Neuroleptic Malignant Syndrome Improved with Intramuscular Administration of the Anticholinergic Agent, Biperiden

Anticholinergic drugs, such as biperiden, benztropine, and diphenhydramine, were used for neuroleptic malignant syndrome (NMS) in the 1980s and 1990s. However, they have not been recommended for pharmacotherapy in NMS since 2000, as they may prevent a decrease in body temperature by suppressing sweating. However, whether anticholinergic drugs actually exacerbate NMS remains unclear. This study highlights the usefulness of anticholinergic drugs, which are no longer attracting attention as current pharmacological treatments for NMS. I treated four NMS patients using anticholinergic drugs. Two patients were treated with biperiden alone, and the other two patients were treated with a combination of biperiden and other drugs, including dantrolene, amantadine, or diazepam. Intramuscular injection of biperiden improved muscle rigidity, tremors, dysphagia, and akinetic mutism. Psychiatrists are familiar with anticholinergic drugs as they are used for antipsychotic-induced akathisia and Parkinsonism. My study suggests that anticholinergic drugs, especially injectable formulations, can be a therapeutic option for NMS.

Serotonin syndrome overlapping with neuroleptic malignant syndrome: A case report and approaches for differentially diagnosing the two syndromes

Serotonin syndrome (SS) and neuroleptic malignant syndrome (NMS) are life-threatening adverse reactions caused by serotonergic antidepressants and neuroleptics, respectively. SS and NMS have overlapping clinical features, and thus differentially diagnosing the syndromes can be difficult in patients who are taking both types of drugs. Here, the author reports a unique case of a patient who developed SS that overlapped with NMS after taking imipramine and lithium carbonate with the subsequent addition of metoclopramide. This is the first case report of SS that overlapped with NMS. The author also briefly summarizes the clinical symptoms of each syndrome and describes the approaches that were used to differentially diagnose the two syndromes.

A rare case of neuroleptic malignant syndrome without elevated serum creatine kinase

Neuroleptic malignant syndrome (NMS) is a life-threatening adverse reaction to antipsychotic drugs. Although there is no specific examination able to diagnose NMS, serum creatine kinase (CK) elevation has been reported in over 90% of NMS patients. In this report, we describe a patient who developed NMS but had normal CK levels. The patient presented with hyperthermia of over 38°C, severe muscle rigidity, autonomic dysfunction, and altered mental status. Although serum CK levels were measured three times during the course of NMS, the levels were within the normal range. The patient died of respiratory failure 13 days after the onset of NMS symptoms. As patients without elevated serum CK levels are rarely reported, we discuss potential reasons why the serum CK was not elevated in our patient. This case shows clinicians that although serum CK elevation is a useful indicator for the early detection of NMS, the diagnosis of NMS must be determined by clinical symptoms as otherwise, the appropriate treatment procedures for NMS may be delayed.

Second case report of successful electroconvulsive therapy for a patient with schizophrenia and severe hemophilia A

Electroconvulsive therapy (ECT) is used for medication-resistant and life-threatening mental disorders, and therefore it occupies an important position in psychiatric treatment. ECT reportedly increases intracranial pressure and is suspected of increasing the risk of intracranial hemorrhage, especially in patients with hemorrhagic diseases such as hemophilia. A decrease in or loss of blood coagulation factors, including factor VIII and factor IX, are found in hemophilia A and B, respectively. Psychiatrists may hesitate to perform ECT on patients with bleeding tendencies, such as in hemophilia. Here, we report the successful use of ECT on a neuroleptic-resistant patient with schizophrenia and severe hemophilia A. We performed ECT 16 times supplemented with coagulation factor VIII to prevent intracranial and systematic hemorrhage. We administered factor VIII concentrates to the patient to keep factor VIII activity at 30%-40% during ECT. The patient did not show bleeding or other complications during the ECT sessions. We suggest that pretreatment with factor VIII can help manage the increased risks of intracranial and systematic bleeding during ECT that is present in patients with hemophilia A. The present report supports the idea of performing ECT safely on patients with hemophilia A by administering factor VIII.

