|Other names||Catatonic syndrome|
|A patient in catatonic stupor|
|Symptoms||Immobility, mutism, staring, posturing, rigidity, etc.|
|Complications||Physical trauma, malignant catatonia (autonomic instability, life-threatening), dehydration, pneumonia, pressure ulcers due to immobility, muscle contractions, DVT, PE.|
|Causes||Underlying illness (psychiatric, neurologic, or medical), certain drugs/medications|
|Diagnostic method||Clinical, Lorazepam challenge|
|Treatment||Benzodiazepines (lorazepam challenge), ECT|
Catatonia is a neuropsychiatric behavioral syndrome that is characterized by abnormal movements, immobility, abnormal behaviors, and withdrawal. The onset of catatonia can be acute or subtle and symptoms can wax, wane, or change during episodes. There are several subtypes of catatonia: akinetic catatonia, excited catatonia, malignant catatonia, and other forms.
Although catatonia has historically been related to schizophrenia (catatonic schizophrenia), catatonia is most often seen in mood disorders. It is now known that catatonic symptoms are nonspecific and may be observed in other mental, neurological, and medical conditions. Catatonia is not a stand-alone diagnosis (although some experts disagree), and the term is used to describe a feature of the underlying disorder.
Recognizing and treating catatonia is very important as failure to do this can lead to poor outcomes and can be potentially fatal. Treatment with benzodiazepines or ECT can lead to remission of catatonia. There is growing evidence of the effectiveness of the NMDA receptor antagonists amantadine and memantine for benzodiazepine-resistant catatonia. Antipsychotics are sometimes employed, but they can worsen symptoms and have serious adverse effects.
Catatonia is almost always secondary to another underlying illness, often a psychiatric disorder. Mood disorders such as a bipolar disorder and depression are the most common etiologies to progress to catatonia. Other psychiatric associations include schizophrenia and other primary psychotic disorders. It also is related to autism spectrum disorders.
Catatonia is also seen in many medical disorders, including infections (such as encephalitis), autoimmune disorders, meningitis, focal neurological lesions (including strokes), alcohol withdrawal, abrupt or overly rapid benzodiazepine withdrawal, cerebrovascular disease, neoplasms, head injury, and some metabolic conditions (homocystinuria, diabetic ketoacidosis, hepatic encephalopathy, and hypercalcaemia).
Catatonia has been mostly studied in acutely ill psychiatric patients. Catatonia frequently goes unrecognized, leading to the belief that the syndrome is rare, however, this is not true and prevalence has been reported to be as high as 10% in patients with acute psychiatric illnesses. 21-46% of all catatonia cases can be attributed to a general medical condition.
The pathophysiology that leads to catatonia is still poorly understood and a definite mechanism remains unknown. Neurologic studies have implicated several pathways, however, it remains unclear whether these findings are the cause or the consequence of the disorder.
Signs and symptoms
The presentation of a patient with catatonia varies greatly depending on the subtype, underlying cause and it can be acute or subtle.
Because most patients with catatonia have an underlying psychiatric illness, the majority will present with worsening depression, mania, or psychosis followed by catatonia symptoms. Catatonia presents as a motor disturbance in which patients will display marked reduction in movement, marked agitation, or a mixture of both despite having the physical capacity to move normally. These patients may be unable to start an action or stop one. Movements and mannerisms may be repetitive, or purposeless.
The most common signs of catatonia are immobility, mutism, withdrawal and refusal to eat, staring, negativism, posturing (rigidity), rigidity, waxy flexibility/catalepsy, stereotypy (purposeless, repetitive movements), echolalia or echopraxia, verbigeration (repeat meaningless phrases). It should not be assumed that patients presenting with catatonia are unaware of their surroundings as some patients can recall in detail their catatonic state and their actions.
There are several subtypes of catatonia and they are characterized by the specific movement disturbance and associated features. Although catatonia can be divided into various subtypes, the natural history of catatonia is often fluctuant and different states can exist within the same individual.
Retarded/Withdrawn Catatonia: This form of catatonia is characterized by decreased response to external stimuli, immobility or inhibited movement, mutism, staring, posturing, and negativism. Patients may sit or stand in the same position for hours, may hold odd positions, and may resist movement of their extremities.
