as they negatively impacted the rehabilitation process. We also recommend consideration of symptomatic treatment with levetiracetam for the duration of required TMP-SMX therapy as it appeared to mitigate the severity of our patient's movement disorders.

Cotrimoxazole - optimal dosing in the critically ill

The optimum dosage regimen for cotrimoxazole in the treatment of life threatening infections due to susceptible organisms encountered in critically ill patients is unclear despite decades of the drug's use. Therapeutic drug monitoring to determine the appropriate dosing for successful infection eradication is not widely available. The clinician must utilize published pharmacokinetic, pharmacodynamic, and effective inhibitory concentration information to determine potential dosing regimens for individual patients when treating specific pathogens. Using minimum inhibitory concentrations known to successfully block growth for target pathogens, the pharmacokinetics of both trimethoprim and sulfamethoxazole can be utilized to establish empiric dosing regimens for critically ill patients while considering organ of clearance impairment. The author's recommendations for appropriate dosing regimens are forwarded based on these parameters.

Tetrahydrobiopterin biosynthesis as an off-target of sulfa drugs

The introduction of sulfa drugs for the chemotherapy of bacterial infections in 1935 revolutionized medicine. Although their mechanism of action is understood, the molecular bases for most of their side effects remain obscure. Here, we report that sulfamethoxazole and other sulfa drugs interfere with tetrahydrobiopterin biosynthesis through inhibition of sepiapterin reductase. Crystal structures of sepiapterin reductase with bound sulfa drugs reveal how structurally diverse sulfa drugs achieve specific inhibition of the enzyme. The effect of sulfa drugs on tetrahydrobiopterin-dependent neurotransmitter biosynthesis in cell-based assays provides a rationale for some of their central nervous system-related side effects, particularly in high-dose sulfamethoxazole therapy of Pneumocystis pneumonia. Our findings reveal an unexpected aspect of the pharmacology of sulfa drugs and might translate into their improved medical use.

Probable trimethoprim/sulfamethoxazole-induced higher-level gait disorder and nocturnal delirium in an elderly man

OBJECTIVE

To report a case of probable trimethoprim/sulfamethoxazole (TMP/SMX)-induced higher-level gait disorder (HLGD) and nocturnal delirium in an elderly patient on high-dose oral therapy.

CASE SUMMARY

An 82-year-old man with a recent history of depression became comatose following an overdose of escitalopram and oxazepam. He was admitted, ventilated for 7 days in the intensive care unit, and treated with piperacillin/tazobactam and cefepime for aspiration pneumonia. Following discharge to a medical ward, respiratory symptoms persisted and imaging confirmed pulmonary abscesses. Stenotrophomonas maltophilia was isolated from sputum and, on day 15, TMP/SMX 800 mg/160 mg 1 tablet every 12 hours was initiated. On day 35, the dose was increased to 800 mg/160 mg 2 tablets every 12 hours. By day 37, the patient was unsteady when attempting to stand. From day 40, he was noted to have features of HLGD with gait ignition failure, poor balance, and frequent falls. His other medications at this time were thiamine 100 mg daily, multivitamin 1 tablet daily, omeprazole 20 mg every 12 hours, and modified-release venlafaxine 150 mg daily. Investigation did not reveal any cause for his acute gait disturbance. TMP/SMX was stopped on day 48 and, by day 51, the patient's gait had returned to normal.

DISCUSSION

Neuropsychiatric adverse reactions with TMP/SMX have been infrequently reported. The Naranjo probability scale indicated that TMP/SMX was the probable cause of HLGD in this patient.

CONCLUSIONS

At time of writing, this was the first reported case of HLGD associated with TMP/SMX. Clinicians should consider this adverse reaction as a potential cause of HLGD, especially in the elderly and those with malnutrition and hepatic or renal dysfunction.