Two cases of mild serotonin toxicity via 5-hydroxytryptamine 1A receptor stimulation

We propose the possibility of 5-hydroxytryptamine (5-HT)1A receptor involvement in mild serotonin toxicity. A 64-year-old woman who experienced hallucinations was treated with perospirone (8 mg/day). She also complained of depressed mood and was prescribed paroxetine (10 mg/day). She exhibited finger tremors, sweating, coarse shivering, hyperactive knee jerks, vomiting, diarrhea, tachycardia, and psychomotor agitation. After the discontinuation of paroxetine and perospirone, the symptoms disappeared. Another 81-year-old woman, who experienced delusions, was treated with perospirone (8 mg/day). Depressive symptoms appeared and paroxetine (10 mg/day) was added. She exhibited tachycardia, finger tremors, anxiety, agitation, and hyperactive knee jerks. The symptoms disappeared after the cessation of paroxetine and perospirone. Recently, the effectiveness of coadministrating 5-HT1A agonistic psychotropics with selective serotonin reuptake inhibitors (SSRIs) has been reported, and SSRIs with 5-HT1A agonistic activity have been newly approved in the treatment of depression. Perospirone is a serotonin-dopamine antagonist and agonistic on the 5-HT1A receptors. Animal studies have indicated that mild serotonin excess induces low body temperature through 5-HT1A, whereas severe serotonin excess induces high body temperature through 5-HT2A activation. Therefore, it could be hypothesized that mild serotonin excess induces side effects through 5-HT1A, and severe serotonin excess induces lethal side effects with hyperthermia through 5-HT2A. Serotonin toxicity via a low dose of paroxetine that is coadministered with perospirone, which acts agonistically on the 5-HT1A receptor and antagonistically on the 5-HT2A receptor, clearly indicated 5-HT1A receptor involvement in mild serotonin toxicity. Careful measures should be adopted to avoid serotonin toxicity following the combined use of SSRIs and 5-HT1A agonists.

Temporal changes in serum creatine kinase concentration and degree of muscle rigidity in 24 patients with neuroleptic malignant syndrome

Neuroleptic malignant syndrome (NMS) is a dangerous adverse response to antipsychotic drugs. It is characterized by the four major clinical symptoms of hyperthermia, severe muscle rigidity, autonomic dysfunction, and altered mental state. Serum creatine kinase (CK) elevation occurs in over 90% of NMS cases. In the present study, the detailed temporal changes in serum CK and degree of muscle rigidity, and the relationship between CK concentration and degree of muscle rigidity over the time course from fever onset, were evaluated in 24 affected patients. The results showed that serum CK peaked on day 2 after onset of fever and returned to within normal limits at day 12. Mild muscle rigidity was observed before the onset of fever in 17 of 24 cases (71%). Muscle rigidity was gradually exacerbated and worsened until day 4 after onset of fever. These findings confirm physicians' empirical understanding of serum CK concentrations and muscle rigidity in NMS based on data accumulated from numerous patients with the syndrome, and they indicate that serum CK may contribute to the early detection of NMS.

Increased biogenic catecholamine and metabolite levels in two patients with malignant catatonia

The pathophysiology of malignant catatonia, a rare life-threatening psychiatric syndrome, has not yet been elucidated. This paper reports on two patients with malignant catatonia who showed elevated urinary or plasma catecholamine levels. Patient 1 had high catecholamine and metabolite levels in a 24-hour urine sample, and patient 2 had elevated plasma catecholamine levels. These findings indicate the presence of peripheral sympathetic nervous system hyperactivity in malignant catatonia. Symptoms of autonomic dysfunction, including tachycardia, labile blood pressure, and diaphoresis, are typical features of malignant catatonia and may be related to the increased levels of biogenic amines in these cases. Although the findings in the present study cannot entirely explain the pathophysiology of malignant catatonia, they do indicate that hyperactivity of the sympathetic nervous system may be involved in the pathology of this condition.

