Overview of Idiopathic Normal Pressure Hydrocephalus: Diagnosis and Improvement

Idiopathic normal pressure hydrocephalus (iNPH) is an uncommon yet potentially reversible cause of dementia in the elderly. It is characterized by cognitive deterioration, urinary incontinence, ventriculomegaly (enlarged cerebral ventricles) and gait apraxia. The diagnosis and management of iNPH requires an organized approach, starting with a comprehensive history and neurologic examination, a review of neuroimaging, and an evaluation of diagnosis. It is important to treat comorbidities in patients prior to specific iNPH testing, which includes testing patient responses to temporary CSF removal and assessing CSF hydrodynamics. In carefully selected patients, all physiological and neurological symptoms improved with a ventriculoperitoneal (VP) shunt surgery, which allows for a gradual adjustment in pressure to prevent complications caused by over-drainage.

Ultrasonography for Serial Monitoring and Management of CSF Dynamic Disorders After Decompressive Craniectomy

Objective Decompressive craniectomy (DC) is widely used to treat intracranial hypertension following severe head injury. However, impairments of cerebrospinal fluid (CSF) hydrodynamics such as hydrocephalus and subdural effusion are common complications that occur after DC. Therefore, monitoring of intracranial pressure is a staple of neurocritical care post-DC. The aim of this study was to assess the usefulness of transcranial duplex sonography (TDS) for serial monitoring and management of CSF disorders after DC. Methods A total of 100 patients who underwent DC between June 2016 and May 2019 were recruited for the study. TDS examinations were performed between 1 day and 1-year post-DC. TDS was mainly used for monitoring changes in ventricle size and morphology, and also to monitor intraventricular hemorrhage (IVH), hydrocephalus, intracranial hygromas, and ventricle changes during CSF release procedures. Results A total of 456 TDS examinations were performed on patients after DC. Of these, 402 were performed in the neuro-ICU. Two patients had IVH and underwent TDS-guided external ventricular drainage (EVD). Twenty-nine patients were diagnosed with hydrocephalus. The results of TDS were consistent with those of cranial computed tomography (CCT). Three cases of ventriculoperitoneal shunt and 1 case of lumbar peritoneal shunt underwent valve pressure reset according to TDS, in order to obtain satisfactory ventricle size. TDS was used to monitor ventricle changes and control drainage volume during CSF release procedures, including 2 EVD, 6 external lumbar drainage, and 10 lumbar punctures. Eighteen patients were detected with single or multiple intracranial effusions, including 16 subdural hygromas, 5 longitudinal fissure hygromas, and 6 brain cysts. Conclusions TDS can efficiently help monitor changes in ventricle size and morphology and intracranial effusions. Due to its noninvasive nature, suitability for bedside application, real-time and inexpensiveness, TDS can significantly replace CCT and become part of the patient's daily inspection work after DC.

Cerebrospinal fluid hydrodynamics in arachnoid cyst patients with persistent idiopathic intracranial hypertension: A case series and review

Background: A clear connection has been established between arachnoid cysts (ACs) and the evolution of idiopathic intracranial hypertension (IIH), a connection, which is presently not well understood. Cerebrospinal fluid (CSF) is an integral element of this condition. Little is known about either the influence of AC on CSF hydrodynamics or the specific nature of CSF, which contributes to the complex pathology of IIH. Case Description: This study aimed to chronicle in detail four patients with previously treated intracranial ACs, who developed persistent IIH. This series and review aims to identify and qualitatively analyze the multiple constituents, which could possibly elucidate the intrinsic relationship between arachnoid cyst-induced IIH and CSF hydrodynamics. A retrospective analysis of the medical records of four patients admitted to the institution’s neurosurgery department during the period of 1994–2013 was completed. This study investigated discernible aspects linking CSF pathophysiology with the development of IIH in AC patients. Four male patients, ranging from 3 to 44 years of age at presentation, had a left-sided arachnoid cyst treated surgically. All four patients subsequently developed IIH. Three patients remain persistently symptomatic. Conclusion: IIH associated with AC is a hydrodynamic disorder. The full discovery of its fluctuant pathophysiology is the only way to identify an effective standard for the management and treatment of this condition.

