Adult Hydrocephalus

Description

Adult hydrocephalus is an insidious yet treatable condition that develops slowly, with usual onset around 60 years of age. It is poorly recognized and many cases are not diagnosed until late in the course of disease, leading to poorer patient outcomes and a high financial cost to healthcare providers. The resulting neurological symptoms include gait/balance problems, loss of bladder control, and a cognitive decline leading to dementia, which is often mistaken for Alzheimer's disease. This book - the first published on this topic since 1993 - provides comprehensive guidelines to improve the speed and accuracy of diagnosis, and covers various neurosurgical techniques used to treat the disease, including the insertion of different types of shunts and endoscopic third ventriculostomy. This is essential reading for neurologists, neurosurgeons, family physicians, and radiologists who may well encounter adult patients with hydrocephalus more often than they realize. Front Matter Copyright Dedication Contents Contributors Prologue Section 1 Basic sciences 1 Anatomy and physiology of the cerebrospinal fluid system Introduction Water distribution of the brain CSF function CSF composition Anatomy of the CSF system Anatomy of the lateral ventricles Anatomy of the foramina of Monro Anatomy of the third ventricle Cerebral aqueduct Anatomy of the fourth ventricle Overview of the cisterns Cerebral convexity CSF spaces Spinal CSF anatomy CSF production Choroid plexus Structure CSF secretion Other functions Interstitial fluid contribution to CSF production CSF flow Cellular composition of the ventricles CSF flow through the ventricles CSF flow through the cranial subarachnoid cisterns and Virchow–Robin spaces CSF flow through the spinal central canal and subarachnoid space Other possible routes of CSF circulation CSF absorption Arachnoid granulations Lymphatic drainage Windkessel effect on CSF drainage Conclusion 2 Neuropathology of human hydrocephalus Introduction Factors leading to ventricular enlargement Consequences of ventricular enlargement and pathogenesis of brain damage in hydrocephalus NPH and white matter and cerebrovascular disease Hydrocephalus and the extracellular fluid NPH and Alzheimer’s disease NPH and autopsy findings Secondary reactive changes due to hydrocephalus Altered neurons and connections in the hydrocephalic brain Summary Conflict of interest disclaimer Funding support 3 Animal models of hydrocephalus Ethics of animal models Formal requirements – general to any experimental model Requirements and challenges for models of hydrocephalus Existing and preferred models Hydrocephalus induced by physical or chemical agents Genetically determined hydrocephalus in inbred strains or by genetic manipulation Recent and current research areas in experimental hydrocephalus Normal pressure hydrocephalus (NPH) 4 Genetics of hydrocephalus Introduction Genetic epidemiology Twin studies Epidemiology Genetics in hydrocephalus Human hydrocephalus Idiopathic normal pressure hydrocephalus Congenital hydrocephalus Animal hydrocephalic models Quantitative trait locus (QTL) Monogenic congenital hydrocephalus Genetic basis for pathophysiology of hydrocephalus Loss of the key molecular cues during early development Subcommissural organ (SCO) defects Ciliopathies Deficient water channels Disrupted apoptotic pathways Neural tube defects Altered immune response Unknown causes Enhanced expression during early development Conclusion 5 The epidemiology of hydrocephalus Introduction Epidemiology of specific types of hydrocephalus Congenital and infantile hydrocephalus Idiopathic normal pressure hydrocephalus (iNPH) Secondary normal pressure hydrocephalus The frequency of surgery for iNPH and sNPH Section 2 Pathophysiology 6 Pathophysiology of gait dysfunction in normal pressure hydrocephalus Introduction Objective measures of gait dysfunction in NPH Tentative theories to explain gait dysfunction in NPH Midbrain atrophy or compression Cortical dysfunction Cortical-subcortical and intracortical circuit abnormalities Postural dysfunction Dopamine signaling abnormalities Decreased regional cerebral blood flow Conclusion 7 The pathophysiologic basis of cognitive dysfunction in idiopathic normal pressure hydrocephalus Introduction Putative pathogenic mechanisms of iNPH General features of cognitive impairment in iNPH Neuropsychological evaluation in iNPH Localization of