Memantine attenuates 3,4-methylenedioxymethamphetamine-induced hyperthermia in rats

3,4-Methylenedioxymethamphetamine (MDMA) is an illegal drug that can induce life-threatening hyperthermia. No effective pharmacological treatment for MDMA-induced hyperthermia has yet been established. We investigated the effects of memantine, a non-competitive N-methyl-D-aspartate (NMDA)-type glutamate receptor antagonist and an α-7 nicotinic acetylcholine receptor (nAChR) antagonist, on MDMA-induced hyperthermia in rats. Treatment of animals with memantine (10 or 20 mg/kg) either before or after MDMA (10 mg/kg) administration significantly decreased the peak body temperature. Results from our microdialysis study indicated that pretreatment with memantine (20 mg/kg) before MDMA administration had no effect on the MDMA-induced increase in serotonin (5-HT) and dopamine (DA) levels in the anterior hypothalamus. MDMA-induced hyperthermia was significantly suppressed by pretreatment with the non-competitive NMDA receptor antagonist MK-801 (0.5 mg/kg) and the competitive NMDA antagonist CGS 19755 (5 mg/kg), but not by the selective α-7 nAChR antagonist methyllycaconitine (6 or 10 mg/kg). These results indicate that the inhibitory effect of memantine on MDMA-induced hyperthermia may be due to its activity as an NMDA receptor antagonist and not as a result of a direct effect on the 5-HT or DA systems. The present study suggests that moderate doses of memantine may be useful for the treatment of MDMA-induced hyperthermia in humans.

Risperidone attenuates the increase of extracellular nitric oxide and glutamate levels in serotonin syndrome animal models

Serotonin (5-hydroxytryptamine; 5-HT) syndrome is a potentially life-threatening neurotoxic condition provoked by pharmacologically induced excess serotonergic activity. Several studies report that nitric oxide (NO) and glutamate play a role in psychostimulant-induced hyperthermia related to neurotoxicity. In the present study, the involvement of NO and glutamate, as well as the effect of risperidone, a potent 5-HT(2A) and D(2) (and a less potent D(1)) receptor antagonist, were investigated in animal models of 5-HT syndrome. Two 5-HT syndrome animal models were utilized. The first model was induced by administration of tranylcypromine, a nonselective monoamine oxidase (MAO) inhibitor, and fluoxetine, a selective 5-HT reuptake inhibitor. The second model was induced by the administration of clorgyline, an MAO-A inhibitor, and 5-hydroxy-l-tryptophan, a precursor of 5-HT. Changes in the level of NO metabolites and glutamate in the anterior hypothalamus were measured using microdialysis. In both models, NO metabolite levels significantly increased, and this increase was significantly attenuated by risperidone pretreatment. Extracellular levels of glutamate were increased only in the tranylcypromine and fluoxetine model, and this increase was significantly attenuated by risperidone pretreatment. These results indicate that NO and glutamate may be involved in the development of 5-HT syndrome and that risperidone may be effective against neurotransmitter abnormalities in 5-HT syndrome.

Elevated creatine kinase does not necessarily correspond temporally with onset of muscle rigidity in neuroleptic malignant syndrome: a report of two cases

Neuroleptic malignant syndrome is an uncommon but dangerous complication of antipsychotic drugs, characterized by clinical symptoms that include hyperthermia, severe muscle rigidity, autonomic dysfunction, and altered mental state. Serum creatine kinase (CK) elevation occurs in over 90% of cases. Many diagnostic criteria sets for neuroleptic malignant syndrome have been proposed, all of which include hyperthermia and muscle rigidity as major symptoms, and serum CK elevation as either a major or minor symptom. In general, elevated CK occurs in the initial stage of neuroleptic malignant syndrome and corresponds temporally with the onset of muscle rigidity. However, in some exceptional cases, CK elevation and emergence of muscle rigidity do not appear in the same stage, making early diagnosis of neuroleptic malignant syndrome more difficult. Two rare cases of neuroleptic malignant syndrome are presented in which elevated serum CK and emergence of muscle rigidity did not occur in the same stage of neuroleptic malignant syndrome. An elevated CK level is common in the early stage of neuroleptic malignant syndrome, suggesting that serum CK elevation is a useful indicator for early detection of neuroleptic malignant syndrome. However, a definitive diagnosis of neuroleptic malignant syndrome must be determined from the presence of specific clinical symptoms.