Spinal cerebrospinal fluid dynamics

Cerebrospinal fluid (CSF) within the spinal canal is far from a stagnant column of liquid, simply bathing the spinal cord, but is constantly being subjected to waves of energy, produced by both the cardiac and the respiratory cycles. Moreover, the spinal subarachnoid channels are normally in free communication with the intracranial basal cisterns and volume exchanges take place between these two compartments, during normal daily activities. A variety of pathological processes can alter CSF hydrodynamics, leading to the development of several conditions. These include Chiari malformations and syringomyelia, as well as extra-axial collections of CSF. They are best regarded as disorders of CSF circulation, rather than as isolated spinal pathologies.

Selection of patients with idiopathic normal-pressure hydrocephalus for shunt placement: a single-institution experience

Object The ability to predict outcome after shunt placement in patients with idiopathic normal-pressure hydrocephalus (NPH) represents a challenge. To date, no single diagnostic tool or combination of tools has proved capable of reliably predicting whether the condition of a patient with suspected NPH will improve after a shunting procedure. In this paper, the authors report their experience with 120 patients with the goal of identifying CSF hydrodynamics criteria capable of selecting patients with idiopathic NPH. Specifically, they focused on the comparison between CSF-outflow resistance (R-out) and intracranial elastance (IE). Methods Between January 1977 and December 2005, 120 patients in whom idiopathic NPH had been diagnosed (on the basis of clinical findings and imaging) underwent CSF hydrodynamics evaluation based on an intraventricular infusion test. Ninety-six patients underwent CSF shunt placement: 32 between 1977 and 1989 (Group I) on the basis of purely clinical and radiological criteria; 44 between 1990 and 2002 (Group II) on the basis of the same criteria as Group I and because they had an IE slope > 0.25; and 20 between 2003 and 2005 (Group III) on the basis of the same criteria as Group II but with an IE slope ≥ 0.30. Outcomes were evaluated by means of both Stein-Langfitt and Larsson scores. Patients' conditions were considered improved when there was a stable decrease (at 6- and 12-month follow-up) of at least 1 point in the Stein-Langfitt score and 2 points in the Larsson score. Results Group I: while no statistically significant difference in mean R-out value between improved and unimproved cases was observed, a clear-cut IE slope value of 0.25 differentiated very sharply between unimproved and improved cases. Group II: R-out values in the 2 unimproved cases were 20 and 47 mm Hg/ml/min, respectively. The mean IE slope in the improved cases was 0.56 (range 0.30–1.4), while the IE slopes in the 2 unimproved cases were 0.26 and 0.27. Group III: the mean IE slope was 0.51 (range 0.31–0.7). The conditions of all patients improved after shunting. A significant reduction of the Evans ratio was observed in 34 (40.5%) of the 84 improved cases and in none of the unimproved cases. Conclusions Our strategy based on the analysis of CSF pulse pressure parameters seems to have a great accuracy in predicting surgical outcome in clinical practice.

Hydrocephalus and craniosynostosis

Object. A retrospective study of 1727 cases of craniosynostosis was undertaken to determine the interrelationship between abnormal cerebrospinal fluid (CSF) hydrodynamics and craniosynostosis. Methods. The patients were divided into two groups: nonsyndromic craniosynostosis and syndromic craniosynostosis. Cases of occipital plagiocephaly without suture synostosis and cases of shunt-induced craniosynostosis were excluded from the study. The majority of patients (1297) were treated surgically for their cranial deformity; 95% of these patients had a postoperative follow-up review period lasting 5 years. Clinical and radiographic charts covering the time from presentation through the follow-up period were reviewed. Conclusions. Abnormal intracranial CSF hydrodynamics was found in 8.1% of the patients (3.4% of whom had received shunts and 4.5% of whom had not). Three types of CSF hydrodynamic disturbance were observed: progressive hydrocephalus with ventricular dilation, nonprogressive ventriculomegaly, and dilation of the subarachnoid spaces. Hydrocephalus occurred much more frequently in patients with syndromic craniosynostosis (12.1%) than in those with isolated craniosynostosis (0.3%). In fact, patients with kleeblattschädel exhibited hydrocephalus as a constant feature and patients with Crouzon's syndrome were far more likely to have hydrocephalus than those with other syndromes. In Apert's syndrome, ventricular dilation occurred very frequently, but it was almost always nonprogressive in nature. In most cases of syndromic craniosynostosis, venous sinus obstruction and/or chronic tonsillar herniation were found. Their role in the pathophysiology of hydrocephalus in craniosynostosis is discussed.