31 Jan, 17 | by Dr Jose Manuel Matamala, JNNP web editor.
In the current issue of JNNP, Varges and colleagues have published a randomized control trial (RCT) phase II comparing doxycycline versus placebo in early sporadic Creutzfeldt-Jakob disease (sCJD).
CJD is a fatal and heterogeneous neurodegenerative disease caused by the misfolding and aggregation of prions. Clinically, CJD is characterized by rapidly progressive cognitive impairment associated with motor dysfunction (e.g. ataxia and tremor), with an average survival time of 4 – 6 months. Even though tremendous advances have been achieved in the comprehension of this disease, clinical trials including a previous trial of doxycycline have not yet been successful.
In this study, the authors report results of an RCT as well as an observational study assessing the use of doxycycline in early stages of sCJD. In the RCT, seven patients in the treatment group were compared with five patients on placebo, with no significant differences in survival. In the observational study, 55 patients with sCJD who received compassionate treatment with doxycycline were compared with historical control subjects. The treatment group showed a significantly longer survival, a difference that was driven by the differential effect of the codon 129 genotype status (methionine/methionine). Subsequently, combined data from both studies in a random-effects meta-analysis showed a slight increase in survival time for the doxycycline treatment group (HR = 0.63 (95% CI 0.401 to 0.999)).
Prion disease and doxycycline. Doxycycline was reported as an antiprion agent in different experimental models. In this study the combined data from a RCT and an observational study of early sCJD patients treated with doxycycline showed a slight increase in survival time in the doxycycline treatment group.
This recent JNNP article shows us the many barriers to conducting clinical trials in CJD patients, including the small sample size, genetic heterogeneity, problems with patient recruitment during the early stages of the disease, together with difficulties in follow-up given the rapid neurological deterioration. Despite the possible methodological bias of this article, there are two clear lessons to highlight: i) early treatment in sCDJ should increase the likelihood of better survival outcome and ii) doxycycline may have a differential therapeutic effect related with the specific molecular subtypes of sCJD. Regarding the early diagnosis of sCDJ patients, the combination of clinical and paraclinical tools, together with the use of novel biomarker such us ultrasensitive seeding assays based on the amplification and detection of prions (e.g. RT-QuIC), may optimize the early diagnoses and the design of future clinical trials. Finally, as also suggested by the authors, a larger RCT of doxycycline use in early sCDJ should be tested.
This is an interesting study, which provides valuable insights into the challenges and future direction of clinical trials in CJD patients.
Read more at http://jnnp.bmj.com/content/88/2/119.full.pdf
28 Nov, 16 | by Dr Jose Manuel Matamala, JNNP web editor.
In the current issue of JNNP, Kleffner and colleagues have published the first diagnostic criteria for diagnosing Susac syndrome based on clinical and paraclinical findings.
Susac syndrome is an uncommon disease characterized by the present of encephalopathy with or without focal neurological signs, branch retinal artery occlusion and neuro-sensorial hearing loss. Even though this clinical triad had been considered pathognomonic, only 13% of the patients presented at disease onset. The infrequent and clinically incomplete presentation of this syndrome usually leads to misdiagnosis, often diagnosed and treated as multiple sclerosis, therapy which may exacerbate Susac syndrome.
In this study, the interdisciplinary experts of the European Susac Consortium (EuSac) team have established a new diagnostic criteria for Susac syndrome based on a three steps process: (i) definition of a reference group of patients with Susac syndrome, (ii) selection of new diagnostic criteria based on the clinical and paraclinical findings (brain MRI, ophthalmological and vestibulocochlear tests) on the reference group and on the available literature cases and (iii) validation of the proposed criteria in a cohort of possible Susac syndrome (reported until 2012). After definition of the diagnostic criteria, more than 90% of Susac syndrome cases reported in the literature fulfilled the proposed criteria of probable or definitive, and 56% filled the criteria for definitive Susac syndrome. The authors conclude that these new criteria may help clinicians to make an earlier, accurate diagnosis of Susac syndrome, preventing the delay of treatment initiation.
The new diagnosis criteria for Susac syndrome. The new criteria are based on the presence of clinical and paraclinical evidence of involvement of the three main affected systems: (i) brain involvement (clinical findings + imaging), (ii) retinal involvement based on ophthalmological examination, and (iii) vestibulocochlear involvement (clinical findings + examination of inner ear function).