Effect of risperidone on acute methamphetamine-induced hyperthermia in rats

The abuse of methamphetamine (METH) is popular in many parts of the world. The number of fatal cases related to METH-induced hyperthermia is increasing, but no definitive therapy has yet been found. In the present study, we investigated the ability of risperidone to attenuate acute METH-induced hyperthermia and the mechanism of its action. When administered before and after a single high METH dose (10 mg/kg), risperidone significantly suppressed acute METH-induced hyperthermia in a dose-dependent manner. The same effect was produced by dopamine-1 (DA(1)) and serotonin-2A (5-HT(2A)) receptor blockers, but not by D₂, 5-HT(1A), 5-HT(2B/2C), or 5-HT(2C) receptor blockers, demonstrating that risperidone suppressed METH-induced hyperthermia by blocking the D(1) and 5-HT(2A) receptors. A microdialysis study showed that when METH (10 mg/kg) was subcutaneously injected into rats, the levels of DA, 5-HT, glutamate, and the nitric oxide (NO) metabolites NOx (NO₂⁻+ NO₃⁻) in the anterior hypothalamus increased. Risperidone pretreatment significantly attenuated increases in the levels of DA, 5-HT, glutamate, and NOx. The present study indicates that risperidone may be an effective drug for treating METH-induced hyperthermia in humans and that METH influences the DA and 5-HT neuron systems as well as other neuron systems, including the glutamate and NO systems.

Oseltamivir (Tamiflu) increases dopamine levels in the rat medial prefrontal cortex

Oseltamivir (Tamiflu), a neuraminidase inhibitor, is effective for treating both seasonal flu and H5N1 influenza A virus infection. Oseltamivir is generally well tolerated, and its most common adverse effects are nausea and vomiting. However, neuropsychiatric behaviors including jumping and falling from balconies by young patients being treated by oseltamivir have been reported from Japan; this has led to warnings against its prescribing by many authorities. The pharmacological mechanism of the neuropsychiatric effects of oseltamivir remains unclear. Many studies reported that changes in neurotransmission and abnormal behaviors are closely related. We investigated the changes in dopamine and serotonin metabolism after systemic administration of oseltamivir in the medial prefrontal cortex (mPFC) of rats by using microdialysis. After systemic administration of oseltamivir (25mg/kg or 100mg/kg; intraperitoneally (i.p.)), extracellular dopamine in the mPFC was significantly increased as compared to the control values; 3,4-dihydroxyphenylacetic acid and homovanillic acid, the metabolites of dopamine, had also increased significantly. Serotonin was unchanged after the administration of oseltamivir. These findings suggest that oseltamivir increased dopamine release in the mPFC; further, they suggest that the increase in dopamine during oseltamivir treatment may have caused abnormal behaviors in young patients. In cases where oseltamivir is prescribed to children, close observation is required.

Neuroleptic malignant syndrome and serotonin syndrome

This chapter is focused on drug-induced hyperthermia with special regard to use of antipsychotics and antidepressants for the treatment of schizophrenia and major depression, respectively. Neuroleptic malignant syndrome (NMS) develops during the use of neuroleptics, whereas serotonin syndrome is caused mainly by serotoninergic antidepressants. Although both syndromes show various symptoms, hyperthermia is the main clinical manifestation. In this review we describe the historical background, clinical manifestations, diagnosis, and differential diagnosis of these two syndromes based on our observations on the experimental and clinical data.

Cerebral activation focusing on strong tasting food: a functional magnetic resonance imaging study

Very little research has been conducted on taste imagery because of the difficulty of doing so. We conducted a functional magnetic resonance imaging study to observe cerebral activation patterns produced in volunteers concentrating on pickled plums (umeboshi), a traditional Japanese food with a strong and sour taste. Activation was observed in the right insula, the bilateral opercula, the bilateral orbitofrontal cortices and the left Broca's area. Activation in the insula (primary gustatory area) was very weak and limited to one side. The activation pattern was similar to that of taste perception. Our results showed that it is possible for humans to imagine tastes.

Perospirone, a novel atypical antipsychotic drug, potentiates fluoxetine-induced increases in dopamine levels via multireceptor actions in the rat medial prefrontal cortex

Perospirone is a novel atypical antipsychotic with a unique combination of 5-HT1A receptor agonism as well as 5-HT2A and D2 receptor antagonism. We investigated the effect of perospirone in combination with fluoxetine on dopamine release in the rat medial prefrontal cortex using microdialysis. Perospirone and fluoxetine increased dopamine release to 270 and 210% of the baseline value, respectively. A combination of perospirone and fluoxetine markedly increased dopamine release to 800% of the baseline value. Pretreatment with a selective 5-HT1A receptor antagonist, WAY 100635, suppressed the increase in dopamine levels induced by the administration of perospirone and fluoxetine to 330% of the baseline value. These findings suggest that perospirone potentiates fluoxetine-induced dopamine increases in part via the action of the 5-HT1A receptor and may augment the effect of fluoxetine in treatment-resistant depression.

