Acute Muscle Rigidity Secondary to Tetanus: A Toxicology Simulation Case for Fourth-Year Medical Students.

Introduction: Tetanus is uncommon in the United States secondary to vaccination. However, vaccination hesitancy is increasing. This case challenges medical students to consider tetanus in the differential and understand its complications. Methods: Fourth-year medical students took a pretest on the neurotransmitter glycine and associated disease states. They received two 10-minute lectures on glycine and acid-base abnormalities. Students then participated in a simulation featuring a 27-year-old man bitten by a dog, resulting in tetanus. Required equipment included a mannequin with monitor, a defibrillator, and personal protective equipment. Critical actions consisted of learners dividing up roles amongst each other, using closed-loop communication, placing the patient on a cardiac monitor, choosing to establish IV access and intubate the patient, starting IV fluids, and administering tetanus immunoglobulin. The case ended after 20 minutes. Outcome measurements encompassed performance on a posttest and critical actions. Results: Twenty students participated. Mean pretest and posttest scores were 69.5 and 92.5, respectively (p < .001). All groups completed the items on the critical actions checklist within a 20-minute time frame. Discussion: Rising vaccine hesitancy may increase the likelihood of physicians encountering new cases of tetanus and require them to perform lifesaving management of a patient presenting with muscle rigidity. This simulation provides learners with hands-on experience caring for a patient with tetanus and muscle rigidity. It can improve their knowledge of recognition, assessment, and decision-making toward lifesaving management of tetanus by allowing them to practice their skills in a safe environment.

Schiff-Sherrington phenomenon in a cat with complete spinal cord transection from traumatic dorsocranial luxation of the second lumbar vertebra.

A young stray entire female domestic shorthair cat was presented with symmetrical forelimb extensor rigidity, neck hyperextension and hindlimb paraplegia, characteristic of Schiff-Sherrington phenomenon (SSP), within 30 min of a motor vehicle accident. Radiographic and post-mortem studies disclosed complete transection of the spinal cord from traumatic dorsocranial luxation of the second lumbar vertebra, displacement of the sacrum from the ilium, seventh lumbar and first caudal vertebrae and multiple pelvic fractures. Other causes of forelimb extensor rigidity and neck hyperextension such as decerebrate and decerebellate rigidity were excluded by a lack of neurological signs consistent with these entities and unremarkable findings on post-mortem examination of the cranial cavity and brain and histological examination of the cerebrum, brainstem and cerebellum. To the best of the author's knowledge, this is the first report of SSP in the cat outside the experimental arena of decerebrate or non-decerebrate preparations following post-brachial spinal cord transection/cold block.

[Stiff-Person Syndrome].

Stiff-person syndrome (SPS) is a rare autoimmune neurological disorder characterized by progressive axial muscle stiffness, central nervous system hyper-excitability, and painful stimulus-sensitive muscle spasms. SPS is classified into classic SPS and SPS variants, including stiff-limb syndrome (SLS) and progressive encephalomyelitis with rigidity and myoclonus (PERM), based on clinical presentation. SPS responds to immunotherapy, and several autoantigens have been identified. Most patients with SPS have high-titers of antibodies against glutamic acid decarboxylase (GAD), the rate-limiting enzyme for the synthesis of γ-aminobutyric acid (GABA), and up to 15% of the patients have antibodies against the glycine receptor α-subunit.

Rigidity in Parkinson's disease: evidence from biomechanical and neurophysiological measures.