Excited Catatonia: Excited catatonia is characterized by odd mannerisms/gestures, performing purposeless or inappropriate actions, excessive motor activity restlessness, stereotypy, impulsivity, agitation, combativeness. Speech and actions may be repetitive or mimic another person's. People in this state are extremely hyperactive and may have delusions and hallucinations. Catatonic excitement is commonly cited as one of the most dangerous mental states in psychiatry.
Malignant Catatonia: Malignant catatonia is a life-threatening condition that may progress rapidly within a few days. It is characterized by fever, abnormalities in blood pressure, heart rate, respiratory rate, diaphoresis (sweating), and delirium. Certain lab findings are common with this presentation, however, they are nonspecific which means that they are also present in other conditions and do not diagnose catatonia. These lab findings include: leukocytosis, elevated creatine kinase, low serum iron. The signs and symptoms of malignant catatonia overlap significantly with neuroleptic malignant syndrome (NMS) and so a careful history, review of medications, and physical exam are critical to properly differentiate these conditions. For example, if the patient has waxy flexibility and holds a position against gravity when passively moved into that position, then it is likely catatonia. If the patient has a “lead-pipe rigidity” then NMS should be the prime suspect.
There is not yet a definitive consensus regarding diagnostic criteria of catatonia. In the American Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) and the World Health Organization's eleventh edition of the International Classification of Disease (ICD-11) the classification is more homogeneous than in earlier editions. Prominent researchers in the field have other suggesions for diagnostic criteria.
The DSM-5 does not classify catatonia as an independent disorder, but rather it classifies it as catatonia associated with another mental disorder, due to another medical condition, or as unspecified catatonia. Catatonia is diagnosed by the presence of three or more of the following 12 psychomotor symptoms in association with the above-mentioned mental disorder, medical condition, or unspecified.
- stupor: no psycho-motor activity; not actively relating to environment
- catalepsy: passive induction of a posture held against gravity
- waxy flexibility: allowing positioning by examiner and maintaining that position
- mutism: no, or very little, verbal response (exclude if known aphasia)
- negativism: opposition or no response to instructions or external stimuli
- posturing: spontaneous and active maintenance of a posture against gravity
- mannerisms that are odd, circumstantial caricatures of normal actions
- stereotypy: repetitive, abnormally frequent, non-goal-directed movements
- agitation, not influenced by external stimuli
- grimacing: keeping a fixed facial expression
- echolalia: mimicking another's speech
- echopraxia: mimicking another's movements.
Other disorders (additional code 293.89 [F06.1] to indicate the presence of the co-morbid catatonia):
- Catatonia associated with autism spectrum disorder
- Catatonia associated with schizophrenia spectrum and other psychotic disorders
- Catatonia associated with bipolar and related disorders
- Catatonia associated with major depressive disorder
- Catatonic disorder due to another medical condition
In ICD-11 catatonia is defined as a syndrome of primarily psychomotor disturbances that is characterised by the simultaneous occurrence of several symptoms such as stupor; catalepsy; waxy flexibility; mutism; negativism; posturing; mannerisms; stereotypies; psychomotor agitation; grimacing; echolalia and echopraxia. Catatonia may occur in the context of specific mental disorders, including mood disorders, schizophrenia or other primary psychotic disorders, and Neurodevelopmental disorders, and may be induced by psychoactive substances, including medications. Catatonia may also be caused by a medical condition not classified under mental, behavioural, or neurodevelopmental disorders.
Catatonia is often overlooked and under-diagnosed. Patients with catatonia most commonly have an underlying psychiatric disorder, for this reason, physicians may overlook signs of catatonia due to the severity of the psychosis the patient is presenting with. Furthermore, the patient may not be presenting with the common signs of catatonia such as mutism and posturing. Additionally, the motor abnormalities seen in catatonia are also present in psychiatric disorders. For example, a patient with mania will show increased motor activity that may progress to excited catatonia. One way in which physicians can differentiate between the two is to observe the motor abnormality. Patients with mania present with increased goal-directed activity. On the other hand, the increased activity in catatonia is not goal-directed and often repetitive.