Extracellular serotonin, dopamine and glutamate levels are elevated in the hypothalamus in a serotonin syndrome animal model induced by tranylcypromine and fluoxetine

Serotonin (5-HT) syndrome is a potentially fatal condition associated with various combinations of serotonergic drugs. The present study was undertaken to demonstrate that nervous systems other than the 5-HT system also participate in the pathophysiology of 5-HT syndrome. Concentrations of 5-HT, dopamine (DA) and glutamate in the hypothalamus were measured in two different 5-HT syndrome animal models using a microdialysis technique. The first model was induced by tranylcypromine, a nonselective monoamine oxidase (MAO) inhibitor (3.5 mg/kg) and fluoxetine, a selective serotonin reuptake inhibitor (SSRI) (10 mg/kg). The second model was induced by clorgyline, an MAO-A inhibitor (1.2 mg/kg) and 5-hydroxy-L-tryptophan, a precursor of 5-HT (5-HTP) (80 mg/kg). In the first model, the levels of 5-HT and DA increased by 40-fold and 44-fold, respectively, compared with the preadministration levels. In the second model, the concentrations of 5-HT increased by up to 140-fold, whereas DA levels increased by only 10-fold, of the preadministration levels. Although the level of glutamate in the second model barely changed, a delayed increase in the glutamate level was observed in the first model. These findings suggest that not only hyperactivity of the 5-HT system, but also hyperactivity of the DA system, are present in 5-HT syndrome, and that the glutamatergic system is influenced in some 5-HT syndrome cases in which the DA concentration markedly increases.

Memantine, an NMDA Antagonist, Prevents the Development of Hyperthermia in an Animal Model for Serotonin Syndrome

BACKGROUND

Serotonin (5-HT) syndrome is the most serious side effect of antidepressants. Although several drugs have been used for the treatment of 5-HT syndrome, a universal pharmacotherapy has not been established. NMDA receptor antagonists have been reported to have neuroprotective effects. In the present study, the efficacy of NMDA antagonists, including memantine and MK-801, and potent 5-HT (2A) antagonists, including risperidone and ketanserin, was evaluated in a 5-HT syndrome animal model.

METHODS

5-Hydroxy-l-tryptophan (100 mg/kg) and clorgyline (2 mg/kg) were administered intraperitoneally in rats to induce 5-HT syndrome. The rectal temperature of the rats was measured, and the noradrenaline (NA) and 5-HT levels in the anterior hypothalamus were measured using a microdialysis technique.

RESULTS

In the group pretreated with saline, the rectal temperature increased to more than 40 degrees C, and all of the animals died within 90 min of the drug's administration. The NA and 5-HT levels in the anterior hypothalamus increased to about 15- and 1100-fold of the pre-administration levels, respectively. Pretreatment with risperidone (0.5 mg/kg) and ketanserin (5 mg/kg) prevented the development of hyperthermia and the increase in the NA level. Memantine (10 mg/kg) and MK-801 (0.5 mg/kg) also prevented the development of hyperthermia and the increase in the NA level. These results suggest that NMDA antagonists, as well as potent 5-HT (2A) antagonists, may be effective drugs for the treatment of 5-HT syndrome.

CONCLUSIONS

Since memantine is clinically well tolerated, this drug is a particularly promising therapeutic drug for 5-HT syndrome treatment.

Diazepam and chlormethiazole attenuate the development of hyperthermia in an animal model of the serotonin syndrome

