Enhanced recovery and same-day discharge after brain tumor surgery under general anesthesia: initial experience with Hospital-at-Home-based postoperative follow-up.

OBJECTIVE: The objective of this study was to describe the outcomes of outpatient oncological neurosurgery (OON) in a European clinical setting and to compare them with the conventional inpatient protocol. METHODS: Patients who had undergone OON (either tumor removal or biopsy) at the authors' center since 2019 were analyzed. A matched cohort of patients was selected from patients undergoing tumor surgery in the same period. Collected data included patient demographics, postoperative progress, specific location of the target lesion, and the procedure performed. RESULTS: There were 18 patients in the case group and 59 patients in the control group. The outpatient surgeries had a same-day discharge rate of 89%, and all ambulatory patients successfully completed the Enhanced Recovery After Surgery program within 6.24 hours of the procedure. All ambulatory patients underwent Hospital-at-Home postoperative follow-up for an average of 4.12 days. Radiological complications were present in 11% of the case group and 8% of the control group. Postoperative neurological deficit occurred in 6% of the same-day discharge group and 3% of the control group. Among the patients in the control group, 3% suffered from postoperative seizures, whereas no seizures were observed in the case group. These differences were not statistically significant. General anesthesia-related complications were not observed in any of the patients. CONCLUSIONS: The authors' findings demonstrate that Enhanced Recovery After Surgery protocols and same-day discharge craniotomy for tumor resection and image-guided biopsy under general anesthesia, when patients are carefully selected, can be safely performed with excellent outcomes in a European clinical setting. The OON program proved to be a viable alternative to conventional hospitalization, showing comparable safety records and offering advantages in terms of patient recovery.

Discriminating Glioblastoma from Peritumoral Tissue by a Nanohole Array-Based Optical and Label-Free Biosensor.

In glioblastoma (GBM) patients, maximal safe resection remains a challenge today due to its invasiveness and diffuse parenchymal infiltration. In this context, plasmonic biosensors could potentially help to discriminate tumor tissue from peritumoral parenchyma based on differences in their optical properties. A nanostructured gold biosensor was used ex vivo to identify tumor tissue in a prospective series of 35 GBM patients who underwent surgical treatment. For each patient, two paired samples, tumor and peritumoral tissue, were extracted. Then, the imprint left by each sample on the surface of the biosensor was individually analyzed, obtaining the difference between their refractive indices. The tumor and non-tumor origins of each tissue were assessed by histopathological analysis. The refractive index (RI) values obtained by analyzing the imprint of the tissue were significantly lower (p = 0.0047) in the peritumoral samples (1.341, Interquartile Range (IQR) 1.339-1.349) compared with the tumor samples (1.350, IQR 1.344-1.363). The ROC (receiver operating characteristic) curve showed the capacity of the biosensor to discriminate between both tissues (area under the curve, 0.8779, p < 0.0001). The Youden index provided an optimal RI cut-off point of 0.003. The sensitivity and specificity of the biosensor were 81% and 80%, respectively. Overall, the plasmonic-based nanostructured biosensor is a label-free system with the potential to be used for real-time intraoperative discrimination between tumor and peritumoral tissue in patients with GBM.

Bispectral index monitoring to detect delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage.

PURPOSE: Evaluate the bispectral index (BIS) monitoring to detect delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage (aSAH). MATERIALS AND METHODS: A single-center prospective study in patients with aSAH. BIS monitoring was recorded during 25-120 min in two periods, within the initial 72 h (BIS1) and between days 4 and 6 (BIS2) from admission. The median for each exported BIS parameter was analyzed. Transcranial Doppler (TCD) sonography was simultaneously performed with BIS1 (TCD1) and BIS2 (TCD2) monitoring. A multivariate logistic regression model was built to identify the variables associated with DCI. RESULTS: Sixty-four patients were included and 16 (25%) developed DCI. During BIS2 monitoring, significant differences were found in BIS value (left, p = 0.01; right, p = 0.009), 95% spectral edge frequency (left and right, p = 0.04), and total power (left and right, p = 0.04). In multivariable analysis, vasospasm on TCD2 (OR 42.8 [95% CI 3.1-573]; p = 0.005), a median BIS2 value <85 in one or both sides (OR 6.2 [95% CI 1.28-30]; p = 0.023), and age (OR 1.08 [95% CI 1.00-1.17]; p = 0.04) were associated with the development of DCI. CONCLUSIONS: BIS value is the most useful BIS parameter for detecting DCI after aSAH. Pending further validation, BIS monitoring might be even more accurate than TCD.

