Choreoathetosis during phenytoin treatment

Pharmacotherapy for Focal Seizures in Children and Adolescents

Focal-onset seizures are among the most common forms of seizures in children and adolescents and can be caused by a wide diversity of acquired or genetic etiologies. Despite the increasing array of antiseizure drugs available, treatment of focal-onset seizures in this population remains problematic, with as many as one-third of children having seizures refractory to medications. This review discusses contemporary concepts in focal seizure classification and pathophysiology and describes the antiseizure medications most commonly chosen for this age group. As antiseizure drug efficacy is comparable in children and adults, here we focus on pharmacokinetic aspects, drug-drug interactions, and side effect profiles. Finally, we provide some suggestions for choosing the optimal medication for the appropriate patient.

Phenytoin Induced Chorea: A Rare Adverse Effect of the Drug

BACKGROUND

Dyskinetic neurological diseases are common presentations of adverse reaction to many therapeutic agents. Phenytoin, a widely used age-old antiepileptic drug has been reported to cause dyskinesias, a rare Adverse Drug Reaction (ADR) in adults with toxic therapeutic serum level. When the drug is used in combination with other drugs which augments free drug level of phenytoin or in patients of organic brain lesion, this side effect is very occasionally reported with even normal therapeutic drug level.

CLINICAL CASE

We report a case of young male presented with chorea after two months of starting phenytoin for primary generalised epilepsy with normal therapeutic serum drug level. After excluding other differentials, drug-induced chorea was the final diagnosis. Despite phenytoin level was in therapeutic range, we have a trial of stopping Phenytoin with complete disappearance of chorea in 3 days. On reintroduction of phenytoin in the same dose, there was the reappearance of chorea in onemonth re-emphasising the diagnosis as "phenytoin-induced chorea".

CONCLUSION

If any patient on phenytoin develops any new neurological feature including dyskinesias, it should be considered as an ADR despite drug serum level within the normal therapeutic range.

Choreoathetosis Is a Possible Adverse Event of a Commonly Used Antibiotic

BACKGROUND

Choreoathetosis (CAS) is attributed to a few neuropsychiatric drugs; however, it is scarcely reported with commonly used antibiotics.

AIMS

To present a case of ceftriaxone (CTX)-induced CAS and to perform a literature review.

SETTING

A medical teaching hospital.

CASE HISTORY

An 83-year-old female with end stage renal disease was prescribed CTX 2 g/day intravenously and doxycycline (DXC) 200 mg/day orally for the treatment of acute community-acquired systemic infection. CAS developed 3 days after the administration of both drugs. Withdrawal of CTX and DXC yielded complete resolution of the CAS on the following day. Neither neurological adverse events related to DXC use nor pharmacological interaction between DXC and CTX was reported. Therefore, the CAS development was attributed to CTX.

CONCLUSION

CTX as well as other ß-lactam antibiotics induce glutamate excess in the striatum and cerebral cortex, resulting in neurological hyperexcitability disorders. Dosage adjustment of these antibiotics in relation to the patients' renal clearance is warranted.

Nonprimary dystonias

Dystonias can be classified as primary or secondary, as dystonia-plus syndromes, and as heredodegenerative dystonias. Their prevalence is difficult to determine. In our experience 80-90% of all dystonias are primary. About 20-30% of those have a genetic background; 10-20% are secondary, with tardive dystonia and dystonia in cerebral palsy being the most common forms. If dystonia in spastic conditions is accepted as secondary dystonia, this is the most common form of all dystonia. In primary dystonias, the dystonic movements are the only symptoms. In secondary dystonias, dystonic movements result from exogenous processes directly or indirectly affecting brain parenchyma. They may be caused by focal and diffuse brain damage, drugs, chemical agents, physical interactions with the central nervous system, and indirect central nervous system effects. Dystonia-plus syndromes describe brain parenchyma processes producing predominantly dystonia together with other movement disorders. They include dopa-responsive dystonia and myoclonus-dystonia. Heredodegenerative dystonias are dystonic movements occurring in the context of other heredodegenerative disorders. They may be caused by impaired energy metabolism, impaired systemic metabolism, storage of noxious substances, oligonucleotid repeats and other processes. Pseudodystonias mimic dystonia and include psychogenic dystonia and various orthopedic, ophthalmologic, vestibular, and traumatic conditions. Unusual manifestations, unusual age of onset, suspect family history, suspect medical history, and additional signs may indicate nonprimary dystonia. If they are suspected, etiological clarification becomes necessary. Unfortunately, potential etiologies are legion. Diagnostic algorithms can be helpful. Treatment of nonprimary dystonias, with few exceptions, does not differ from treatment of primary dystonias. The most effective treatment for focal and segmental dystonias is local botulinum toxin injections. Deep brain stimulation of the globus pallidus internus is effective for generalized dystonia. Antidystonic drugs, including anticholinergics, tetrabenazine, clozapine, and gamma-aminobutyric acid receptor agonists, are less effective and often produce adverse effects. Dopamine is extremely effective in dopa-responsive dystonia. The Bertrand procedure can be effective in cervical dystonia. Other peripheral surgery, including myotomy, myectomy, neurotomy, rhizotomy, ramizectomy, and accessory nerve neurolysis, has largely been abandoned. Central surgery other than deep brain stimulation is obsolete. Adjuvant therapies, including orthoses, physiotherapy, ergotherapy, behavioral therapy, social support, and support groups, may be helpful. Analgesics should also be considered where appropriate.