Catatonia is a clinical diagnosis and there is no specific laboratory test to diagnose it. However, certain testing can help determine what is causing the catatonia. An EEG will likely show diffuse slowing. If a seizure activity is driving the syndrome, then an EEG would also be helpful in detecting this. CT or MRI will not show catatonia; however, they might reveal abnormalities that might be leading to the syndrome. Metabolic screens, inflammatory markers, or autoantibodies may reveal reversible medical causes of catatonia.
Vital signs should be frequently monitored as catatonia can progress to malignant catatonia which is life-threatening. Malignant catatonia is characterized by fever, hypertension, tachycardia, and tachypnea.
Various rating scales for catatonia have been developed, however, their utility for clinical care has not been well established. The most commonly used scale is the Bush-Francis Catatonia Rating Scale (BFCRS) (external link is provided below). The scale is composed of 23 items with the first 14 items being used as the screening tool. If 2 of the 14 are positive, this prompts for further evaluation and completion of the remaining 9 items.
A diagnosis can be supported by the lorazepam challenge or the zolpidem challenge. While proven useful in the past, barbiturates are no longer commonly used in psychiatry; thus the option of either benzodiazepines or ECT.
The initial treatment of catatonia is to stop medication that could be potentially leading to the syndrome. These may include steroids, stimulants, anticonvulsants, neuroleptics, dopamine blockers, etc. The next step is to provide a “lorazepam challenge,” in which patients are given 2 mg of IV lorazepam (or another benzodiazepine). Most patients with catatonia will respond significantly to this within the first 15–30 minutes. If no change is observed during the first dose, then a second dose is given and the patient is re-examined. If the patient responds to the lorazepam challenge, then lorazepam can be scheduled at interval doses until the catatonia resolves. The lorazepam must be tapered slowly, otherwise, the catatonia symptoms may return. The underlying cause of the catatonia should also be treated during this time. If within a week the catatonia is not resolved, then ECT can be used to reverse the symptoms. ECT in combination with benzodiazepines is used to treat malignant catatonia. In France, zolpidem has also been used in diagnosis, and response may occur within the same time period. Ultimately the underlying cause needs to be treated.
Electroconvulsive therapy (ECT) is an effective treatment for catatonia that is well acknowledged. ECT has also shown favorable outcomes in patients with chronic catatonia. However, it has been pointed out that further high quality randomized controlled trials are needed to evaluate the efficacy, tolerance, and protocols of ECT in catatonia.
Antipsychotics should be used with care as they can worsen catatonia and are the cause of neuroleptic malignant syndrome, a dangerous condition that can mimic catatonia and requires immediate discontinuation of the antipsychotic.
Excessive glutamate activity is believed to be involved in catatonia; when first-line treatment options fail, NMDA antagonists such as amantadine or memantine may be used. Amantadine may have an increased incidence of tolerance with prolonged use and can cause psychosis, due to its additional effects on the dopamine system. Memantine has a more targeted pharmacological profile for the glutamate system, reduced incidence of psychosis and may therefore be preferred for individuals who cannot tolerate amantadine. Topiramate is another treatment option for resistant catatonia; it produces its therapeutic effects by producing glutamate antagonism via modulation of AMPA receptors.
Complications, outcomes, and recurrence
Patients may suffer several complications from being in a catatonic state. The nature of these complications will depend on the type of catatonia being experienced by the patient. For example, patients presenting with retarded catatonia may have refusal to eat which will in turn lead to malnutrition and dehydration. Furthermore, if immobility is a symptom the patient is presenting with, then they may develop pressure ulcers, muscle contractions, and are at risk of developing deep vein thrombosis (DVT) and pulmonary embolus (PE). Patients with excited catatonia may be aggressive and violent, and physical trauma may result from this. Catatonia may progress to the malignant type which will present with autonomic instability and may be life-threatening. Other complications also include the development of pneumonia and neuroleptic malignant syndrome.
Patients who experience an episode of catatonia are more likely to suffer recurrence. Treatment response for patients with catatonia is 50-70% and these patients have a good prognosis. However, failure to respond to medication is a very poor prognosis. Many of these patients will require long-term and continuous mental health care. For patients with catatonia with underlying schizophrenia, the prognosis is much poorer.