Barriers and facilitators in the implementation of a telemedicine-based outpatient brain tumor surgery program.

OBJECTIVE: Despite growing evidence on the benefits of outpatient oncological neurosurgery (OON), it is only performed in a few specialized centers and there are no previous descriptions of established OON programs in Europe. Moreover, increasing application of telemedicine strategies, especially after the start of the coronavirus disease 2019 (COVID-19) pandemic, is drastically changing neurosurgical management, particularly in the case of vulnerable populations such as neuro-oncological patients. In this context, the authors implemented an OON program in their hospital with telematic follow-up. Herein, they describe the protocol and qualitatively analyze the barriers and facilitators of the development process. METHODS: An OON program was developed through the following steps: assessment of hospital needs, specific OON training, multidisciplinary team organization, and OON protocol design. In addition, the implementation phase included training sessions, a pilot study, and continuous improvement sessions. Finally, barriers and facilitators of the protocol's implementation were identified from the feedback of all participants. RESULTS: An OON protocol was successfully designed and implemented for resection or biopsy of supratentorial lesions up to 3 cm in diameter. The protocol included the patient's admission to the day surgery unit, noninvasive anesthetic monitoring, same-day discharge, and admission to the hospital-at-home (HaH) unit for telematic and on-site postoperative care. After a pilot study including 10 procedures in 9 patients, the main barriers identified were healthcare provider resistance to change, lack of experience in outpatient neurosurgery, patient reluctance, and limitations in the recruitment of patients. Key facilitators of the process were the patient education program, the multidisciplinary team approach, and the HaH-based telematic postoperative care. CONCLUSIONS: Initiating an OON program with telematic follow-up in a European clinical setting is feasible. Nevertheless, it poses several barriers that can be overcome by identifying and maximizing key facilitators of the process. Among them, patient education, a multidisciplinary team approach, and HaH-based postoperative care were crucial to the success of the program. Future studies should investigate the cost-effectiveness of telemedicine to assess potential cost savings, from reduced travel and wait times, and the impact on patient satisfaction.

Cirugía endoscópica endonasal durante la pandemia COVID-19: protocolo de actuación / Endoscopic endonasal surgery during COVID-19 pandemic: Management guideline

La actual pandemia por coronavirus SARS-CoV-2 está planteando una serie de desafíos al modo en que ejercemos la actividad médica y quirúrgica. En concreto, dentro de la neurocirugía se ha visto que los abordajes endoscópicos endonasales suponen un elevado riesgo de contagio para el personal sanitario que interviene en la misma, por lo que, inicialmente, la recomendación fue evitar dichas cirugías. Dado que la pandemia se ha extendido en el tiempo y desconocemos cuándo se podrá controlar, se deben proponer nuevas soluciones para continuar con la realización de dichos abordajes de manera segura. Ante la falta de protocolos establecidos, planteamos el siguiente, en el que se establecen, de modo conciso, las medidas a tomar tanto en cirugía urgente como programada, además de la descripción de un nuevo dispositivo de protección-aspirado (Maskpirator) AU)

Current SARS-CoV-2 coronavirus pandemic is challenging medical and surgical activities. Specifically, within neurosurgery, endoscopic endonasal approaches pose a high risk of contagion for healthcare personnel involved in it. Initially, the recommendation was to avoid such surgeries. However, the pandemic has dragged on and new solutions must be proposed to continue carrying out these approaches safely. Given the lack of established protocols, we propose the following one, which concisely establishes the measures to be taken in both urgent and scheduled surgery. In addition, a new protecti (AU)n-aspiration device (Maskpirator) is described.

A rare case of a secondary pituitary abscess arising in a craniopharyngioma with atypical presentation and clinical course.

Pituitary abscesses are very uncommon. They are divided into primary, arising within a healthy gland, and secondary, observed with an underlying pre-existing lesion. Here we present the eighth case reported of a secondary abscess within a craniopharyngioma. A 59-year-old-woman presented with a 3-week history of headache, and fever. Physical examination was unremarkable. An Magnetic Resonance Imaging (MRI) showed a pituitary lesion suggestive of a chronic inflammatory process. She was diagnosed with lymphocytic meningitis with hypophysitis and she was treated with corticosteroids. Two months later she presented with headache and fever again. Control MRI showed enlargement of the pituitary lesion. Therefore, a transsphenoidal biopsy was performed. During the procedure, purulent material was released. Histological study demonstrated a craniopharyngioma and meningeal inflammation. Empiric antibiotics were started. Three months post-operatively, a follow-up MRI showed a suspect minimal residual mass. Secondary pituitary abscesses are rare. The key to successful management is a high index of suspicion. Transsphenoidal surgical evacuation plus antibiotics is the mainstay of treatment. Although most symptoms resolve, endocrinopathies improve only rarely.