Hyperkinetic movement disorders caused by corpus striatum infarcts: brain MRI/CT findings in three cases

Three patients with hemichorea/hemiballismus/hemidystonia caused by discrete contralateral infarction of the corpus striatum are presented. The infarcts were all small on CT or MRI brain scan and were lacunar in type. Small discrete infarction of basal ganglionic structures allows such adventitious movements to be manifested. Involvement of contiguous areas, seen with larger infarcts, can suppress such movements. The infrequency of such hyperkinetic movement disorders, and the subtle infarct appearance on brain scan, can lead to a delay in the diagnosis.

Dyskinesia induced by phenytoin

Phenytoin is an effective antiepileptic drug, although, it can be associated with many side effects, including dyskinesia.

OBJECTIVE

To describe the clinical characteristics of phenytoin induced dyskinesia.

METHODS

We investigated the occurrence of involuntary movements in patients followed at our adult and pediatric epilepsy clinics during the period of one year.

RESULTS

Three patients presented with phenytoin-induced dyskinesia: one adult with axial and orofacial dyskinesia, and two children with choreoathetosis. They did not have other signs of phenytoin intoxication and had complete recovery after phenytoin withdrawal.

CONCLUSION

Phenytoin induced dyskinesia may occur during either chronic or initial treatment and with normal serum phenytoin levels. However, it occurs most often in patients on polytherapy, usually after increasing dosage and with toxic serum levels. Other signs of phenytoin intoxication may be present in these patients, but often the dyskinesia is the only side effect, which may delay the diagnosis and treatment. The clinical characteristics of the involuntary movements vary and may be focal or generalized, most often characterized by choreoathetosis and dyskinesias. These may last for hours, days or even years, but frequently disappear completely after phenytoin withdrawal.

Neuronal loss from the subthalamic nuclei in a patient with progressive chorea

We present a case of an 80-year-old man who developed a seizure disorder at age 66 and was treated with chronic phenytoin. In the last 3 years of his life, he developed multiple neurological deficits, including bilateral chorea, ataxic gait, sensory neuropathy, and progressive dementia. After death from pneumonia, autopsy examination of the patient's brain was most remarkable for a selective loss of neurons from both subthalamic nuclei and Purkinje cell loss in the cerebellum. This pattern of injury is consistent with a toxic process and does not fit previously characterized pathological syndromes known to be associated with movement disorders or dementia or both. Phenytoin has been shown to cause choreiform movements, peripheral neuropathy, and cognitive decline in some patients, but the pathological basis for these changes has not been elucidated. The patient's chorea was very likely the result of neuronal loss in the subthalamic nuclei, but causes for his dementia and neuropathy were not found. The pathological findings may represent either an unusual form of chronic phenytoin toxicity or a previously undescribed primary degenerative brain syndrome.

Choreoathetosis as an initial sign of relapsing of herpes simplex encephalitis

Twelve children with type 1 herpes simplex encephalitis (3 with relapse, 9 without) have been monitored during the past 7 years. Ten of the children received intravenous infusion of acyclovir (30 mg/kg/day) for 10 days, 1 child who experienced relapse received 15 mg/kg/day, and another relapsed child received no antiviral agents until relapse. Relapse occurred 20-36 days after initial onset. All relapsed patients underwent another 10 days of acyclovir treatment (30 mg/kg/day). Choreoathetosis appeared as the initial sign of relapse followed by rapidly progressive unresponsiveness in all 3 relapsed patients: in 1 nonrelapsed patient choreoathetosis occurred during the recovery period. In these 4 patients involuntary movement was remitted within 3 months to 2 years. One patient with choreoathetosis died of measles pneumonia 4 months after onset of herpes simplex encephalitis and the surviving 3 were severely retarded. Although neuroimaging sparing of basal ganglia does not indicate structural and functional abnormalities, the disturbance of the neural connection among the basal ganglia and the cerebral cortex, which manifested severe damage over frontal, temporal, and parietal mantles on CT, may be the source of movement disorders in these patients. We conclude that choreoathetosis may be the first sign of relapse of herpes simplex encephalitis in children and may be an indicator of poor prognosis. The neuropathogenesis of choreoathetosis requires further investigation.