Although rigidity is a cardinal motor sign in patients with Parkinson's disease (PD), the instrumental measurement of this clinical phenomenon is largely lacking, and its pathophysiological underpinning remains still unclear. Further advances in the field would require innovative methodological approaches able to measure parkinsonian rigidity objectively, discriminate the different biomechanical sources of muscle tone (neural or visco-elastic components), and finally clarify the contribution to 'objective rigidity' exerted by neurophysiological responses, which have previously been associated with this clinical sign (i.e. the long-latency stretch-induced reflex). Twenty patients with PD (67.3 ± 6.9 years) and 25 age- and sex-matched controls (66.9 ± 7.4 years) were recruited. Rigidity was measured clinically and through a robotic device. Participants underwent robot-assisted wrist extensions at seven different angular velocities randomly applied, when ON therapy. For each value of angular velocity, several biomechanical (i.e. elastic, viscous and neural components) and neurophysiological measures (i.e. short and long-latency reflex and shortening reaction) were synchronously assessed and correlated with the clinical score of rigidity (i.e. Unified Parkinson's Disease Rating Scale-part III, subitems for the upper limb). The biomechanical investigation allowed us to measure 'objective rigidity' in PD and estimate the neuronal source of this phenomenon. In patients, 'objective rigidity' progressively increased along with the rise of angular velocities during robot-assisted wrist extensions. The neurophysiological examination disclosed increased long-latency reflexes, but not short-latency reflexes nor shortening reaction, in PD compared with control subjects. Long-latency reflexes progressively increased according to angular velocities only in patients with PD. Lastly, specific biomechanical and neurophysiological abnormalities correlated with the clinical score of rigidity. 'Objective rigidity' in PD correlates with velocity-dependent abnormal neuronal activity. The observations overall (i.e. the velocity-dependent feature of biomechanical and neurophysiological measures of objective rigidity) would point to a putative subcortical network responsible for 'objective rigidity' in PD, which requires further investigation.

High risk and low prevalence diseases: Adult bacterial meningitis.

INTRODUCTION: Acute bacterial meningitis in adults is a rare but serious condition that carries a high rate of morbidity. OBJECTIVE: This review highlights pearls and pitfalls of acute bacterial meningitis in adults, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: Meningitis encompasses a broad spectrum of disease involving inflammation of the meninges and subarachnoid space. It classically presents with fever, nuchal rigidity, and altered mental status, but this triad is not present in all cases. Up to 95% of patients will have at least two of the following four cardinal symptoms: fever, nuchal rigidity, altered mental status, and headache. The most common bacterial etiologies are S. pneumoniae and N. meningitidis. Cerebrospinal fluid testing obtained by lumbar puncture remains the gold standard in diagnosis. Head computed tomography prior to lumbar puncture may not be necessary in most patients. Empiric treatment consists of vancomycin, ceftriaxone, and dexamethasone. Elevated intracranial pressure should be managed using established neurocritical care strategies. CONCLUSION: A better understanding of the pearls and pitfalls of acute bacterial meningitis can assist emergency clinicians in pursuing its timely diagnosis and management.

Fentanyl-induced muscle rigidity in a dog during weaning from mechanical ventilation after emergency abdominal surgery: A case report.

A 22.5-kg, 8.4-year-old female mixed breed dog was presented for an emergency ovariohysterectomy for pyometra. No neurological abnormalities were observed on preoperative physical examination. Surgery was completed uneventfully under fentanyl- and sevoflurane-based anaesthesia. Cardiorespiratory indices remained stable under mechanical ventilation throughout the procedure. Approximately 23 min after the discontinuation of fentanyl infusion, the investigator noticed jaw closure and stiffness and thoraco-abdominal muscle rigidity. To rule out fentanyl-induced muscle rigidity, naloxone was administered. Following administration of naloxone, there was a return of spontaneous respiratory effort, indicated by capnogram and visible chest wall excursion. Based on the clinical signs and response to naloxone administration, the dog was diagnosed with suspected fentanyl-induced muscle rigidity. Six minutes after the return of spontaneous respiration, the dog was extubated uneventfully without additional naloxone administration. During 4 days of postoperative hospitalization, no recurrent muscle rigidity was observed, and the patient was discharged safely. The total dose of fentanyl administered was 0.61 mg (27 µg kg-1 ).

Dantrolene for muscle rigidity in progressive supranuclear palsy.