[Endoscopic endonasal surgery during COVID-19 pandemic: Management guideline]. / Cirugía endoscópica endonasal durante la pandemia COVID-19: protocolo de actuación.

Current SARS-CoV-2 coronavirus pandemic is challenging medical and surgical activities. Specifically, within neurosurgery, endoscopic endonasal approaches pose a high risk of contagion for healthcare personnel involved in it. Initially, the recommendation was to avoid such surgeries. However, the pandemic has dragged on and new solutions must be proposed to continue carrying out these approaches safely. Given the lack of established protocols, we propose the following one, which concisely establishes the measures to be taken in both urgent and scheduled surgery. In addition, a new protection-aspiration device (Maskpirator) is described.

Endoscopic endonasal surgery during COVID-19 pandemic: Management guideline.

Current SARS-CoV-2 coronavirus pandemic is challenging medical and surgical activities. Specifically, within neurosurgery, endoscopic endonasal approaches pose a high risk of contagion for healthcare personnel involved in it. Initially, the recommendation was to avoid such surgeries. However, the pandemic has dragged on and new solutions must be proposed to continue carrying out these approaches safely. Given the lack of established protocols, we propose the following one, which concisely establishes the measures to be taken in both urgent and scheduled surgery. In addition, a new protection-aspiration device (Maskpirator) is described.

Intracortical focal non-convulsive status epilepticus causing cerebral hypoxia and intracranial hypertension.

We describe the pathophysiological consequences and long-term neurological outcome of a patient with acute brain injury (ABI) in whom intracortical electroencephalography (iEEG) captured an episode of prolonged focal non-convulsive status epilepticus (NCSE) that remained undetectable on scalp electroencephalography. A 53-year-old right-handed woman was admitted to hospital due to a large frontal left intraparenchymal hematoma. Over two and a half days, we captured recurrent non-convulsive electrographic and electroclinical seizures compatible with the diagnosis of intracortical focal NCSE. The patient remained sedated and a burst-suppression pattern was obtained. We also performed invasive brain multimodality monitoring including iEEG and measurements of intracranial pressure (ICP), partial brain tissue oxygenation (PbtO2) and brain temperature. During non-convulsive electrographic and electroclinical seizures, the values of PbtO2 decreased and those of ICP increased. Six months later, brain MRI revealed encephalomalacia localized to the left paramedial fronto-basal region. The neuropsychological assessment carried out one year after the injury showed scores below average in verbal learning memory, motor dexterity and executive functions. In summary, iEEG is a feasible innovative invasive technique that may be used to record non-convulsive electrographic and electroclinical seizures which remain invisible on the surface. Intracortical focal NCSE causes metabolic changes such as reduced brain oxygenation and an increase in ICP that can further damage previously compromised brain tissue.

A rare case of a secondary pituitary abscess arising in a craniopharyngioma with atypical presentation and clinical course.

Pituitary abscesses are very uncommon. They are divided into primary, arising within a healthy gland, and secondary, observed with an underlying pre-existing lesion. Here we present the eighth case reported of a secondary abscess within a craniopharyngioma. A 59-year-old-woman presented with a 3-week history of headache, and fever. Physical examination was unremarkable. An Magnetic Resonance Imaging (MRI) showed a pituitary lesion suggestive of a chronic inflammatory process. She was diagnosed with lymphocytic meningitis with hypophysitis and she was treated with corticosteroids. Two months later she presented with headache and fever again. Control MRI showed enlargement of the pituitary lesion. Therefore, a transsphenoidal biopsy was performed. During the procedure, purulent material was released. Histological study demonstrated a craniopharyngioma and meningeal inflammation. Empiric antibiotics were started. Three months post-operatively, a follow-up MRI showed a suspect minimal residual mass. Secondary pituitary abscesses are rare. The key to successful management is a high index of suspicion. Transsphenoidal surgical evacuation plus antibiotics is the mainstay of treatment. Although most symptoms resolve, endocrinopathies improve only rarely.