The differential diagnosis of catatonia is extensive as signs and symptoms of catatonia may overlap significantly with those of other conditions. Therefore, a careful and detailed history, medication review, and physical exam are key to diagnosing catatonia and differentiating it from other conditions. Furthermore, some of these conditions can themselves lead to catatonia. The differential diagnosis is as follows:
--Neuroleptic malignant syndrome (NMS): Malignant catatonia and NMS are both life-threatening conditions that share many of the same characteristics including fever, autonomic instability, rigidity, and delirium. Lab values of low serum iron, elevated creatine kinase, and white blood cell count are also shared by the two disorders further complicating the diagnosis. There are features of malignant catatonia (posturing, impulsivity, etc.) that are absent from NSM and the lab results are not as consistent in malignant catatonia as they are in NMS. Some experts consider NMS to be a drug-induced condition associated with antipsychotics, particularly, first generation antipsychotics, but it has not been established as a subtype. Therefore, discontinuing antipsychotics and starting benzodiazepines is a treatment for this condition, and similarly it is helpful in catatonia as well.
--Anti-NMDA receptor encephalitis: Anti-NMDA receptor encephalitis is an autoimmune disorder characterized by neuropsychiatric features and the presence of IgG antibodies. The presentation of anti-NMDAR encephalitis has been categorized into 5 phases: prodromal phase, psychotic phase, unresponsive phase, hyperkinetic phase, and recovery phase. The psychotic phase progresses into the unresponsive phase characterized by mutism, decreased motor activity, and catatonia.
--Serotonin syndrome: Both serotonin syndrome and malignant catatonia may present with signs and symptoms of delirium, autonomic instability, hyperthermia, and rigidity. Again, similar to the presentation in NSM. However, patients with Serotonin syndrome have a history of ingestion of serotonergic drugs (Ex: SSRI). These patients will also present with hyperreflexia, myoclonus, nausea, vomiting, and diarrhea.
--Malignant hyperthermia: Malignant hyperthermia and malignant catatonia share features of autonomic instability, hyperthermia, and rigidity. However, malignant hyperthermia is a hereditary disorder of skeletal muscle that makes these patients susceptible to exposure to halogenated anesthetics and/or depolarizing muscle relaxants like succinylcholine. Malignant hyperthermia most commonly occurs in the intraoperative or postoperative periods. Other signs and symptoms of malignant hyperthermia include metabolic and respiratory acidosis, hyperkalemia, and cardiac arrhythmias.
--Akinetic mutism: Akinetic mutism is a neurological disorder characterized by a decrease in goal-directed behavior and motivation, however, the patient has an intact level of consciousness. Patients may present with apathy, and may seem indifferent to pain, hunger, or thirst. Akinetic mutism has been associated with structural damage in a variety of brain areas. Akinetic mutism and catatonia may both manifest with immobility, mutism, and waxy flexibility. Differentiating both disorders is the fact that akinetic mutism does not present with echolalia, echopraxia, or posturing. Furthermore, it is not responsive to benzodiazepines as is the case for catatonia.
--Elective mutism: Elective mutism has an anxious etiology but has also been associated with personality disorders. Patients with this disorder fail to speak with some individuals but will speak with others. Likewise, they may refuse to speak in certain situations, for example, a child who refuses to speak at school but is conversational at home. This disorder is distinguished from catatonia by the absence of any other signs/symptoms.
--Nonconvulsive status epilepticus: Nonconvulsive status epilepticus is seizure activity with no accompanying tonic-clonic movements. It can present with stupor, similar to catatonia, and they both respond to benzodiazepines. Nonconvulsive status epilepticus is diagnosed by the presence of seizure activity seen on electroencephalogram (EEG). Catatonia on the other hand, is associated with normal EEG or diffuse slowing.
--Delirium: Delirium is characterized by fluctuating disturbed perception and consciousness in the ill individual. It has hypoactive and hyperactive or mixed forms. People with hyperactive delirium present similarly to those with excited catatonia and have symptoms of restlessness, agitation and aggression. Those with hypoactive delirium present with similarly to retarded catatonia, withdrawn and quiet. However, catatonia also includes other distinguishing features including posturing and rigidity as well as a positive response to benzodiazepines.