The serotonin (5-HT) syndrome is the most serious toxic interaction of antidepressants, but no pharmacotherapy has yet been established. In the present study, we created an animal model of the 5-HT syndrome by intraperitoneally injecting rats with clorgyline (2 mg/kg) and 5-hydroxy-L-tryptophan (5-HTP) (100 mg/kg) and evaluated the effectiveness of potent 5-HT(2A) receptor antagonists and GABA-enhancing drugs, including diazepam and chlormethiazole. The rectal temperature of the rats was measured, and the noradrenaline (NA) and 5-HT levels in the anterior hypothalamus were measured by microdialysis. In the group pre-treated with saline, the rectal temperature increased to more than 40 degrees C, and all of the animals died within 90 min after administration. Pre-treatment with potent 5-HT(2A) receptor antagonists prevented the development of hyperthermia and death in the rats. Pre-treatment with diazepam, 10 and 20mg/kg, and chlormethiazole, 50 and 100mg/kg, attenuated the development of hyperthermia. Although neither of these drugs completely prevented the rats from dying, they prolonged their survival time. Regardless of the type of therapeutic agents, the concentration of 5-HT increased to about 1100-fold the pre-administration level. The NA levels in the saline group increased to about 16-fold the pre-administration levels, but the increase was significantly lower in the rats that survived as a result of drug therapy. These results suggest that GABA-mimetic drugs may be effective against the 5-HT syndrome, although they have a somewhat weaker effect than the potent 5-HT(2A) receptor blockers, and that not only is 5-HT activity increased in the brain in the 5-HT syndrome, but the NA system is also enhanced.

Tandospirone potentiates the fluoxetine-induced increases in extracellular dopamine via 5-HT(1A) receptors in the rat medial frontal cortex

Recent clinical studies suggest that 5-HT(1A) receptor agonists, including buspirone, may have an antidepressant effect and potentiate the efficacy of selective serotonin reuptake inhibitors (SSRI) in major depressive disorders. In the present study, we investigated the effect of tandospirone, a highly potent and selective 5-HT(1A) receptor agonist, on dopamine release and potentiation of fluoxetine-induced dopamine outflow in the medial frontal cortex using microdialysis in freely moving rats. Intraperitoneal injection of tandospirone (5 mg/kg) increased dopamine release to about 190% of basal levels. Pretreatment with the selective 5-HT(1A) receptor antagonist, WAY 100635 (1mg/kg), blocked the effect of tandospirone. Local application of WAY 100635 (10 microM) via microdialysis probe antagonized the increase in dopamine release in the medial frontal cortex induced by systemic injection of tandospirone. Fluoxetine (10 mg/kg) also increased dopamine release in the medial frontal cortex, to 200% of basal levels, and the simultaneous administration of tandospirone and fluoxetine increased the release to 380%. These results indicate that tandospirone potentiates the fluoxetine-induced increase in dopamine release via 5-HT(1A) receptors in the rat medial frontal cortex, and suggest that tandospirone may have therapeutic potential for the treatment of depression.

Pitch perception shift: a rare side-effect of carbamazepine

Carbamazepine-induced pitch perception shifts have rarely been described. Two cases of shifted pitch perception developing during medication with carbamazepine are described. Case 1 possessed absolute pitch. Her pitch perception shift disappeared with the discontinuance of carbamazepine. Case 2 did not have absolute pitch. Even though he experienced a pitch perception shift, he developed a tolerance to the shift. We concluded that carbamazepine was the cause of the pitch perception shift in the first case, while the second case probably became attuned to the change in pitch perception because he did not possess absolute pitch.

Potent serotonin (5-HT)(2A) receptor antagonists completely prevent the development of hyperthermia in an animal model of the 5-HT syndrome

The serotonin (5-HT) syndrome is the most serious side effect of antidepressants, and it often necessitates pharmacotherapy. In the present study, the efficacy of several drugs was evaluated in an animal model of the 5-HT syndrome. When 2 mg/kg of clorgyline, a type-A monoamine oxidase inhibiting antidepressant, and 100 mg/kg of 5-hydroxy-L-tryptophan, a precursor of 5-HT, were administered intraperitoneally to rats to induce the 5-HT syndrome, the rectal temperature of the rats increased to more than 40 degrees C, and all of the animals died by 90 min after the drug administration. The noradrenaline (NA) levels in the anterior hypothalamus, measured by microdialysis, increased to 15.9 times the preadministration level. Pretreatment with propranolol (10 mg/kg), a 5-HT(1A) receptor antagonist as well as a beta-blocker, and dantrolene (20 mg/kg), a peripheral muscle relaxant, did not prevent the death of the animals, even though these two drugs suppressed the increase in rectal temperature to some extent. Chlorpromazine and cyproheptadine prevented the lethality associated with the 5-HT syndrome only at high doses. By contrast, pretreatment with ritanserin (3 mg/kg) and pipamperone (20 mg/kg), both potent 5-HT(2A) receptor antagonists, completely prevented the increase in rectal temperature and death of the animals, and the hypothalamic NA levels in these two groups increased less than that in the other groups. These results suggest that potent 5-HT(2A) receptor antagonists are the most effective drugs for treatment of the 5-HT syndrome, and that NA hyperactivity occurs in the 5-HT syndrome.