The Susac syndrome was first described by John O. Susac in 1979 in two young women with the classic clinical triad. Since then exciting advances have been achieved regarding the clinical and paraclinical characterization of the syndrome and the pathophysiological mechanisms of the disease. Nowadays this syndrome is considered an autoimmune microangiopathy, affecting the precapillary arterioles of the brain, retina, and inner ear. Given the complexity of this syndrome, the creation of formal diagnostic criteria is relevant to improve the diagnostic process. These new criteria also emphasize the necessity of a multidisciplinary approach that includes the combined work of neurologists, neuroradiologists, ophthalmologists and otorhinolaryngologists. Although the primary pathogenic anti-antibody is yet to be discovered, precise immunosuppressive therapy results in significant clinical and radiological improvement, delaying disease progression and neurological disability. Further studies are needed to evaluate the use of these criteria prospectively. However in the meantime these criteria may aid the diagnostic process of patients with suspected Susac syndrome.
As such, this is a very interesting study, which provides valuable insights into the diagnosis of Susac syndrome.
Read more at http://jnnp.bmj.com/content/87/12/1287.full.pdf
31 Oct, 16 | by Dr Jose Manuel Matamala, JNNP web editor.
Since the recognition of antibodies against voltage – gated potassium channel (VGKC) and their pathogenic implication in central nervous system disorders (such as limbic encephalitis) in 2001, critical immunological and neurological advances have been achieved during the last 15 years. One of the main discoveries has been that these VGKC antibodies usually target proteins outside of the channel protein, which are part of the VGKC complex (e.g. contactin-associated protein 2). Moreover, each specific antibody is associated with distinct clinical phenotypes, which commonly overlap.
Clinically the primary neurological syndrome associated with VGKC antibodies is limbic encephalitis, classically presenting with severe memory impairment and secondary hippocampal atrophy. However, recently emerging psychiatric syndromes have been linked to this autoimmune condition.
In the current issue of JNNP, Prüss and Lennox have published a review describing novel psychiatric syndromes associated with VGKC complex antibodies. In the review, the authors described the recent highlights about the pattern of cognitive involvement and reversibility of memory dysfunction in limbic encephalitis, response to treatment with immunotherapy, immunology of VGKC complex antibodies and the relevance of the titre levels, and mood and psychotic disorders associated with VGKC complex antibodies.
Emerging psychiatric syndromes associated with VGKC complex antibodies. Psychiatric symptoms are frequently present in patients with limbic encephalitis secondary to VGKC complex antibodies. However, its role in psychiatric diseases is not well understood.
Although, evidence regarding the pathogenic role of VGKC complex antibodies in psychiatric conditions is missing and many questions remain to be answered in this field, it is important that neurologists and psychiatrists combine their expertise to gain a better comprehension of this neuropsychiatric disorder. It is relevant for neurologists to be aware of psychiatric manifestations associated with autoimmune channelopathies and for psychiatrists to keep in mind that VGKC complex antibodies could be part of the differential diagnosis in patients with atypical psychiatric manifestations and autoimmune features.
Read more at http://jnnp.bmj.com/content/87/11/1242.full
7 Oct, 16 | by Dr Jose Manuel Matamala, JNNP web editor.
In the current issue of JNNP, Gonçalves and colleagues have published a randomized control trial (RCT) comparing melatonin, amitriptyline and placebo for migraine prevention.
Migraine is a chronic neurological disease and has been ranked as the sixth disabling condition by World Health Organization (WHO). The goals of migraine prophylaxis are to reduce migraine attacks, limit the need for analgesic intake and improve the quality of life. However, despite the different pharmacological treatments available, only a small fraction of patients receive adequate preventive treatment, which amongst other reasons is related to unfavourable drug security profile.
In this study, after randomizing 196 patients into melatonin (3 mg), amitriptyline (25 mg) or placebo (randomization ratio 1:1:1) and following up for 12 weeks, the authors reported a significant reduction in the number of migraine headache days per month with melatonin or amitriptyline versus placebo. Even though melatonin and amitriptyline were equally effective for the primary endpoint, the number of patients with greater than 50% reduction in migraine headache days was significantly higher in the melatonin group. Moreover, the number of adverse effects was also significantly lower in this group compared with amitriptyline. These results support the efficacy and tolerability of melatonin as a prophylaxis therapy for migraine.