--Locked-in syndrome: Patients with locked-in syndrome present with immobility and mutism, however, unlike patients with catatonia who are unmotivated to communicate, patients with locked-in syndrome try to communicate with eye movements and blinking. Furthermore, locked-in syndrome is caused by damage to the brainstem.
--Stiff-person syndrome: Catatonia and stiff-person syndrome are similar in that they may both present with rigidity, autonomic instability and a positive response to benzodiazepines. However, stiff-person syndrome may be associated with anti-glutamic acid decarboxylase (anti-GAD) antibodies and other catatonic signs such as mutism and posturing are not part of the syndrome.
--Parkinson's disease: Untreated late-stage Parkinson's disease may present similarly to retarded catatonia with symptoms of immobility, rigidity, and difficulty speaking. Further complicating the diagnosis is the fact that many patients with Parkinson's disease will have major depressive disorder which may be the underlying cause of catatonia. Parkinson's disease can be distinguished from catatonia by a positive response to levodopa. Catatonia on the other hand will show a positive response to benzodiazepines.
- Akinetic mutism
- Autistic catatonia
- Awakenings (1990 biopic about catatonic patients, based on Oliver Sacks's book of the same name)
- Blank expression
- Disorganized schizophrenia
- Homecoming (features catatonia as a main plot point)
- Karolina Olsson
- Oneiroid syndrome
- Paranoid schizophrenia
- Persistent vegetative state
- Resignation syndrome
- Sensory overload
- Tonic immobility
- Sleep paralysis
- Fink, Max; Taylor, Michael Alan (November 2009). "The catatonia syndrome: forgotten but not gone". Archives of General Psychiatry. 66 (11): 1173–1177. doi:10.1001/archgenpsychiatry.2009.141. ISSN 1538-3636. PMID 19884605.
- Burrow, Jeffrey P.; Spurling, Benjamin C.; Marwaha, Raman (2020), "Catatonia", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 28613592, retrieved 6 January 2021
- Fink, Max (July 2009). "Catatonia: a syndrome appears, disappears, and is rediscovered". Canadian Journal of Psychiatry. 54 (7): 437–445. doi:10.1177/070674370905400704. ISSN 1497-0015. PMID 19660165.
- Fink, Max (2011). "Catatonia from its creation to DSM-V: Considerations for ICD". Indian Journal of Psychiatry. 53 (3): 214–217. doi:10.4103/0019-5545.86810. ISSN 0019-5545. PMC 3221176. PMID 22135438.
- Carroll, Brendan T.; Goforth, Harold W.; Thomas, Christopher; Ahuja, Niraj; McDaniel, William W.; Kraus, Marilyn F.; Spiegel, David R.; Franco, Kathleen N.; Pozuelo, Leopold; Muñoz, Camilo (1 October 2007). "Review of Adjunctive Glutamate Antagonist Therapy in the Treatment of Catatonic Syndromes". The Journal of Neuropsychiatry and Clinical Neurosciences. 19 (4): 406–412. doi:10.1176/jnp.2007.19.4.406. ISSN 0895-0172. PMID 18070843.
- Fink, M.; Taylor, M. A. Catatonia: A Clinician's Guide to Diagnosis and Treatment. Cambridge University Press, 2003.
- "Zur Entwicklung der Psychiatrie - ein Internet-Atlas von Dr. Hans-Peter Haack" (in German). Archived from the original on 9 February 2008. Retrieved 29 June 2017.
- Dhossche, D, et al. Catatonia in Autism Spectrum Disorders. Elsevier, Amsterdam, 2006.
- Rogers, Jonathan P; Pollak, Thomas A; Blackman, Graham; David, Anthony S (July 2019). "Catatonia and the immune system: a review". The Lancet. Psychiatry. 6 (7): 620–630. doi:10.1016/S2215-0366(19)30190-7. ISSN 2215-0366. PMC 7185541. PMID 31196793.
- Haroche, Alexandre; Rogers, Jonathan; Plaze, Marion; Gaillard, Raphaël; Williams, Steve Cr; Thomas, Pierre; Amad, Ali (16 June 2020). "Brain imaging in catatonia: systematic review and directions for future research". Psychological Medicine. 50 (10): 1585–1597. doi:10.1017/S0033291720001853. ISSN 1469-8978. PMID 32539902. S2CID 219704600.