Risperidone counteracts lethality in an animal model of the serotonin syndrome

RATIONALE

The serotonin (5-HT) syndrome is the most serious side effect of antidepressants, and pharmacologic treatment should be offered in severe cases.

OBJECTIVE

In the present study, the effects of risperidone, ketanserin, and haloperidol on an animal model of the serotonin (5-HT) syndrome were evaluated.

METHODS

Intraperitoneal administration of 100 mg/kg 5-hydroxy-L-tryptophan (5-HTP) (a precursor of 5-HT) and 2 mg/kg clorgyline (a monoamine oxidase type-A inhibiting antidepressant) induced the 5-HT syndrome in rats. The rectal temperature of the rats was measured, and the microdialysis method was used to measure noradrenaline (NA) levels in the anterior hypothalamus.

RESULTS

In the group pre-treated with saline, the NA concentration increased to 13 times the pre-administration level, rectal temperature increased to more than 40 degrees C, and all of the animals died 75 min later. In the group pre-treated with risperidone (0.5 mg/kg), the 5-HT syndrome was completely inhibited, and the NA level increased to 6.5 times the pre-administration level. Ketanserin, a selective 5-HT2A antagonist (5 mg/kg) also inhibited the 5-HT syndrome. In contrast, all of the rats in the group pre-treated with haloperidol (0.5 mg/kg) died earlier than in the saline group.

CONCLUSIONS

These results suggest that strong 5-HT2A antagonists such as risperidone, but not dopamine D2 antagonists, counteract lethality due to 5-HT syndrome, and that not only does enhancement of 5-HT activity occur in the 5-HT syndrome, but NA activity also increases.

Electroconvulsive therapy for the treatment of neuroleptic malignant syndrome with psychotic symptoms: a report of five cases

We report five cases of neuroleptic malignant syndrome (NMS) with psychotic symptoms treated with electroconvulsive therapy (ECT). Clinical response was observed after the first or the second session of ECT in every case, and the symptoms of NMS resolved by the third or fourth session. The mean time from the initial ECT to complete resolution was 6.0 days. No side effects from ECT were observed. Although the first treatment for NMS is pharmacotherapy using drugs such as dantrolene and bromocriptine, our results suggest that ECT is a useful therapeutic method for patients with NMS and psychotic symptoms.

Addition of carbamazepine to long-term treatment with neuroleptics may induce neuroleptic malignant syndrome

BACKGROUND

Carbamazepine is an anticonvulsant, but also has an anti-manic effect, and recently it has been increasingly used in combination with neuroleptics. Nevertheless, there have been very few reports on the involvement of carbamazepine in the occurrence of neuroleptic malignant syndrome (NMS).

METHODS

A case of NMS occurring after addition of carbamazepine to long-term neuroleptic administration is described.

RESULTS

The patient had been treated with neuroleptics for about 30 years, and NMS developed when carbamazepine (400 mg/day) was added.

CONCLUSIONS

This case suggests that clinicians should consider the risk of NMS when carbamazepine is administered to patients undergoing long-term treatment with neuroleptics.

Treatment of tardive dystonia with an antispastic agent

Tardive dystonia is a difficult condition to treat. We describe the case of a patient with tardive dystonia that was unresponsive to various pharmacological and electroconvulsive therapies. The patient showed dramatic improvement after the administration of eperisone, a centrally acting muscle relaxant. Eperisone and tolperisone are beta-aminopropiophenone derivatives which are used clinically as antispastic agents. To date there have been no reports describing the effect of such muscle relaxants on tardive dystonia. The results of our study suggest that these muscle relaxants may be promising therapeutic drugs for the treatment of tardive dystonia.

A case of serotonin syndrome induced by concomitant treatment with low-dose trazodone and amitriptyline and lithium

We describe a patient treated with trazodone, amitriptyline and lithium carbonate who developed anxiety, restlessness, tremor, myoclonus, hyperreflexia, diaphoresis, rigidity and hyperthermia. The constellation of findings was diagnostic of serotonin syndrome. Although doses of trazodone and amitriptyline were relatively low, serotonin syndrome developed in this patient. It is suggested that the combination with lithium facilitated the effect of central serotonergic responses mediated by trazodone and amitriptyline.

