Cerebellar degeneration following neuroleptic malignant syndrome

The Syndrome of Irreversible Lithium-Effectuated Neurotoxicity: A Scoping Review

The Syndrome of Irreversible Lithium-Effectuated Neurotoxicity (SILENT) is a rare but concerning neurological complication resulting from lithium intoxication. Despite being reported since the 1960s, SILENT remains poorly understood and previous reviews on this topic commonly have been narrative. We therefore conducted a scoping review to assess the nature and scope of the research literature on the long-term neurological sequelae of lithium toxicity and determine the current knowledge of SILENT. A comprehensive and systematic literature search, using the MEDLINE, Embase, and Web of Science databases (from inception to July 2023), was conducted for English and Dutch articles, assessing the long-term neurological sequelae of lithium intoxication. Key information concerning clinical manifestations, risk factors, therapeutic approaches, or preventive measurements was extracted. We reviewed 91 articles, extracting information from 117 cases of SILENT. The prevailing outcome observed was persistent cerebellar dysfunction (77% of cases), often in combination with other sequelae. Other common sequelae included cognitive problems, parkinsonism, choreoathetosis, tardive dyskinesia, and peripheral neuropathy. The most common (61.4%) acute neurological symptom in the development of SILENT is an altered level of consciousness ranging from confusion to comatose states. Cerebellar sequelae were mentioned in 77% of cases as most common persistent sequelae. Antipsychotic use was mentioned in 59% of cases and fever was reported in 37.6% of cases. Scientific knowledge about this phenomenon has not advanced much since its initial reports in the 1960s and 1970s. While the use of lithium has become much more stringent than it had been in years past, and the occurrence of SILENT is rather exceptional, raising awareness about SILENT nevertheless remains crucial to avoid deleterious neurological consequences. Comprehensive, high-quality research in a systematic and standardized manner is therefore urgently needed to better understand this phenomenon.

A reappraisal of the role of fever in the occurrence of neurological sequelae following lithium intoxication: a systematic review

INTRODUCTION

We aimed to review cases of Syndrome of Irreversible Lithium-Effectuated Neurotoxicity (SILENT) characterized by neurological sequelae following acute lithium toxicity and to explore whether cerebellar sequelae are more frequent in cases presenting with fever and/or infection.

AREAS COVERED

Case reports were identified from: (i) 6 reviews published up to 2005; (ii) MEDLINE, Web of Sciences, Cochrane Library and PsycINFO search.

EXPERT OPINION

We identified 123 SILENT cases published from 1965 to 2019, in which cerebellar sequelae were observed in an overwhelming proportion (79%). SILENT may occur at any time during lithium treatment. This complication is most frequently observed during routine lithium treatment, with fewer than 10% of cases occurring after accidental or intentional overdoses. SILENT may occur even when lithium plasma levels are within the therapeutic range: 63% of cases had lithium plasma level <2.5 mEq/l (low/mild toxicity). Fever and/or infection were reported in nearly half of the patients (48%). The likelihood of presenting with cerebellar vs. other neurological sequelae was independently increased by elevated plasma lithium level (≥ 2.5 mEq/l) and by a history of fever and/or infection. Lithium users should be warned of the need to consult in case of fever to adjust their lithium dosage.

Radiology of post-operative paediatric cerebellar mutism syndrome

BACKGROUND

Post-operative paediatric cerebellar mutism syndrome is a well-recognized complication following posterior fossa tumour resection in children. Over the past few decades, imaging has played an important role in understanding this disorder.

AIM

This review article aims to focus on the disorder from a radiological perspective, summarizing the salient radiological evidence related to the anatomical structures, pathophysiology, and risk factors related to this disorder.

CONCLUSION

Radiological studies have been integral to the improved understanding of this condition. Future large multicentre studies and quantitative analysis techniques will be vital in further refinement of our understanding of this complex condition.

Use of Expert Consultation in a Complex Case of Neuroleptic Malignant Syndrome Requiring Electroconvulsive Therapy

Our team at Emory University Hospital contacted experts at the National Network of Depression Centers (NNDC) for clinical guidance concerning a patient with schizophrenia hospitalized in the intensive care unit with a complex case of prolonged delirium secondary to neuroleptic malignant syndrome (NMS). Through the NNDC, leading psychiatrists across the United States with expertise in electroconvulsive therapy (ECT) provided us with treatment strategies based on experience in our area of concern. This report describes our use of ECT to treat severe NMS in this patient with schizophrenia, utilizing the recommendations made by the NNDC's ECT experts concerning electrode position, number and frequency of treatments, and selection of anesthetic induction agents. This case report highlights the utility of expert consultation in the treatment of rare diseases and provides guidance on how to treat NMS in the intensive care unit setting.

The neurological and cognitive consequences of hyperthermia

An elevated temperature has many aetiologies, both infective and non-infective, and while the fever of sepsis probably confers benefit, there is increasing evidence that the central nervous system is particularly vulnerable to damage from hyperthermia. A single episode of hyperthermia may cause short-term neurological and cognitive dysfunction, which may be prolonged or become permanent. The cerebellum is particularly intolerant to the effects of heat. Hyperthermia in the presence of acute brain injury worsens outcome. The thermotoxicity involved occurs via cellular, local, and systemic mechanisms. This article reviews both the cognitive and neurological consequences and examines the mechanisms of cerebral damage caused by high temperature.

Posterior fossa syndrome following brain tumour resection: review of pathophysiology and a new hypothesis on its pathogenesis

INTRODUCTION

Posterior fossa syndrome (PFS), also known as cerebellar mutism syndrome (CMS), is a severe complication affecting children following surgery for posterior fossa brain tumours. Its incidence varies between 8 and 31 %, and its exact pathogenesis remains unclear. In this article, we aim to review the existing theories on its pathogenesis and propose a new hypothesis.