Progressive supranuclear palsy is a degenerative neurological condition with a high level of associated motor symptom burden manifesting in poor postural reflexes, bradykinesia, dystonia and stiffness in the body core and neck. In the light of a paucity in literature exploring pain management in neurodegenerative diseases, the below case report describes the use of dantrolene to successfully relieve distressing widespread dystonia and muscle rigidity refractory to non-pharmacological and pharmacotherapy. To our knowledge, this is the first reported case of dantrolene use for the treatment of refractory muscle rigidity pain in neurodegenerative conditions.

Neuroleptic malignant syndrome in a postoperative patient: A case report.

Neuroleptic malignant syndrome is a rare medical emergency associated with the use of antipsychotics and other antidopaminergic drugs. There is no specific test, and diagnosis is based on high clinical suspicion and good differential diagnosis. A clinical picture consistent with hyperthermia, muscle rigidity, altered level of consciousness, together with signs of rhabdomyolysis in analytical studies and a history of taking neuroleptic drugs are the key elements in the detection of this entity. Due to its low incidence and potential mortality, it is essential to publish case reports of neuroleptic malignant syndrome in order to raise awareness of this entity and facilitate diagnostic suspicion when encountering a patient with compatible symptoms. The following is the case of a 79 year old patient with chronic alcohol consumption as the only history of interest, who was given a single dose of haloperidol after an episode of delirium in the postoperative period of conventional trauma surgery. She subsequently developed a picture of progressive deterioration of the level of consciousness, diaphoresis, generalized muscle rigidity, hyperthermia, together with severe metabolic acidosis, hyperlacticaemia, rhabdomyolysis, hypertransaminasemia and hypocalcemia. After ruling out other entities compatible with the clinical picture, neuroleptic malignant syndrome was given as the main diagnostic hypothesis. Diagnosis was confirmed after clinical and analytical improvement following treatment with dantrolene. The patient was discharged from hospital with no sequelae a few days after onset of the condition.

Clinical, genetic, and functional characterization of the glycine receptor ß-subunit A455P variant in a family affected by hyperekplexia syndrome.

Hyperekplexia is a rare neurological disorder characterized by exaggerated startle responses affecting newborns with the hallmark characteristics of hypertonia, apnea, and noise or touch-induced nonepileptic seizures. The genetic causes of the disease can vary, and several associated genes and mutations have been reported to affect glycine receptors (GlyRs); however, the mechanistic links between GlyRs and hyperekplexia are not yet understood. Here, we describe a patient with hyperekplexia from a consanguineous family. Extensive genetic screening using exome sequencing coupled with autozygome analysis and iterative filtering supplemented by in silico prediction identified that the patient carries the homozygous missense mutation A455P in GLRB, which encodes the GlyR ß-subunit. To unravel the physiological and molecular effects of A455P on GlyRs, we used electrophysiology in a heterologous system as well as immunocytochemistry, confocal microscopy, and cellular biochemistry. We found a reduction in glycine-evoked currents in N2A cells expressing the mutation compared to WT cells. Western blot analysis also revealed a reduced amount of GlyR ß protein both in cell lysates and isolated membrane fractions. In line with the above observations, coimmunoprecipitation assays suggested that the GlyR α1-subunit retained coassembly with ßA455P to form membrane-bound heteromeric receptors. Finally, structural modeling showed that the A455P mutation affected the interaction between the GlyR ß-subunit transmembrane domain 4 and the other helices of the subunit. Taken together, our study identifies and validates a novel loss-of-function mutation in GlyRs whose pathogenicity is likely to cause hyperekplexia in the affected individual.

Hereditary Hyperekplexia: A New Family and a Systematic Review of GLRA1 Gene-Related Phenotypes.