Cerebrospinal fluid levels of monoamine metabolites and gamma-aminobutyric acid in neuroleptic malignant syndrome

To investigate the pathophysiology of neuroleptic malignant syndrome (NMS), we measured various cerebrospinal fluid (CSF) parameters in 11 patients and compared them with 8 age-matched normal controls. Concentrations of homovanillic acid (HVA) were significantly decreased during the active phase of NMS. This finding indicates that the dopaminergic nervous system of the patients was in a state of hypofunction in this phase and supports the central dopamine blockade theory of NMS. Reduced CSF HVA levels were also found after recovery from NMS, suggesting that hypofunction of the dopaminergic system may continue subclinically. The levels of 5-HIAA were decreased in the active phase, but the change was not significant. Therefore, a relationship between the development of NMS and disturbances of serotonin metabolism remains unclear. The levels of noradrenaline and its major metabolite, 3-methoxy-4-hydroxyphenylethyleneglycol increased significantly during the active phase, but returned to normal after recovery. These results show the existence of sympathetic nervous system hyperactivity during the active phase of NMS. The levels of gamma-aminobutyric acid (GABA) were significantly lower in the patients than in the controls. These findings suggest that there is a GABAergic deficiency in NMS. Thus, our study indicates that, in addition to dopamine hypoactivity, disturbances in various neurotransmitter systems are involved in the pathophysiology of NMS.

Single photon emission computed tomography with 123I-IMP in three cases of the neuroleptic malignant syndrome

Single photon emission computed tomography (SPECT) perfusion brain scans using 123I-N-isopropyl-p-iodoamphetamine (123I-IMP) were performed in three patients with the neuroleptic malignant syndrome (NMS). In two accumulation was increased in the left basal ganglia and decreased in the right on the early images during the active phase of NMS; this asymmetry was not seen after recovery. In the third patient two examinations were performed during the active phase; on the first, increased accumulation of 123I-IMP in the left basal ganglia was found on the early images, but on the second, increased accumulation of tracer was found in the right basal ganglia on the delayed images. These abnormalities disappeared after improvement of the NMS. These results suggest that a disturbance in the basal ganglia is related to the development of NMS.

Does dantrolene influence central dopamine and serotonin metabolism in the neuroleptic malignant syndrome? A retrospective study

Homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) levels in the cerebrospinal fluid (CSF) were determined twice in nine cases of neuroleptic malignant syndrome (NMS) during the active phase. During the test period, three cases received no dantrolene and six cases received dantrolene prior to the second CSF examination. In the group not administered dantrolene, the levels of HVA and 5-HIAA were lower on the second examination compared to the first, suggesting that the levels of these substances decreased during the course of NMS. In the group receiving dantrolene, the levels of HVA and 5-HIAA increased after administration compared with the preadministration levels. In particular, a significant difference in the changes in HVA was demonstrated between the two groups. This suggests that dantrolene influences central dopaminergic metabolism in the active phase of NMS.

Neuroleptic malignant syndrome: a study of CSF monoamine metabolism

In 8 cases of typical neuroleptic malignant syndrome (NMS), homovanillic acid (HVA), 5-hydroxyindole acetic acid (5-HIAA), noradrenaline (NA), and 3-methoxy-4-hydroxyphenylethyleneglycol (MHPG) levels in the cerebrospinal fluid (CSF) were assayed during both the active phase of NMS and after recovery. Compared with levels in normal control subjects the levels of HVA were significantly lower in patients with active NMS. This finding supports the central dopamine blockade theory of NMS pathophysiology. In addition, the levels of HVA were significantly decreased after recovery, suggesting that there may be a decreased dopamine metabolism in patients susceptible to NMS. The levels of 5-HIAA in patients with active NMS and after recovery were also significantly lower than those in normal control group, suggesting a relationship between the development of NMS and a disturbance of serotonin metabolism. The levels of NA in patients with active NMS were significantly higher than in normal subjects, and were within normal range after recovery. The levels of MHPG had a tendency to increase in patients with active NMS, compared with levels during recovery. These findings are a result of increased sympathetic nervous system activity in patients with active NMS; however, they are also observed in other disorders and may well reflect the physical stress caused by NMS.