neuropsychological deficits in iNPH Attention/Executive/Psychomotor Memory Visuospatial Motor skills Response to CSF drainage (tap test, external lumbar drainage, shunt) Differential diagnosis/comorbidities Differential diagnostic considerations Conclusions 8 Incontinence and lower urinary tract symptoms in normal pressure hydrocephalus Introduction Dementia and incontinence Differential diagnosis Pathophysiology of incontinence in NPH Normal micturitional physiology Pathophysiology of incontinence and lower urinary tract symptoms in NPH Evaluation of urinary symptoms in NPH patients Terminology Urologic history Validated questionnaires Physical examination Diagnostic testing Urodynamic testing Characterization of lower urinary tract symptoms in NPH The Virginia Commonwealth University experience Treatment of NPH-mediated incontinence Short-term results for incontinence after shunt surgery Long-term results for incontinence after shunt surgery Conclusions Dedication 9 Normal pressure hydrocephalus grading scales Introduction Scales General activity NPH symptomatology assessment Qualitative assessment Quantitative or semiquantitative assessment Combination of qualitative and quantitative assessment Comorbidity Caregiver burden scale Comparison between scales Conclusion Section 3 Diagnosis 10 The differential diagnosis of normal pressure hydrocephalus Introduction The neurological examination of the NPH patient The diagnostic work-up of the NPH patient Gait dysfunction Cognitive deficit Urinary dysfunction Imaging evaluation Invasive evaluation of CSF physiology Spinal tap test (STT) Continuous spinal or ventricular drainage Infusion test Intracranial pressure (ICP) measurements iNPH grading scales Outcome Final thoughts 11 Core imaging in adult hydrocephalus Introduction Conventional X-rays Ultrasonography CT imaging Diagnosis of hydrocephalus Volumetric analysis (VA) by CT or MRI of the CSF spaces Postoperative management: shunt malfunction MRI Phase-contrast MRI MRI with gadolinium enhancement Radionuclide shunt patency test 12 Imaging of the cerebrospinal fluid circulation Imaging of flows Temporal normalization Aliasing correction CSF flow parameters CSF and blood flow interaction Imaging of CSF disorders 13 Cerebrospinal fluid dynamics and infusion techniques Introduction CSF dynamics Lumbar infusion techniques Bolus injection Volume removal Gradual infusion methods Constant flow infusion Constant pressure infusion External lumbar drainage and tap test Discussion Conclusions 14 Monitoring of intracranial pressure and assessment of cerebrospinal fluid dynamics Main mechanisms and models of CSF circulation and pressure–volume compensation ICP monitoring Pulse waveform Assessment of B waves Cerebrospinal pressure–volume compensatory reserve – RAP index Cerebrovascular pressure reactivity (PRx) Example of clinical use of ICP monitoring: pediatric hydrocephalus CSF dynamics: infusion test Rout and baseline CSF pressure Elastance coefficient (or elasticity) Analysis of slow waves, compensatory reserve, and pressure reactivity during infusion study Who needs a shunt: CSF dynamics perspective Vascular components of CSF circulation Transcranial Doppler-derived pressure autoregulation CO2 reactivity Cerebral blood flow studies Conclusion Acknowledgments 15 Cerebrospinal fluid biomarkers in idiopathic normal pressure hydrocephalus History of setting up biomarkers in idiopathic normal pressure hydrocephalus Rationale for their use Diagnostic versus prognostic biomarkers CSF biomarkers in the differential diagnosis with Alzheimer’s dementia CSF biomarkers in the differential diagnosis with vascular dementia CSF biomarkers in the differential diagnosis with Parkinson’s disease Prognostic biomarkers Summary of current evidence Summary of currently available evidence Experimental problems Quo vadis? Section 4 Treatment and outcomes 16 Hydrocephalus shunt procedures Introduction Valves Antisiphon devices (ASD) General surgical principles and postoperative care Proximal catheter placement Ventricular catheter insertion Procedure Discussion and complications Distal catheter insertion Peritoneal catheter insertion Procedure Discussion and complications Atrial catheter insertion Procedure Discussion and complications Pleural catheter insertion Procedure Discussion and complications Other distal catheter locations Lumbar catheter insertion Procedure Discussion and complications Shunt