- Geoffroy PA, Rolland B, Cottencin O (May–June 2012). "Catatonia and alcohol withdrawal: a complex and underestimated syndrome". Alcohol Alcohol. 47 (3): 288–90. doi:10.1093/alcalc/agr170. PMID 22278315.
- Rosebush PI; Mazurek MF (August 1996). "Catatonia after benzodiazepine withdrawal". Journal of Clinical Psychopharmacology. 16 (4): 315–9. doi:10.1097/00004714-199608000-00007. PMID 8835707.
- Deuschle M, Lederbogen F (January 2001). "Benzodiazepine withdrawal-induced catatonia". Pharmacopsychiatry. 34 (1): 41–2. doi:10.1055/s-2001-15188. PMID 11229621.
- Kanemoto K, Miyamoto T, Abe R (September 1999). "Ictal catatonia as a manifestation of de novo absence status epilepticus following benzodiazepine withdrawal". Seizure. 8 (6): 364–6. doi:10.1053/seiz.1999.0309. PMID 10512781. S2CID 17454162.
- American Psychiatric Association (2013). Diagnostic and Statistical Manual of Mental Disorders (Fifth ed.). Arlington, VA: American Psychiatric Publishing. pp. 119–121. ISBN 978-0-89042-555-8.
- Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR). 1. 2000. doi:10.1176/appi.books.9780890423349. ISBN 0-89042-334-2.
- Solmi, Marco; Pigato, G Giorgio; Roiter, Beatrice; Guaglianone, Argentina; Martini, Luca; Fornaro, Michele; Monaco, Francesco; Carvalho, Andrè F; Stubbs, Brendon; Veronese, Nicola; Correll, Christoph U (August 2018). "Prevalence of Catatonia and Its Moderators in Clinical Samples: Results from a Meta-analysis and Meta-regression Analysis". Schizophrenia Bulletin. 44 (5): 1133–1150. doi:10.1093/schbul/sbx157. ISSN 0586-7614. PMC 6101628. PMID 29140521.
- Rasmussen, Sean A; Mazurek, Michael F; Rosebush, Patricia I (22 December 2016). "Catatonia: Our current understanding of its diagnosis, treatment and pathophysiology". World Journal of Psychiatry. 6 (4): 391–398. doi:10.5498/wjp.v6.i4.391. ISSN 2220-3206. PMC 5183991. PMID 28078203.
- Serra-Mestres, Jordi; Jaimes-Albornoz, Walter (29 June 2018). "Recognizing Catatonia in Medically Hospitalized Older Adults: Why It Matters". Geriatrics (Basel, Switzerland). 3 (3): 37. doi:10.3390/geriatrics3030037. ISSN 2308-3417. PMC 6319219. PMID 31011075.
- Walther, Sebastian; Stegmayer, Katharina; Wilson, Jo Ellen; Heckers, Stephan (July 2019). "Structure and neural mechanisms of catatonia". The Lancet. Psychiatry. 6 (7): 610–619. doi:10.1016/S2215-0366(18)30474-7. ISSN 2215-0374. PMC 6790975. PMID 31196794.
- Dhossche, Dirk M.; Stoppelbein, Laura; Rout, Ujjwal K. (December 2010). "Etiopathogenesis of catatonia: generalizations and working hypotheses". The Journal of ECT. 26 (4): 253–258. doi:10.1097/YCT.0b013e3181fbf96d. ISSN 1533-4112. PMID 21076339.
- Northoff, G. (July 2000). "Brain imaging in catatonia: current findings and a pathophysiologic model". CNS Spectrums. 5 (7): 34–46. doi:10.1017/s1092852900013377. ISSN 1092-8529. PMID 18197154. S2CID 12837559.
- Northoff, Georg (October 2002). "What catatonia can tell us about "top-down modulation": a neuropsychiatric hypothesis". The Behavioral and Brain Sciences. 25 (5): 555–577, discussion 578–604. doi:10.1017/s0140525x02000109. ISSN 0140-525X. PMID 12958742. S2CID 20407002.