Variability of Clinical and Angiographic Results Based on the Treatment Preference (Endovascular or Surgical) of Centers Participating in the Subarachnoid Hemorrhage Database of the Working Group of the Spanish Society of Neurosurgery.

OBJECTIVES: Since the introduction of endovascular treatment for cerebral aneurysms, hospitals in which subarachnoid hemorrhage is treated show different availability and/or preferences towards both treatment modalities. The main aim is to evaluate the clinical and angiographic results according to the hospital's treatment preferences applied. METHODS: This study was conducted based on use of the subarachnoid hemorrhage database of the Vascular Pathology Group of the Spanish Neurosurgery Society. Centers were classified into 3 subtypes according to an index in the relationship between endovascular and surgical treatment as: endovascular preference, high endovascular preference, and elevated surgical preference. The clinical results and angiographic results were evaluated among the 3 treatment strategies. RESULTS: From November 2004 to December 2017, 4282 subarachnoid hemorrhage patients were selected for the study: 630 (14.7%) patients from centers with surgical preference, 2766 (64.6%) from centers with endovascular preference, and 886 (20.7%) from centers with high endovascular preference. The surgical preference group obtained the best angiographic results associated with a greater complete exclusion (odds ratio: 1.359; 95% confidence interval: 1.025-1.801; P = 0.033). The surgical preference subgroup obtained the best outcome at discharge (65.45%), followed by the high endovascular preference group (61.5%) and the endovascular preference group (57.8%) (odds ratio: 1.359; 95% confidence interval: 1.025-1.801; P = 0.033). CONCLUSIONS: In Spain, there is significant variability in aneurysm exclusion treatment in aneurysmal subarachnoid hemorrhage. Surgical centers offer better results for both surgical and endovascular patients. A multidisciplinary approach and the maintenance of an elevated quality of surgical competence could be responsible for these results.

Protocolo de consenso en el tratamiento antitrombótico (anticoagulación y antiagregación) durante el periodo perioperatorio y periprocedimiento en neurocirugía / Antithrombotic treatment consensus protocol (anticoagulation and antiplatelet therapy) during the perioperative and periprocedural period in neurosurgery

El uso de medicación antitrombótica (antiagregante y/o anticoagulante) se encuentra ampliamente extendido. El manejo de los pacientes neuroquirúrgicos que reciben este tipo de terapia continúa siendo, a día de hoy, un problema de especial importancia. Los pacientes en tratamiento antitrombótico pueden necesitar atención neuroquirúrgica bien por presentar sangrados secundarios a dicho tratamiento, lesiones neuroquirúrgicas no hemorrágicas pero que precisen intervención urgente, o simplemente procedimientos neuroquirúrgicos electivos. Además, las consecuencias de la reintroducción de la anticoagulación temprana (sangrado o resangrado) o tardía (trombóticas o tromboembólicas) pueden ser devastadoras. En este documento presentamos el protocolo de consenso en el tratamiento antitrombótico durante el periodo perioperatorio y periprocedimiento, tanto en cirugía emergente como en procedimientos electivos de neurocirugía

The use of antithrombotic medication (antiplatelet and/or anticoagulant therapy) is widespread. Currently, the management of neurosurgical patients receiving this type of therapy continues to be a problem of special importance. Patients receiving antithrombotic treatment may need neurosurgical care because of bleeding secondary to such treatment, non-haemorrhagic neurosurgical lesions requiring urgent attention, or simply elective neurosurgical procedures. In addition, the consequences of reintroducing early (bleeding or rebleeding) or late (thrombotic or thromboembolic) anticoagulation can be devastating. In this paper we present the antithrombotic treatment consensus protocol during the perioperative and periprocedural period, both in emergent surgery and in elective neurosurgical procedures

[Antithrombotic treatment consensus protocol (anticoagulation and antiplatelet therapy) during the perioperative and periprocedural period in neurosurgery]. / Protocolo de consenso en el tratamiento antitrombótico (anticoagulación y antiagregación) durante el periodo perioperatorio y periprocedimiento en neurocirugía.

The use of antithrombotic medication (antiplatelet and/or anticoagulant therapy) is widespread. Currently, the management of neurosurgical patients receiving this type of therapy continues to be a problem of special importance. Patients receiving antithrombotic treatment may need neurosurgical care because of bleeding secondary to such treatment, non-haemorrhagic neurosurgical lesions requiring urgent attention, or simply elective neurosurgical procedures. In addition, the consequences of reintroducing early (bleeding or rebleeding) or late (thrombotic or thromboembolic) anticoagulation can be devastating. In this paper we present the antithrombotic treatment consensus protocol during the perioperative and periprocedural period, both in emergent surgery and in elective neurosurgical procedures.