Memantine-Induced Myoclonus and Delirium Exacerbated by Trimethoprim

Objective:

To report a case of myoclonus and delirium seen in a patient taking a combination of memantine and trimethoprim.

Case Summary:

A 78-year-old woman was admitted to the medical center in October 2007 with rapid deterioration of Alzheimer's dementia and progressive myoclonus. In 2003, donepezil 5 mg/day had been initiated and her disease slowly progressed. In 2006, memantine 10 mg twice daily was added. Myoclonic activity and delirium were noted in 2007 when a urinary tract infection (UTI) was treated with double-strength trimethoprim/sulfamethoxazole (TMP/SMX 160 mg/800 mg). After discontinuation of TMP/SMX, the patient's condition returned to baseline level. Several weeks later, trimethoprim 100 mg daily was added for UTI prophylaxis. Within weeks, spontaneous generalized myoclonic activity resumed to the extent that the patient was unable to walk. She became increasingly delirious. A week before admission, levodopa/carbidopa 250 mg/100 mg was added for presumptive restless legs syndrome and the patient became extremely delirious and combative, requiring hospitalization. Because of the striking similarity of dose-related toxicities reported with amantadine, a slightly different aminoadamantane, memantine was withheld. Trimethoprim was discontinued due to a likely interaction with memantine. Donepezil and famotidine were withheld due to questions of therapeutic necessity. After 3 days, the myoclonus had completely resolved and the patient was no longer agitated or combative during the remainder of her hospitalization. She was cooperative and ambulatory and was discharged.

Discussion:

Memantine is cleared primarily through the kidneys and should be renally dosed. Drugs that interfere with elimination—that is, other drugs utilizing the organic cation transporter-2 in the tubule, such as trimethoprim, metformin, or imipramine—may lead to drug accumulation. Our patient, who had impaired renal function, developed severe myoclonus and delirium after trimethoprim was added to therapy with memantine. As there were no reports of myoclonus and delirium with this drug combination and because of the structural, pharmacologic, and pharmacokinetic similarities between the aminoadamantanes memantine and amantadine, we researched similar dual adverse effects reported with amantadine. Amantadine has led to the same adverse effects noted in our patient, not only in patients with renal impairment, but also in one patient when trimethoprim was added to a stable dose of amantadine.

Conclusions:

This is the first reported case of a drug interaction between memantine and trimethoprim, which resulted in clinically significant myoclonus and delirium. Clinicians should be aware of this potential interaction, since there have been reports of this adverse effect with the use of amantadine. Because memantine chemically and pharmacologically resembles amantadine, it is quite possible that their toxicities are similar.

Case reports and the fight against cancer

Some of the earliest case reports describing individual patients afflicted with cancer can be traced all the way back to the papyrus records of Ancient Egyptian medicine of approximately 1600 B.C.. Throughout the centuries physicians have continued the practice of writing case reports. Case reporting has provided significant advances in the knowledge of cancer on several fronts. It is without question that case reports do not replace well designed randomized clinical trials in advancing medical knowledge about cancerous diseases. However, case reports have their unique role in evidence-based medicine and often constitute the first line of evidence. This editorial reviews the many useful aspects of case reports and describes specific reports known to have revolutionized cancer management. Journal of Medical Case Reports is committed to publish well written case reports from around the world and be a source of inspiration for clinicians and scientists about newer research directions.

Tremors and chorea induced by trimethoprim-sulfamethoxazole in a child with Pneumocystis pneumonia

A 1.5-year-old girl developed high frequency tremors and chorea after receiving a dose of 120 mg/kg/d trimethoprim-sulfamethoxazole (TMP-SMX) for the treatment of Pneumocystis pneumonia. The child was human immunodeficiency virus-negative but immunocompromised because of prolonged immunosuppressive therapy. These symptoms disappeared 3 days after TMP-SMX was discontinued. Pediatricians should be aware of tremors and chorea among the potential adverse effects of high doses of TMP-SMX.