Hereditary hyperekplexia (HPX) is a genetic neurodevelopmental disorder recently defined by the triad of (1) neonatal hypertonia, (2) excessive startle reflexes, and (3) generalized stiffness following the startle. Defects in GLRA1 are the most common cause of HPX, inherited both in an autosomal dominant and autosomal recessive manner. GLRA1 mutations can also cause milder phenotypes in the startle syndromes spectrum, but the prevalence is uncertain and no clear genotype-phenotype correlation has emerged yet. Moreover, the prevalence of neurodevelopmental outcomes has not been clearly defined. Here we report a new family of patients with a typical HPX phenotype, linked to a novel GLRA1 mutation, inherited with a recessive pattern. We then perform a systematic review of the literature of GLRA1-related HPX, describing the main epidemiological features of 210 patients. We found that GLRA1-related phenotypes do not necessarily fulfill the current criteria for HPX, including also milder and later-onset phenotypes. Among clinical features of the disease, neurodevelopmental issues were reported in a third of the sample; interestingly, we found that these problems, particularly when severe, were more common in homozygous than in heterozygous patients. Additional clinical and preclinical studies are needed to define predictors of adverse neurodevelopmental outcomes and underlying mechanisms.

Electromyographic Patterns of Paratonia in Normal Subjects and in Patients with Mild Cognitive Impairment or Alzheimer's Disease.

BACKGROUND: Information on prevalence, pathophysiology, and clinical assessment of paratonia are scarce. In a previous study, we suggested that surface electromyography (EMG) can be used to assess paratonia. OBJECTIVE: To assess clinical and EMG features of paratonia in both patients with cognitive impairment and healthy subjects. METHODS: We examined 18 patients with Alzheimer's disease (AD), 21 patients with mild cognitive impairment (MCI), 30 healthy seniors (seniors), and 30 healthy juniors (juniors). Paratonia was assessed using the "Paratonia Scale". EMG bursts were recorded from biceps and triceps during manually applied passive movements of elbow joint. Continuous (sinusoidal) and discontinuous (linear) movements were applied at 2 different velocities (fast and slow). RESULTS: In comparison to juniors, seniors had higher clinical scores. In comparison to seniors, AD had higher oppositional scores, while MCI had higher facilitatory scores. EMG activity during passive movements correlated with paratonia clinical scores, was velocity-dependent and increased with movement repetition, most effectively for sinusoidal movements. Similar EMG activity was detected in not paratonic muscles. CONCLUSION: Paratonia increases with normal aging and cognitive decline progression. While facilitatory paratonia is due to involuntary contraction of the shortening muscle, oppositional paratonia is due, at least partially, to involuntary contraction of the lengthening muscle. Most characteristic feature of this muscle contraction is the progressive increase with movement repetition, that helps distinguish oppositional paratonia from spasticity and rigidity. A similar EMG activity is detected in not paratonic muscles, showing that, during tone assessment, the descending motor system is incompletely inactivated also in normotonic muscles.

Effects of fentanyl overdose-induced muscle rigidity and dexmedetomidine on respiratory mechanics and pulmonary gas exchange in sedated rats.

The objective of our study was to establish in sedated rats the consequences of high-dose fentanyl-induced acute muscle rigidity on the mechanical properties of the respiratory system and on the metabolic rate. Doses of fentanyl that we have previously shown to produce persistent rigidity of the muscles of the limbs and trunk in the rat (150-300 µg/kg iv), were administered in 23 volume-controlled mechanically ventilated and sedated rats. The effects of a low dose of the FDA-approved central α-2 agonist, dexmedetomidine (3 µg/kg iv), which has been suggested to oppose fentanyl-induced muscle rigidity, were determined after fentanyl administration. Fentanyl produced a significant decrease in compliance of the respiratory system (Crs) in all the rats that were studied. In 13 rats, an abrupt response occurred within 90 s, consisting of rapid rhythmic contractions of most skeletal muscles that were replaced by persistent tonic/tetanic contractions leading to a significant decrease of Crs (from 0.51 ± 0.11 mL/cmH2O to 0.36 ± 0.08 mL/cmH2O, 3 min after fentanyl injection). In the other 10 animals, Crs progressively decreased to 0.26 ± 0.06 mL/cmH2O at 30 min. There was a significant rise in oxygen consumption (V̇o2) during these muscle contractions (from 8.48 ± 4.31 to 11.29 ± 2.57 mL/min), which led to a significant hypoxemia, despite ventilation being held constant. Dexmedetomidine provoked a significant and rapid increase in Crs toward baseline levels, whereas decreasing the metabolic rate and restoring normoxemia. We propose that the changes in respiratory mechanics and metabolism produced by opioid-induced muscle rigidity contribute to fentanyl lethality.NEW & NOTEWORTHY The decrease in respiratory compliance and increased metabolism-induced hypoxemia produced by an overdose of fentanyl, in and of themselves, contribute to fentanyl toxicity.