Melatonin a new therapeutic option for the treatment of migraine patients
Melatonin is a hormone produced mainly in the pineal gland, and it plays an essential role as an endogenous synchronizer of internal circadian rhythms. Melatonin has demonstrated efficacy and safety in the treatment of nociceptive and neuropathic pain in several studies. Specifically in migraine, melatonin receptors have been described in the nuclei of the trigeminal nerve, suggesting that may decrease trigeminovascular nociception. Moreover, melatonin levels have been described to be reduced in migraine patients. Regarding the security profile, melatonin is remarkably well tolerated and it only has minor side effects such as daytime sleepiness, dizziness, and stomach pain. These features make melatonin a good candidate for migraine prophylaxis.
In short, this is an interesting article that has clear and immediate clinical application.
Read more at http://jnnp.bmj.com/content/87/10/1127.full.pdf
29 Aug, 16 | by Dr Jose Manuel Matamala, JNNP web editor.
In the current issue of JNNP, Iwadate and colleagues investigated the correlation between the changes in 11C-methionine positron emission tomography (PET) and the 1p/19q status in oligodendroglial tumours.
Gliomas are the most common primary brain tumour in adults. Typically, based in the histological classification, gliomas have been classified into two major subgroups: (i) astrocytic tumours and (ii) oligodendroglial tumours. This differentiation is not trivial given that oligodendroglial tumours are more sensitive to radiotherapy and chemotherapy and are associated with better prognosis. Among the new molecular biomarkers used in the stratification of gliomas, the chromosome 1p/19q deletion has been established as a prognostic and predictive marker in oligodendroglial tumours.
In this study, the authors retrospectively reviewed 66 cases with grade II or III oligodendroglioma or oligoastrocytoma that were studied by 11C-methionine PET and fluorescence in situ hybridisation to defined the 1p/19q status. The tissue uptake of 11C-methionine was expressed as a ratio of tumour to normal tissue (T/N) of the standardized uptake values (SUV). The T/N ratio was higher in grade III oligodendroglial tumours than in grade II tumours. The mean T/N ratio was significantly higher in the 1p/19q non-deleted tumours than the tumours with the deletion in grade II and grade III oligodendroglial tumours. These changes were not associated with cell density or Ki-67 labelling index. The authors conclude that among suspected oligodendroglial tumours 11C-methionine PET could be helpful to stratify preoperatively tumours with and without 1p/19q deletion.
1p/19q status in oligodendroglial tumours with 11C-methionine PET. In this study, tissue uptake of 11C-methionine was significantly higher in the 1p/19q non-deleted tumours than the tumours with the deletion.
This article contributes to the non-invasive and preoperative characterization of biological biomarkers for oligodendroglial tumours. The knowledge of the molecular signature in gliomas stratification is more crucial than ever. The WHO Classification of Tumours of the Central Nervous System has been recently modified1. For the first time, the WHO classification uses molecular parameters in addition to histopathological features to define brain tumours. Now the diagnosis of oligodendroglioma and anaplastic oligodendroglioma thus involves the demonstration of both an IDH mutation and the 1p/19q deletion.
Clearly, the knowledge of the molecular fingerprint of oligodendroglial tumours using non-invasive imaging techniques could improve the planning of neuro-oncological treatments and may help define future pre-surgical therapeutics options in tumours with specific molecular markers.
Read more at http://jnnp.bmj.com/content/87/9/1016.full.pdf
- Louis DN, Perry A, Reifenberger G, et al. The 2016 World Health Organization Classification of Tumors of the Central Nervous System: a summary. Acta Neuropathol. 2016 Jun;131(6):803-20.
28 Jul, 16 | by Dr Jose Manuel Matamala, JNNP web editor.
In the current issue of JNNP, Watanabe and colleagues published a genome-wide association study (GWAS) in ALS to explore the effects of genetic variants in the disease course of sporadic ALS patients.
ALS is an incurable neurodegenerative disease that affects the motor neurons in the cortex, brainstem, and spinal cord, typically resulting in death within 2 – 3 years. Even though enormous advances in the comprehension of the disease have been achieved during the last decade, the huge clinical and genetic heterogeneity of the disease have hindered the development of new disease-modifying treatments. With the aim to explore the heterogeneity across ALS spectrum, a number of GWAS using large-scale genotyping of single nucleotide polymorphisms (SNPs) have failed to generate consistent results and reported associations were not strong enough to develop suitable disease models.