Phenytoin and dyskinesias: a report of two cases and review of the literature

Dyskinesia is a recognized but uncommon side-effect of treatment with phenytoin. Two additional cases of dyskinesia during treatment with phenytoin are described; both had radiographically documented thalamic infarctions. The reported experience to date with movement disorders induced by phenytoin is reviewed and the clinical features summarized. The available experimental evidence addressing the mechanism underlying this side effect is discussed.

Tardive dyskinesia with inflated neurons of the cerebellar dentate nucleus. Case reports and morphometric study

Four autopsied cases of tardive dyskinesia manifesting oral hyperkinesia revealed markedly inflated neurons in the cerebellar dentate nucleus (DN), which had not been described previously. The inflation of the neurons was proved to be statistically significant (P less than 0.01) by morphometric study. The nuclei were usually situated in the central portion of the cytoplasm. This inflated change was different from both central chromatolysis and grumose degeneration of the DN, typically observed in progressive supranuclear palsy and dentatorubropallidolysian atrophy, and seemed to be easy to miss without careful observation, since neuronal loss and gliosis were very mild in the DN. Among a few autopsied cases of tardive dyskinesia reported previously, degeneration of the DN was described in only two. It is believed, however, that the inflated neurons of the DN may not be so rare and may be related to the occurrence of some involuntary hyperkinesia, especially oral hyperkinesia following some neurotoxic disorders and/or neuroleptic medications.

Movement disorders in bacterial meningitis

Movement disorders developed in five children, ages 6 to 21 months, during the course of bacterial meningitis caused by Hemophilus influenzae (one), Streptococcus pneumoniae (one), Neisseria meningitidis (one), or Mycobacterium tuberculosis (two). Athetosis, choreoathetosis, and hemiballismus occurred, ranging in duration from hours to months. Cranial computed tomography, performed in four cases, showed no lesion of the basal ganglia. The movements were of such abrupt onset and severity that in four cases they were initially misinterpreted as seizures, and anticonvulsant therapy was contemplated. It is important to recognize the potential development of movement disorders during the acute phase of bacterial meningitis to preclude the inappropriate administration of anticonvulsant medication.

Phenytoin-induced orofacial dyskinesia. A case report

A 56-year-old man with a small glioblastoma multiforme in the right parasagittal region developed orofacial dyskinesia and slight writhing movement of his hands during treatment with phenytoin and phenobarbitone. The serum concentration of phenytoin was within the therapeutic range. The involuntary movements subsided following the withdrawal of the drugs. Phenytoin-induced involuntary movements have not been described previously in a case with such a small parasaggital tumour treated with phenytoin at a serum concentration of therapeutic range.

Dopaminergic supersensitivity after long-term administration of phenytoin in rats

Male albino rats (n = 10) were injected with phenytoin (PHT) every day for 20 consecutive days and were tested on days 21 and 28 for their response to 1 mg/kg apomorphine, a dopamine-receptor agonist. Rats treated with PHT showed an increased responsiveness to apomorphine-induced stereotypy on day 28, which is evidence for dopaminergic supersensitivity after long-term treatment with the drug. In experiment 2, a supersensitivity response to apomorphine-induced stereotypy was noted on day 14 after 10 days of PHT administration. In experiment 3, after 17 days of PHT administration, rats were also supersensitive to the climbing response induced by apomorphine. These results may explain, in part, the clinical findings of orofacial dyskinesias produced by PHT in epileptic patients.

Effects of withdrawal from long-term diphenylhydantoin treatment on audiogenic and maximal electroshock-induced seizures in rats

Rats withdrawal from long-term diphenylhydantoin treatment (DPH) were tested for their sensibility to convulsant stimuli. Animals were more sensitive to convulsions elicited by maximal electroshock and sound, respectively, at 48 and 72 h after drug removal. These results suggest that long-term DPH treatment might develop a central nervous system supersensitivity state.

The effects of diphenylhydantoin on rat behavior

Animals were administered increasing doses of diphenylhydantoin (DPH) for 20 days. During withdrawal they were observed in an open field. The results suggest that chronic DPH administration leads to a central supersensitivity phenomenon. Possible interference of DPH with dopaminergic systems was discussed.

Clinical and experimental studies of phenytoin-induced hyperkinesias

Phenytoin administration occasionally leads to the induction of hyperkinetic movement disorders. The pathophysiologic basis of this phenomena is unknown, but thought to be a toxic effect of phenytoin. Study of two cases of this disorder and a review of the literature suggest that antecedant pathologic changes in the basal ganglia are prerequisites for the development of phenytoin-induced hyperkinesias. In an animal model of tardive dyskinesia, phenytoin was found to enhance neuroleptic-induced behavioral supersensitivity but have no effect in control animals. We conclude that phenytoin induced hyperkinesias reflect a specific effect of phenytoin on an abnormal neural substrate and suggest the presence of an otherwise silent pathological alteration of the corpus striatum. The diagnostic value of an episode of phenytoin-induced hyperkinesia is discussed.