A hacked kitchen scale-based system for quantification of grip strength in rodents.

BACKGROUND: Assessment of neuromuscular function is critical for understanding pathophysiological changes related to motor system dysfunction in many rodent disease models. Among methods used for quantification of grip performance in rodents, gauge-based grip strength meters provide the most reliable results, however, such instruments are unaffordable by many laboratories. The present aim was to demonstrate how to build a rodent grip strength apparatus from scratch using a digital kitchen scale, an empty cage, and a microcontroller, with both hardware and software being completely open-source to enable maximal modularity and flexibility of the instrument in concordance with the principles of open-source bioinstrumentation. METHODS: NodeMCU ESP-32S was connected to a hacked digital kitchen scale-based platform and load cell data were acquired using custom open-source scripts. Data were analyzed in R using semi-automatic analysis algorithms implemented in the ratPASTA package. griPASTA system was tested by quantifying muscular rigidity in the rat model of Parkinson's disease (PD) induced by bilateral intrastriatal administration of 6-hydroxydopamine (6-OHDA). RESULTS: In contrast to commercial instruments, the flexibility and modularity of the proposed platform enable collecting raw data and controlling for potential confounding effects on the grip strength. Muscular rigidity is significantly increased in the rat model of PD regardless of the dose used or reboxetine pretreatment. Neither trial speed nor animal weight was recognized as an important confounder. CONCLUSIONS: griPASTA provides a cheap, easy, precise, and reliable way to measure grip strength in rodents using widely available equipment and open-source software.

Antiparkinsonian activity of Tabebuia impetiginosa bark and biochemical analysis of dopamine in rat brain homogenates.

OBJECTIVES: Improving economy and well-being in developing nations like India has expanded life expectancy and changed the attention from transmittable to non transmittable diseases such as Parkinson's disease. Tabebuia impetiginosa has been utilized by cultivators as a general tonic, immunostimulant, adaptogen and also in motor disorders. The present investigation was to explore the antiparkinsonian activity of Tabebuia impetiginosa bark by experimental methods. MATERIALS AND METHODS: Control group-I was served with distilled water. Group-II was considered as pathological control [1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) 2mg/nostrils i.n, Reserpine 40mg/kg s.c, Haloperidol 0.5mg/kg, i.p]. Group-III served with standard drug (Apomorphine 40mg/kg, s.c). Group IV and V received aqueous extract of Tabebuia impetiginosa bark in doses of 300 and 500mg/kg/day respectively. Tremor, hypokinesia, muscular rigidity, catatonia, postural immobility, postural instability and catalepsy were assessed for antiparkinsonian activity. RESULTS: The bark extract served group exhibited the increased levels of dopamine (5700±1.84ng/g) when compared to control groups (4300±3.17ng/g). The extract at both the doses displayed a significant reduction in postural flexion, moderate decrease in tremor, muscular rigidity and postural immobility scores but do not exhibit significant lowering of hypokinesia score in reserpine induced Parkinsonian model. The reduction in catatonia and catalepsy scores is more remarkable in case of high dose of extract (500mg/kg) compared to standard drug in Neuroleptic induced Parkinsonism. CONCLUSION: The findings demonstrate that Tabebuia impetiginosa bark extract has significant anti-cataleptic potentials and the antioxidant effect of the bark may also be a significant contributor to its antiparkinsonian activity.