Pronóstico a largo plazo de la hidrocefalia crónica del adulto idiopática: I. Protocolo diagnóstico-terapéutico del Hospital Universitario Marqués de Valdecilla / Long-term prognosis of idiopathic chronic adult hydrocephalus: I. The University Hospital Marqués de Valdecilla diagnostic and therapeutic protocol

Introducción: A pesar de la existencia de guías clínicas desde hace más de una década, la complejidad diagnóstica y terapéutica de la hidrocefalia crónica del adulto idiopática hace que la variabilidad en su manejo sea elevada. Desarrollo: Se presenta el protocolo diagnóstico-terapéutico empleado en el Servicio de Neurocirugía del Hospital Universitario Marqués de Valdecilla para evaluar a los pacientes remitidos por sospecha diagnóstica de hidrocefalia crónica del adulto idiopática. El proceso diagnóstico incluye valoración neuropsicológica, RM craneal con secuencias de Cine-RM por contraste de fase, estudio urodinámico, registro continuo de presión intracraneal, hidrodinámica licuoral mediante test de infusión lumbar y medición de la presión intraabdominal. Se consideran candidatos quirúrgicos a los pacientes que cumplen cualquiera de los siguientes criterios: presión intracraneal media > 15 mmHg u ondas B en > 10% del registro nocturno; índice presión-volumen < 15 ml o resistencia al drenaje del líquido cefalorraquídeo (ROUT) > 4,5 mmHg/ml/min en el test de bolos; ROUT > 12 mmHg/ml/min, presión intracraneal > 22 mmHg o presencia de ondas B de alta amplitud en la meseta del test de Katzman; o respuesta a la evacuación licuoral de alto volumen. Conclusiones: La implementación de protocolos diagnóstico-terapéuticos podría mejorar varios aspectos del proceso asistencial de la hidrocefalia crónica del adulto idiopática, no solo al disminuir la variabilidad en la práctica clínica sino también al optimizar el uso de recursos sanitarios y ayudar a la identificación de áreas de incertidumbre científica, permitiendo dirigir los esfuerzos en investigación de una forma más adecuada

Introduction: Despite the existence of published guidelines for more than a decade, there is still a substantial variation in the management of idiopathic normal pressure hydrocephalus due to its diagnostic and therapeutic complexity. Development: The diagnostic and therapeutic protocol for the management of idiopathic normal pressure hydrocephalus in use at the Department of Neurosurgery of the University Hospital Marqués de Valdecilla is presented. The diagnostic process includes neuropsychological testing, phase contrast cine MRI, urodynamic evaluation, continuous intracranial pressure monitoring, cerebrospinal fluid hydrodynamics by means of lumbar infusion testing, and intra-abdominal pressure measurement. A patient is considered a surgical candidate if any of the following criteria is met: mean intracranial pressure > 15 mmHg, or B-waves present in >10% of overnight recording; pressure-volume index < 15 ml, or resistance to cerebrospinal fluid outflow (ROUT) > 4.5 mmHg/ml/min in bolus infusion test; ROUT >12 mmHg/ml/min, intracranial pressure > 22 mmHg, or high amplitude B-waves in the steady-state of the continuous rate infusion test; or a clinical response to high-volume cerebrospinal fluid withdrawal. Conclusions: The implementation of a diagnostic and therapeutic protocol for idiopathic normal pressure hydrocephalus management could improve various aspects of patient care. It could reduce variability in clinical practice, optimise the use of health resources, and help in identifying scientific uncertainty areas, in order to direct research efforts in a more appropriate way

[Long-term prognosis of idiopathic chronic adult hydrocephalus: I. The University Hospital Marqués de Valdecilla diagnostic and therapeutic protocol]. / Pronóstico a largo plazo de la hidrocefalia crónica del adulto idiopática: I. Protocolo diagnóstico-terapéutico del Hospital Universitario Marqués de Valdecilla.