- Zisselman, Marc H.; Jaffe, Richard L. (February 2010). "ECT in the treatment of a patient with catatonia: consent and complications". The American Journal of Psychiatry. 167 (2): 127–132. doi:10.1176/appi.ajp.2009.09050703. ISSN 1535-7228. PMID 20123920.
- Rasmussen, Sean A.; Mazurek, Michael F.; Rosebush, Patricia I. (22 December 2016). "Catatonia: Our current understanding of its diagnosis, treatment and pathophysiology". World Journal of Psychiatry. 6 (4): 391–398. doi:10.5498/wjp.v6.i4.391. ISSN 2220-3206. PMC 5183991. PMID 28078203.
- Shorter, Edward; Fink, Max (2018). The Madness of Fear: A History of Catatonia. Oxford University Press. ISBN 978-0-19-088119-1.
- Nolen-Hoeksema. Abnormal psychology. (6th ed., p. 224)
- Fink, Max (2003). Catatonia : a clinician's guide to diagnosis and treatment. Michael Alan Taylor. Cambridge: Cambridge University Press. ISBN 0-511-06198-6. OCLC 57254202.
- Michael B. First (2013). DSM-5® Handbook of Differential Diagnosis. American Psychiatric Publishing. p. 49. ISBN 978-1-58562-998-5.
- Sienaert, Pascal; Rooseleer, Jonas; De Fruyt, Jürgen (December 2011). "Measuring catatonia: a systematic review of rating scales". Journal of Affective Disorders. 135 (1–3): 1–9. doi:10.1016/j.jad.2011.02.012. ISSN 1573-2517. PMID 21420736.
- Bush, G.; Fink, M.; Petrides, G.; Dowling, F.; Francis, A. (February 1996). "Catatonia. I. Rating scale and standardized examination". Acta Psychiatrica Scandinavica. 93 (2): 129–136. doi:10.1111/j.1600-0447.1996.tb09814.x. ISSN 0001-690X. PMID 8686483. S2CID 20752576.
- Sienaert, Pascal; Dhossche, Dirk M.; Vancampfort, Davy; De Hert, Marc; Gazdag, Gábor (2014). "A Clinical Review of the Treatment of Catatonia". Frontiers in Psychiatry. 5: 181. doi:10.3389/fpsyt.2014.00181. ISSN 1664-0640. PMC 4260674. PMID 25538636.
- Thomas, Pierre; Cottencin, Olivier; Rascle, Claire; Vaiva, Guillaume; Goudemand, Michel; Bieder, Jacques (1 January 2007). "Catatonia in French Psychiatry: Implications of the Zolpidem Challenge Test". Psychiatric Annals. 37 (1). doi:10.3928/00485713-20070101-02. ISSN 0048-5713.
- Daniels, Jessica (2009). "Catatonia: clinical aspects and neurobiological correlates". The Journal of Neuropsychiatry and Clinical Neurosciences. 21 (4): 371–380. doi:10.1176/jnp.2009.21.4.371. ISSN 1545-7222. PMID 19996245.
- Leroy, Arnaud; Naudet, Florian; Vaiva, Guillaume; Francis, Andrew; Thomas, Pierre; Amad, Ali (21 June 2017). "Is electroconvulsive therapy an evidence-based treatment for catatonia? A systematic review and meta-analysis". European Archives of Psychiatry and Clinical Neuroscience. 268 (7): 675–687. doi:10.1007/s00406-017-0819-5. ISSN 0940-1334. PMID 28639007. S2CID 4013882.
- Carroll, BT.; Goforth, HW.; Thomas, C.; Ahuja, N.; McDaniel, WW.; Kraus, MF.; Spiegel, DR.; Franco, KN.; et al. (2007). "Review of adjunctive glutamate antagonist therapy in the treatment of catatonic syndromes". J Neuropsychiatry Clin Neurosci. 19 (4): 406–12. doi:10.1176/appi.neuropsych.19.4.406. PMID 18070843. Archived from the original on 13 December 2007.
- Simon, Leslie V.; Hashmi, Muhammad F.; Callahan, Avery L. (2020), "Neuroleptic Malignant Syndrome", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 29489248, retrieved 12 January 2021
- Northoff, G. (December 2002). "Catatonia and neuroleptic malignant syndrome: psychopathology and pathophysiology". Journal of Neural Transmission. 109 (12): 1453–1467. doi:10.1007/s00702-002-0762-z. ISSN 0300-9564. PMID 12486486. S2CID 12971112.