In the study, Watanabe and colleagues explore the impact of genetic variants (SNPs) in different patterns of functional decline in patients with sporadic ALS. A total of 465 ALS patients were clustered according to the longitudinal functional score (ALSFRS-R) in four groups: a rapid decline cluster, an intermediate decline cluster, a sigmoidal decline cluster and a moderate decline cluster. Amongst the 572.983 SNPs studied using genome-wide analysis, seven SNPs were associated with the rapid decline cluster (odds ratio: 5.5 to 5.84). Specifically, homozygosity for the minor alleles of the seven SNPs (linkage disequilibrium block) was associated with decreased expression of TNN (the gene that encodes Titin, a sarcomere protein). Finally, the authors described down-regulation of Titin in immortalised lymphocytes lines from such patients with ALS.
Titin associated SNPs and rapid functional decline in patients with ALS. In this GWAS study, seven SNPs were associated with the rapid functional decline cluster. These SPNs are linked to decreased expression of Tilin, a sarcomere protein that plays important roles in muscle function.
The studying of the genetic factors that influence the clinical course of ALS is extremely valuable in the design of new clinical trials. This study is the first that identifies genetic factors associated with rapid functional decline in sporadic ALS patients. The seven SNPs related to functional decline were associated to decreased Titin expression, an essential sarcomere protein. These results may suggest that Titin determines ALS disease progression through its role in muscle function. Previous studies have related Titin with different myopathies (e.g. limb-girdle muscle dystrophy). Given that there are not previous studies of Titin in ALS, these results represent a new opportunity to explore the role of Titin in ALS pathogenesis. From a clinical point of view, the impact of Tinin on the clinical disease course must be confirmed in future prospective studies, which must explore these genetic variants in ALS patients with different genetic backgrounds.
Finally, it is clear that this study provides a new candidate that might help to understand the complex heterogeneity behind the ALS spectrum.
Read more at http://jnnp.bmj.com/content/87/8/851.full.pdf
9 Jul, 16 | by Dr Jose Manuel Matamala, JNNP web editor.
In the current issue of JNNP, Vanli-Yavuz and colleagues published the largest systematic screening study of neuronal autoantibodies in mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS). Of relevance to the study, epilepsy is a prevalent neurological disorder affecting over 50 million people worldwide. Despite all the advances in this field, it is estimated that around 30% of all patients with epilepsy are refractory to antiepileptic treatment, MTLE-HS being one of the major causes of intractable epilepsy. Different mechanisms have been related to the development of this disease including a possible autoimmune dysfunction among others.
Returning to the study by Vanli-Yavuz and colleagues, the authors studied the prevalence of different neuronal autoantibodies in a large series of 111 patients with MTLE-HS and compared with 80 control subjects (30 healthy subjects and 50 patient with relapsing-remitting multiple sclerosis) (http://jnnp.bmj.com/content/87/7/684.full). Interestingly, they found the presence of neuronal autoantibodies in 22.5% of MTLE-HS patients principally against the VGKC-complex. The healthy and disease control group did not show any neuronal autoantibodies. The presence of neuronal autoantibodies was associated with a history of status epilepticus, diagnosis of psychosis, and involvement of temporal and extra-temporal regions on PET/SPECT studies. In addition, specifically, the VGKC-complex patient’s subgroup also was associated with cognitive dysfunction. Surprisingly, unexplained remission (either spontaneous or following antiepileptic drugs) was significantly more frequent in the seropositive group (28% vs 3.5%). Finally, the authors reported the absence of inflammatory activity in brain tissue from 7 operated seropositive patients.
Neuronal autoantibodies in mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS). In this study, approximately one-fourth of the patients showed seropositivity to neuronal autoantibodies, principally against the VGKC-complex.
Given the prevalence and the complex treatment approaches to MTLE-HS, the findings in this article seem highly relevant in the future consideration of immunomodulatory therapies in these patients. However, before this can happen, there are still many questions that need to be critically addressed. For instance, What is the role of these neuronal autoantibodies in MTLE-HS pathogenesis? Are they pathogenic or are they the consequence of neuronal destruction? Why are these neuronal autoantibodies associated with patients with unexplained remission?. Clearly, further studies will be needed to answer some of these questions. Nevertheless, this study provides hope to improve our understanding of this disease and suggest a new skyline for this neurological disease.