INTRODUCTION: Despite the existence of published guidelines for more than a decade, there is still a substantial variation in the management of idiopathic normal pressure hydrocephalus due to its diagnostic and therapeutic complexity. DEVELOPMENT: The diagnostic and therapeutic protocol for the management of idiopathic normal pressure hydrocephalus in use at the Department of Neurosurgery of the University Hospital Marqués de Valdecilla is presented. The diagnostic process includes neuropsychological testing, phase contrast cine MRI, urodynamic evaluation, continuous intracranial pressure monitoring, cerebrospinal fluid hydrodynamics by means of lumbar infusion testing, and intra-abdominal pressure measurement. A patient is considered a surgical candidate if any of the following criteria is met: mean intracranial pressure >15mmHg, or B-waves present in >10% of overnight recording; pressure-volume index <15ml, or resistance to cerebrospinal fluid outflow (ROUT) >4.5mmHg/ml/min in bolus infusion test; ROUT >12mmHg/ml/min, intracranial pressure >22mmHg, or high amplitude B-waves in the steady-state of the continuous rate infusion test; or a clinical response to high-volume cerebrospinal fluid withdrawal. CONCLUSIONS: The implementation of a diagnostic and therapeutic protocol for idiopathic normal pressure hydrocephalus management could improve various aspects of patient care. It could reduce variability in clinical practice, optimise the use of health resources, and help in identifying scientific uncertainty areas, in order to direct research efforts in a more appropriate way.

Incidence of Idiopathic Normal-Pressure Hydrocephalus in Northern Spain.

BACKGROUND: Although the incidence of idiopathic normal-pressure hydrocephalus (iNPH) can be 1.20 cases/1000 inhabitants/year in individuals ≥ 70 years old, in most series, the incidence of shunt-responsive iNPH appears to be <1/100,000 inhabitants/year. We report the results of a prospective 10-year longitudinal study of the incidence of iNPH in a northern Spanish population. METHODS: In a stable population of 590,000 inhabitants served by a single neurosurgical department, we periodically asked all primary care practitioners, neurologists, and geriatricians to refer for iNPH screening any patient with ventricular dilation who was complaining of motor disturbances, cognitive impairment, or sphincter dysfunction. RESULTS: From January 2003 to December 2012, 293 patients were referred with suspected normal-pressure hydrocephalus. In 187 patients, iNPH was diagnosed; 89 of these patients were classified as probable iNPH, and 98 were classified as possible iNPH. Cerebrospinal fluid diversion was performed in 152 patients, and 119 showed a good outcome. The incidence of iNPH was significantly greater in male patients and patients >60 years old and increased exponentially with age. After age 60, the standardized age- and sex-adjusted incidence rates for iNPH, shunt surgery for iNPH, and shunt-responsive iNPH were 13.36 cases/100,000 inhabitants/year, 10.85 cases/100,000 inhabitants/year, and 8.55 cases/100,000 inhabitants/year. No differences were detected in the response rate between probable and possible iNPH (80.52% vs. 76.00%; P = 0.497). CONCLUSIONS: Even with a protocol for patient referral in place, reported iNPH incidence was lower than predicted, reflecting a persistent problem of underdiagnosis in our population.

Epidemiology of Idiopathic Normal Pressure Hydrocephalus: A Systematic Review of the Literature.

BACKGROUND: Idiopathic normal pressure hydrocephalus (iNPH) is an important cause of gait disturbance and cognitive impairment in elderly adults. However, the epidemiology of iNPH is relatively unknown, largely as a result of the paucity of specifically designed population studies. This systematic review aims to assess the prevalence and incidence of iNPH. METHODS: A systematic literature review on the epidemiology of iNPH was conducted using MEDLINE/PubMed searching for articles published up to June 2014. RESULTS: The inclusion criteria were met by 21 studies. Of the studies, 12 were specifically designed for detecting cases of iNPH; however, only 4 were prospective. In people >65 years old, pooled prevalence obtained from specific population studies was 1.3%, which was almost 50-fold higher than that inferred from door-to-door surveys of dementia or parkinsonism. Prevalence may be higher in assisted-living and extended-care residents, with 11.6% of patients fulfilling the criteria for suspected iNPH and 2.0% of patients showing permanent improvement after cerebrospinal fluid diversion. The only prospective population-based survey that reported iNPH incidence estimated 1.20 cases/1000 inhabitants/year, 15-fold higher than estimates obtained from studies based on hospital catchment areas. The incidence of shunt surgery for iNPH and shunt-responsive iNPH obtained from incident cases of hospital catchment areas appears to be <2 cases/100,000 inhabitants/year and 1 case/100,000 inhabitants/year, respectively. No population-based study reporting the real values for these 2 parameters could be found. CONCLUSIONS: iNPH appears to be extremely underdiagnosed. Properly designed and adequately powered population-based studies are required to characterize the epidemiology of this disease accurately.