DISCUSSION

There is varying level of evidence on existing theories on the pathogenesis of PFS following surgery. These include cerebellar perfusion deficits due to vasospasm, oedema or axonal injury due to direct surgical injury and neuronal dysfunction. There is emerging evidence that interruption of the dentato-thalamo-cortical (DTC) pathway is responsible for PFS. Based on our experience with intraoperative MRI, radiological and pathological evidence on heat-related brain injury, we propose a new hypothesis implicating thermal injury resulting from the use of the Cavitron Ultrasonic Aspirator (CUSA) as an important mechanism in the pathogenesis of PFS.

CONCLUSION

The pathogenesis of PFS is likely to be multifactorial with direct injury from surgery being a major factor. We believe that thermal injury in addition to mechanical injury to the proximal segment of the DTC plays an important role in the pathogenesis of PFS and should be considered in future research related to the aetiology, prevention and management of PFS.

Selective cerebellar and basal ganglia injury in neuroleptic malignant syndrome

BACKGROUND AND PURPOSE

High core body temperatures have been shown to selectively damage the cerebellum and basal ganglia in malignant hyperthermia, but involvement of both areas in neuroleptic malignant syndrome (NMS) has not been described.

METHODS

Here, we report a case of acute cerebellar and basal ganglia injury by magnetic resonance imaging (MRI) in the setting of NMS. We discuss the pathophysiology, both of NMS and hyperthermic brain injury.

RESULTS

MRI showed new restricted diffusion in cerebellar hemispheres bilaterally and right basal ganglia when compared with brain MRI obtained 1 month prior. T2 FLAIR hyperintensities corresponding to diffusion restriction were also seen in the cerebellum.

CONCLUSIONS

Both the basal ganglia and cerebellum can be injured selectively in NMS.

Brain injury following neuroleptic malignant syndrome: case report and review of the literature

OBJECTIVE

To report a case of brain injury following neuroleptic malignant syndrome (NMS) and review the literature for similar documented cases.

CASE REPORT

A 30-year old woman presented to the ER with psychotic features and was treated with several anti-psychotics. Subsequently, she developed neurological symptoms and was diagnosed with neuroleptic malignant syndrome. Following a prolonged course in an acute care facility, she was admitted to a rehabilitation ward, where cognitive and physical examinations revealed significant findings. These included marked dysarthria, difficulties comprehending commands, attention problems, as well as abnormalities in her muscle tone, power, reflexes, gait, co-ordination and sensory function.

CONCLUSION

Literature reviews reveal few documented cases of brain injury following neuroleptic malignant syndrome. A further exploration of the effects of NMS on the brain is warranted to elicit whether cerebellar damage is indeed common following neuroleptic malignant syndrome. Such research could eventually lead to therapeutic interventions aimed at preventing permanent brain injury in persons with NMS.

Brain damage after heat stroke

Cerebellar syndromes and radiologic cerebellar atrophy after hyperpyrexia have occasionally been reported, mostly in neuroleptic malignant syndromes, but neuropathologic studies are extremely rare. We studied 3 patients (a 74-year-old woman, a 63-year-old man, and an 80-year-old man) who had heat stroke during heat waves in France. One patient had generalized seizures and died 28 hours after admission. The other patients survived one month and 2 months after admission; both had palatal myoclonus, and in one case, magnetic resonance imaging showed high signal intensity in the cerebral peduncles. The main neuropathology in the 3 cases was severe diffuse loss of Purkinje cells associated with heat shock protein 70 expression by Bergmann glia. In situ end labeling was negative in surviving Purkinje cells, suggesting that the mechanism of neuronal death was not apoptosis. Degeneration of Purkinje cells axons resulted in myelin pallor of the white matter of the folia and of the hilum of the dentate nuclei. DNA internucleosomal breakages were identified by in situ end labeling in the dentate nuclei and centromedian nuclei of the thalamus and were associated with degeneration of the cerebellar efferent pathways: superior cerebellar peduncles, decussation of the superior cerebellar peduncles (Wernekinck commissure), and dentatothalamic tract. These findings suggest that the mechanisms of neuronal death in the dentate nuclei and centromedian nuclei of the thalamus was different from that in Purkinje cells and more likely resulted from deafferentation. Ammon's horn and other areas susceptible to hypoxia were spared. These observations confirm the selective vulnerability of Purkinje cells to heat-induced injury and involvement of the cerebellar efferent pathways in palatal myoclonus.

Neuropsychiatric sequelae of neuroleptic malignant syndrome

The authors review the literature on persistent sequelae of neuroleptic malignant syndrome (NMS). They highlight the clinical presentations, assessment, and management of persistent sequelae and stress the need to take preventive steps to minimize their occurrence. The authors conducted a Medline and PubMed search for papers on residual sequelae of NMS. They cross-referenced the available papers and "operationalized" the diagnostic criteria for persistent neuropsychiatric sequelae. A total of 31 cases of neuropsychiatric sequelae of NMS were identified. With reduction in mortality from NMS, persistent sequelae of NMS have assumed clinical importance. Long-term sequelae persist for weeks to months after amelioration of an acute episode. Individuals with a preexisting CNS insult are more predisposed to develop persistent sequelae. A high index of awareness for persistent sequelae is warranted because antipsychotics are widely used for psychiatric disorders besides schizophrenia. Awareness of such outcomes and the use of evidence-based strategies to minimize risk factors will help clinicians in reducing the persistent sequelae of NMS.