Well worth the read!!
21 Apr, 16 | by Arun Krishnan, Web Editor
Arun Krishnan and Steve Vucic, Neurologists and JNNP web editors, discuss recent data on possible Zika virus-induced neurological disease.
There has been considerable worldwide coverage documenting the impact of the recent Zika virus epidemic which spread through South America and more recently the Carribean. While infection with Zika is of little consequence in most people but there have been major concerns with infection in pregnant women and most of the interest has focussed on the nervous system. The most marked congenital neurological abnormality has been the development of microcephaly in newborns and this was most clearly brought out in the large spike in cases of microcephaly in Brazil in 2016. There have however been concerns about attributing causality based on epidemiological data alone and a recent paper in the New England Journal of Medicine noted that there were methodological concerns in some of the studies and that it may be premature to invoke causality . A more recent report in the same journal has laid out the case for and against a causal effect . In this paper, the authors test current scientific knowledge concerning Zika against accepted criteria for proof of human teratogenicity. Interestingly, the case for causality appears strong when assessed in this manner. Of note, the spike in cases of microcephaly in South America was not the first time that it has been associated with a Zika outbreak: a previous Zika epidemic in French Polynesia in 2013-2014 was also associated with an increase in microcephaly. In both South America and French Polynesia, the Zika outbreak preceded the spike in microcephaly cases and neonates who were affected also manifested other signs that are consistent with Zika exposure. The authors also provide references to studies that have outlined the mechanisms of Zika-induced neurotoxicity, with changes noted in neural progenitor cells that are exposed to the virus, providing evidence of biological plausibility.
In addition to the neonatal neurological manifestations, Zika virus infections have been associated with the occurrence of Guillain Barre Syndrome (GBS) [3-7], an acute immune-mediatied polyradiculoneuropathy with a heterogeneous phenotype, that causes acute weakness and impaired sensation. The first case of ZIKA related GBS was reported in 2013 in a French Polynesian lady, clinically presenting as global tetraparesis, facial paralysis, and autonomic nervous system dysfunction. Subsequently, a further 42 GBS cases secondary to Zika virus infection have been reported, with Zika virus infection preceding the onset of GBS by 6 days . Most patients exhibited a rapid disease course, severe tetraparesis and bilateral facial weakness, with an elevated CSF protein level. Respiratory dysfunction, requiring intensive care management, was evident in 38% of patients, although all responded to therapy with intravenous immunoglobulin or plasmapheresis. Importantly, no patients died as a result of Zika virus infection related GBS, and over half the patients exhibited good clinical recovery at 3 months post infection. Neurophysiological studies disclosed a predominantly distal demyelinating motor neuropathy which improved on follow-up . The pathophysiological mechanisms by which Zika virus infection underlies the development of GBS remains to be fully elucidated, although antigenic mimicry against yet to be identified axonal targets, or direct viral infection of nerves has been invoked. Given the rapid reversal of clinical and neurophysiological findings, the possibility of an antibody-mediated blockade of nodal Na+ channels leading to failure of distal neurotransmission, should also be explored.
In conclusion, Zika virus infections can lead to severe neurological syndromes including neonatal microcephaly and GBS. Since the Zika virus infection is spreading rapidly across the South America countries, physicians need to be vigilant about the possibility of neurological sequalae and resources need to be allocated to the management of neurological complications of Zika virus infection.
- Broutet N, Krauer F, Riesen M, Khalakdina A, Almiron M, Aldighieri S, et al. Zika Virus as a Cause of Neurologic Disorders. The New England journal of medicine. 2016. Epub 2016/03/10. doi: 10.1056/NEJMp1602708. PubMed PMID: 26959308.
- Rasmussen SA, Jamieson DJ, Honein MA, Petersen LR. Zika Virus and Birth Defects – Reviewing the Evidence for Causality. The New England journal of medicine. 2016. Epub 2016/04/14. doi: 10.1056/NEJMsr1604338. PubMed PMID: 27074377.
- Roze B, Najioullah F, Ferge JL, Apetse K, Brouste Y, Cesaire R, et al. Zika virus detection in urine from patients with Guillain-Barre syndrome on Martinique, January 2016. Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin. 2016;21(9). Epub 2016/03/12. doi: 10.2807/1560-7917.es.2016.21.9.30154. PubMed PMID: 26967758.