Flexibility and achilles tendon: a brief review / Flexibilidade e tendão de aquiles: uma breve revisão

Performing flexibility training in an exercise program is important to improve range of motion (ROM). Tendons have a profound impact on the general function of the musculoskeletal system, influence the limitation of ROM, and its structure and mechanical properties can benefit from stretching protocols. The systematic use of lower limbs in locomotion caused the Achilles tendon to become the largest and strongest tendon in the human body. Therefore, understanding the best prescription and frequency of flexibility exercise leads to changes in tendon properties is essential for an appropriate and effective exercise routine. Thus, the aim of this review was to organize and discuss publications about the implications of triceps surae stretching in ROM, as well as its influence on tendon properties. Acute studies show that continuous stretching times between five and 10 minutes cause decreased tendon stiffness, which is not seen in fractionated stretching times less than five minutes. Chronic studies, in turn, also don't present significant results in stiffness with fractionated times and studies with continuous times were not found. Thus, it is not possible to know if a continuous stretching time (longer than one minute) or a total time longer than five minutes but fractionated, can influence the tendon stiffness. (AU)

A realização de treino de flexibilidade como rotina em um programa de exercícios é importante para melhorar amplitude de movimento (ADM). Os tendões têm um impacto profundo na função geral do sistema musculoesquelético, influenciam na limitação da ADM, e sua estrutura e propriedades mecânicas podem se beneficiar de protocolos de alongamento. O uso sistemático dos membros inferiores na locomoção fez com que o tendão de Aquiles se tornasse o maior e mais forte tendão do corpo humano. Portanto, entender qual a melhor prescrição e frequência de exercício de flexibilidade para que ocasione alterações nas propriedades tendíneas é essencial para uma rotina de exercícios adequada e eficaz. Sendo assim, o objetivo dessa revisão de literatura foi organizar e discutir publicações sobre as implicações do alongamento do tríceps sural na ADM, bem como sua influência nas propriedades tendíneas. Estudos agudos mostram que tempos contínuos entre cinco e 10 minutos de alongamento estático causam diminuição da rigidez tendínea, o que não é visto em tempos intervalados inferiores a cinco minutos. Os estudos crônicos, por sua vez, também não apresentam resultados significativos na rigidez com protocolos de alongamento intervalados e estudos com protocolos contínuos não foram encontrados. Dessa forma, não é possível saber se um tempo contínuo de alongamento (superior a um minuto) ou um tempo superior a cinco minutos, intervalado, podem influenciar na rigidez tendínea. (AU)

Inspiratory laryngeal stridor as the main feature of progressive encephalomyelitis with rigidity and myoclonus: a case report and literature review.

BACKGROUND: Progressive encephalomyelitis with rigidity and myoclonus (PERM) is an acute, potentially life-threatening, yet curable neuro-immunological disease characterized by spasms, muscular rigidity, and brainstem and autonomic dysfunction. The clinical features of glycine receptor (GlyR) antibody-positive PERM may be overlooked, particularly with some unusual symptoms. CASE PRESENTATION: A 52-year-old man was admitted to the hospital for evaluation of tension headache for 20 days and mild dysarthria. These symptoms were followed by panic, profuse sweating, severe dysarthria, dizziness, unsteady gait, and paroxysmal muscle spasms. Brain magnetic resonance imaging and cerebrospinal fluid analysis were normal. The patient's condition steadily deteriorated. He repeatedly presented with rigidity, panic attacks, severe anxiety, paroxysmal inspiratory laryngeal stridor, cyanosis of the lips, and intractable epilepsy. Electromyography showed multiple myoclonic seizures, a single generalized tonic-clonic seizure, and a single generalized tonic seizure. Screening for autoimmune encephalitis antibodies revealed anti-GlyR antibodies in his cerebrospinal fluid. Immunomodulatory pulse therapy with steroids and immunoglobulin resulted in expeditious improvement of the symptoms within 2 weeks, and a follow-up at 5 weeks showed consistent clinical improvement. CONCLUSION: Our case highlights that inspiratory laryngeal stridor is an important symptom of PERM. Our observation widens the spectrum of the clinical presentation of anti-GlyR antibody-positive PERM, where early identification is a key to improving prognosis.