- Samanta, Debopam; Lui, Forshing (2020), "Anti-NMDA Receptor Encephalitis", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 31869136, retrieved 13 January 2021
- Foong, Ai-Leng; Grindrod, Kelly A.; Patel, Tejal; Kellar, Jamie (October 2018). "Demystifying serotonin syndrome (or serotonin toxicity)". Canadian Family Physician. 64 (10): 720–727. ISSN 1715-5258. PMC 6184959. PMID 30315014.
- Watt, Stacey; McAllister, Russell K. (2020), "Malignant Hyperthermia", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 28613578, retrieved 12 January 2021
- Arnts, Hisse; van Erp, Willemijn S.; Lavrijsen, Jan C. M.; van Gaal, Simon; Groenewegen, Henk J.; van den Munckhof, Pepijn (May 2020). "On the pathophysiology and treatment of akinetic mutism". Neuroscience and Biobehavioral Reviews. 112: 270–278. doi:10.1016/j.neubiorev.2020.02.006. ISSN 1873-7528. PMID 32044373.
- Ackermann, H.; Ziegler, W. (February 1995). "[Akinetic mutism--a review of the literature]". Fortschritte der Neurologie-Psychiatrie. 63 (2): 59–67. doi:10.1055/s-2007-996603. ISSN 0720-4299. PMID 7705740.
- Holka-Pokorska, Justyna; Piróg-Balcerzak, Agnieszka; Jarema, Marek (30 April 2018). "The controversy around the diagnosis of selective mutism - a critical analysis of three cases in the light of modern research and diagnostic criteria". Psychiatria Polska. 52 (2): 323–343. doi:10.12740/PP/76088. ISSN 2391-5854. PMID 29975370.
- Wylie, Todd; Sandhu, Divyajot S.; Goyal, Amandeep; Murr, Najib (2020), "Status Epilepticus", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 28613459, retrieved 13 January 2021
- Sutter, Raoul; Kaplan, Peter W. (August 2012). "Electroencephalographic criteria for nonconvulsive status epilepticus: synopsis and comprehensive survey". Epilepsia. 53 Suppl 3: 1–51. doi:10.1111/j.1528-1167.2012.03593.x. ISSN 1528-1167. PMID 22862158. S2CID 24014621.
- Delirium: prevention, diagnosis and management. National Institute for Health and Care Excellence: Clinical Guidelines. London: National Institute for Health and Care Excellence (UK). 2019. ISBN 978-1-4731-2992-4. PMID 31971702.
- M Das, Joe; Anosike, Kingsley; Asuncion, Ria Monica D. (2020), "Locked-in Syndrome", StatPearls, Treasure Island (FL): StatPearls Publishing, PMID 32644452, retrieved 13 January 2021
- Balint, Bettina; Meinck, Hans-Michael (July 2018). "Pragmatic Treatment of Stiff Person Spectrum Disorders". Movement Disorders Clinical Practice. 5 (4): 394–401. doi:10.1002/mdc3.12629. ISSN 2330-1619. PMC 6174384. PMID 30363317.
- Baizabal-Carvallo, José Fidel; Jankovic, Joseph (August 2015). "Stiff-person syndrome: insights into a complex autoimmune disorder". Journal of Neurology, Neurosurgery, and Psychiatry. 86 (8): 840–848. doi:10.1136/jnnp-2014-309201. ISSN 1468-330X. PMID 25511790. S2CID 19981869.
- Sarva, Harini; Deik, Andres; Ullah, Aman; Severt, William L. (2016). "Clinical Spectrum of Stiff Person Syndrome: A Review of Recent Reports". Tremor and Other Hyperkinetic Movements. 6: 340. doi:10.7916/D85M65GD. ISSN 2160-8288. PMC 4790195. PMID 26989571.
- Catatonia in DSM-5
- Encyclopedia of Mental Disorders - Catatonic Disorders
- "Schizophrenia: Catatonic Type" video by Heinz Edgar Lehmann (1911-1999), 1952