- Oehler E, Watrin L, Larre P, Leparc-Goffart I, Lastere S, Valour F, et al. Zika virus infection complicated by Guillain-Barre syndrome–case report, French Polynesia, December 2013. Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin. 2014;19(9). Epub 2014/03/15. PubMed PMID: 24626205.
- Cao-Lormeau VM, Blake A, Mons S, Lastere S, Roche C, Vanhomwegen J, et al. Guillain-Barre Syndrome outbreak associated with Zika virus infection in French Polynesia: a case-control study. Lancet. 2016. Epub 2016/03/08. doi: 10.1016/s0140-6736(16)00562-6. PubMed PMID: 26948433.
- Anaya JM, Ramirez-Santana C, Salgado-Castaneda I, Chang C, Ansari A, Gershwin ME. Zika virus and neurologic autoimmunity: the putative role of gangliosides. BMC medicine. 2016;14(1):49. Epub 2016/03/24. doi: 10.1186/s12916-016-0601-y. PubMed PMID: 27001187; PubMed Central PMCID: PMCPmc4802632.
- Araujo LM, Ferreira ML, Nascimento OJ. Guillain-Barre syndrome associated with the Zika virus outbreak in Brazil. Arq Neuropsiquiatr. 2016;74(3):253-5. Epub 2016/04/07. doi: 10.1590/0004-282×20160035. PubMed PMID: 27050856.
- Vucic S, Kiernan MC, Cornblath DR. Guillain-Barre syndrome: an update. J Clin Neurosci. 2009;16(6):733-41. Epub 2009/04/10. doi: S0967-5868(08)00527-4 [pii]10.1016/j.jocn.2008.08.033 [doi]. PubMed PMID: 19356935.
9 Sep, 15 | by Arun Krishnan, Web Editor
Confusion is a common enough symptom in clinical practice. Often, it can be attributed to systemic conditions, such as medication side effects or infection. Occasionally however, one can be caught out in a situation where a patient develops confusion that is due to a more sinister and rare cause. Encephalitis is a rare cause of confusion but it is important to recognise as early treatment is the key to preventing disability. While viral forms of encephalitis are well recognised, more recently the possibility of immune-mediated encephalitis due to circulating antibodies has begun to emerge as an important cause of encephalitis. Often these disorders occur in the presence of a remote malignancy, such as lung or ovarian cancer and often the neurological diagnosis is the first sign of the malignancy.
In the present issue of JNNP, Onugoren and colleagues have published a series of cases of encephalitis due to unusual antibodies http://jnnp.bmj.com/content/86/9/965.abstract . In their series, patients developed a form of encephalitis known as limbic encephalitis, due to GABA and AMPA receptor antibodies. Lung cancer was subsequently diagnosed in a number of their patients. Interestingly, immune treatments led to improvements in the neurological status of a number of these patients.
This is an interesting paper on a rare but emerging form of encephalitis. The diagnostic and treatment insights are particularly interesting for neurologists everywhere.
29 Jul, 15 | by Arun Krishnan, Web Editor
Some readers will no doubt have watched the 1990 movie, Awakenings starring Robin Williams and Robert de Niro, about a group of patients who had suffered a form of encephalitis and survived, only to be permanently in a state of reduced awareness and responsiveness. The movie was based on a book by the famous neurologist, Oliver Sacks, and explores the potential use of a new treatment for these patients. In his memoir of the same name, Sacks was referring to the possible beneficial effects of L-DOPA, a medication that is first-line treatment for Parkinson’s Disease. That book was written 40 years ago, so what have we learnt since then about this condition?
In this issue of JNNP, Wijemanne and Jankovic have reviewed this topic and have provided an insightful update on this condition http://jnnp.bmj.com/content/86/8/825.full . As noted in their review, catatonia can occur in numerous conditions, both neurological and psychiatric, and it is no longer regarded purely as a form of schizophrenia. In addition, there are a number of systemic conditions in which it can occur including cardiovascular, renal and connective tissue disorders. It can also occur as an adverse reaction to numerous medications.
While the exact pathophysiology remains unclear, the role of changes in GABA neurotransmission have been explored in depth and Zolpidem, a GABA-agonist, has been suggested as a possible treatment. Electroconvulsive therapy (ECT) remains a very potent treatment for this condition and neuroleptic medications are also trialled in some patients. However, as noted in their review, the question of why this occurs remains unresolved and is a question for future research.