Gender differences in motor and non-motor symptoms in early Parkinson disease.

ABSTRACT: Gender differences in motor and non-motor symptoms in Parkinson disease (PD) are still controversial. This study aimed to investigate gender differences in clinical characteristics in patients with early PD.This study included 415 PD patients (201 men and 214 women) with modified Hoehn-Yahr stage 1 to 3 and a disease duration of ≤5 years. Demographic information was obtained by interviews, and motor and non-motor PD symptoms were evaluated with appropriate scales.Women with PD had a shorter duration of formal education than men with PD. No significant differences were found in other demographic variables. Women with PD had significantly lower scores in Unified Parkinson Disease Rating Scale part III and postural tremor compared to men with PD, which was significant after controlling for formal education. No significant gender-related differences were found in scores related to other motor symptoms. Concerning non-motor symptoms, men with PD had higher scores of sexual function on the Non-Motor Symptoms Scale, which means sexual dysfunction was more severe or occurred more frequently in men with PD. Women with PD had significantly higher scores of sleep disturbance in the Pittsburgh Sleep Quality Index, which was not significant after adjustment for multiple comparison.The present study suggests that women with PD had milder motor symptoms compared to men with PD, and gender differences in sexual function can be observed as non-motor symptoms.

Paratonía: un signo relevante en neuropsiquiatría / Paratonia: a relevant sign in neuropsychiatry

La paratonía es una alteración del tono motor, de interés en neuropsiquiatría por su presencia en la semiología de la demencia y la catatonía. En la paratonía, la resistencia a la manipulación pasiva es errática y depende de la intensidad del movimiento impuesto. Habitualmente se divide en un subtipo oposicionista (gegenhalten) y un subtipo facilitador (mitgehen). Desde el campo de las demencias, se han realizado esfuerzos para establecer una definición de consenso de la paratonía y para describir diferentes maniobras exploratorias, lo que contrasta con la indefinición y heterogeneidad conceptual que se encuentra en la literatura psiquiátrica alrededor de este término, que aún así, aparece en múltiples escalas y criterios diagnósticos de catatonía. Esto supone un problema en el contexto de las dificultades generales para definir y operacionalizar los signos característicos de la catatonía y la creación de instrumentos de evaluación aceptados universalmente. En el presente artículo se revisa la literatura científica de la paratonía con el objetivo de plasmar este problema, así como fomentar que los avances en su estudio desde otros campos puedan servir como referencia para su estudio en psiquiatría. (AU)

Paratonia is motor tone disturbance, of interest in neuropsychiatry due to its involvement in the semiology of dementia and catatonia. In paratonia, resistance to passive manipulation is erratic and depends on the intensity of the imposed movement. It is usually divided into an oppositional subtype (gegenhalten) and a facilitatory subtype (mitgehen). Efforts have been made in the field of dementia to establish a consensus definition of paratonia and to describe different exploratory manoeuvres. This contrasts with the conceptual ambiguity and heterogeneity found in the psychiatric literature regarding this term, which still appears in multiple scales and diagnostic criteria for catatonia. This is a problem given the general difficulties in defining and operationalising the characteristic signs of catatonia and in the creation of universally accepted assessment instruments. This article provides a review of scientific literature on paratonia to describe this problem, and encourage advances made in its research by other fields that could serve as a reference for its study in psychiatry. (AU)