infections Conclusion 17 Hydrocephalus shunts Hardware Laboratory shunt testing Testing protocol Hydrodynamic properties of contemporary shunts Shunt testing in vivo Shunt registry The future of shunt technology Acknowledgments 18 Management of shunts in normal pressure hydrocephalus Introduction Types of shunt complications Underdrainage and overdrainage Imaging Shunt complication rates Ventriculoperitoneal shunt complications and infections in NPH patients Shunt infections Common pathogens and common sources of shunt infections and their sequelae Treatment strategies aimed at reducing shunt infection rates Conclusion 19 Endoscopic third ventriculostomy Indications and outcome ETV in adult patients ETV in children and the role of age and etiology dependence ETV in previously shunted patients ETV in communicating hydrocephalus ETV in idiopathic normal pressure hydrocephalus Intraoperative factors influencing the success of ETV Definition of success after ETV and diagnosis of ETV failure Management of ETV failure Advantages/disadvantages of ETV compared to VP shunt placement Preoperative planning and anatomic eligibility for ETV MRI: flow dynamics measurement Surgical technique of ETV, avoidance of complications Reported complications Postoperative care and follow-up Summary 20 Outcome of idiopathic normal pressure hydrocephalus Introduction Proper selection criteria for diagnosis of iNPH Deficiencies in identifying the degree of clinical impairment and therefore clinical improvement Standardized management protocols related to outcome Shunt management Standardized outcome assessment The time period for short-term and long-term outcome Clinical judgment Impact of complications after surgery Impact of comorbidities Conclusion Section 5 Associated conditions 21 Normal pressure hydrocephalus syndrome secondary to hemorrhage, infection, and malignancy The syndrome of compensated hydrocephalus Late-onset idiopathic aqueductal stenosis (LIAS) The syndrome of longstanding overt ventriculomegaly (LOVA) and the syndrome of hydrocephalus in young and middle-aged adults (SHYMA) Hydrocephalus secondary to other processes Hydrocephalus and malignancies Hydrocephalus following subarachnoid hemorrhage (SAH) Hydrocephalus following infection (post-infective) Conclusion 22 Low-pressure syndromes and cerebrospinal fluid leaks Epidemiology Pathogenesis Clinical presentation Positional headaches Miscellaneous symptoms Diagnosis Cranial computed tomography Cranial magnetic resonance imaging Myelography Radionuclide cisternography Spinal MRI Lumbar puncture Diagnostic criteria Treatment, outcomes, and future directions 23 Management of the adult with congenital hydrocephalus Introduction Transitioning neurosurgical care Pediatric neurosurgery perspective Adult neurosurgery perspective Patient and family perspective Recommendations Achieving shunt independence Endoscopic third ventriculostomy (ETV) ETV failure and complications Management of chronically shunted patients Slit ventricle syndrome (SVS) Management strategies Clinical and neuropsychological outcomes Clinical outcomes Neuropsychological outcomes 24 Management of hydrocephalus with associated cerebrospinal fluid pathologies Introduction Case 1. Hydrocephalus associated with a posterior fossa cyst Case 2. Posterior fossa cyst without hydrocephalus Case 3. Hydrocephalus associated with Chiari I malformation Case 4. Normal pressure hydrocephalus associated with cerebellar arachnoid cyst Case 5. Hydrocephalus with multiple arachnoid cysts Case 6. Hydrocephalus associated with a giant suprasellar arachnoid cyst diagnosed in a fetus Case synopsis and discussion The role of cognition and cognitive assessment The role of neuroimaging and MRI The role of multimodal surgical management The role of disease classification Conclusions Acknowledgments 25 Chiari malformation and hydrocephalus in adults Introduction What is the Chiari I malformation? Hydrocephalus and Chiari I: which came first? Hydrocephalus and the Chiari II malformation The Chiari I malformation and benign intracranial hypertension or pseudotumor cerebri Conclusion 26 Pseudotumor cerebri syndrome History Nomenclature Dandy criteria (modified) Clinical features Signs Associated conditions Investigations Neuroradiology Lumbar puncture CSF composition Pathophysiology Management Medical interventions Surgical interventions Conclusions Acknowledgments Conflict of interest Epilogue Index Plate