HYDROCEPHALUS.pptx

hydrocephalus, clinical features in various age groups, investigations, treatment options to create a basic understanding of the underlying pathology and management

1. HYDROCEPHALUS Dr. Rahul Jain SR Neurosurgery DEPTT OF NEUROSURGERY AIIMS PATNA

2. CSF Physiology It circulates within the subarachnoid space, between the arachnoid and the pial membranes. Function as a shock absorber for the CNS, may also serve an immunological function analogous to the lymphatic system. 80% of CSF is produced by the choroid plexuses, located in both lateral ventricles (accounts for ≈95 % of CSF produced in the choroid plexuses) and in the 4th ventricle. CSF is also produced by the ependymal lining of the ventricles, and in the spine, in the dura of the nerve root sleeves

3. Average Total CSF volume in the body is 150 ml. CSF is produced at rate of 0.3 ml/min (450 ml/24 hrs). Absorbed primarily by arachnoid villi (granulations) that extend into the dural venous sinuses. Other sites of absorption include the choroid plexuses and glymphatics . The rate of absorption is pressure-dependent.

4. Hydrocephalus An abnormal accumulation of cerebrospinal fluid within the ventricles of the brain. Estimated prevalence: 1–1.5 %. Hydrocephalus (HCP) is either due to subnormal CSF reabsorption or, rarely, CSF overproduction. subnormal CSF reabsorption. Two main functional subdivisions: 1. obstructive hydrocephalus (AKA non- communicating ): block proximal to the arachnoid granulations (AG).

5. 2. communicating hydrocephalus (AKA non-obstructive): defect in CSF reabsorption by the Arachnoid granulations. CSF overproduction: rare. As with some choroid plexus papillomas .

6. Signs and Symptoms sun-setting appearance of the eyes - this latter clinical sign is attributed to pressure on the mid-brain tectum by CSF in the supra-pineal recess

7. Prior to closure of the cranial sutures and obliteration of the fontanelle, hydrocephalus results in disproportionate head growth. Thus, over the first 2–3 years of life, measurement of the occipito -frontal circumference and plotting this on a centile chart provides a simple and sensitive test. Clinical symptoms are often subtle and include general irritability, poor feeding and slow attainment of milestones.

8. Other Signs Macewen’s sign: cracked pot sound on percussing over-dilated ventricles 6th nerve ( abducens ) palsy: the long intracranial course is postulated to render this nerve very sensitive to pressure. beaten copper skull (some refer to beaten silver appearance) on plain skull X-ray

9. Radiological Diagnosis the size of both temporal horns (TH) is ≥ 2mm in width Evans ratio or index: ratio of FH to maximal biparietal diameter (BPD) measured in the same CT slice: > 0.3 suggests hydrocephalus

10. Other radiological features ballooning of frontal horns of lateral ventricles (“Mickey Mouse” ventricles ) periventricular low density on CT sagittal MRI may show upward bowing of the corpus callosum

11. Management Medical treatment HCP remains a surgically treated condition. Acetazolamide ( C arbonic Anhydrase Inhibitor) may be helpful for temporizing the condition. watch for electrolyte imbalance and acetazolamide side effects: lethargy, tachypnea , diarrhea , paresthesias (e.g. tingling in the fingertips)

12. SURGICAL Goal - Normal sized ventricles are not the goal of therapy, Goals are optimum neurologic function (which usually requires normal intracranial pressure) and a good cosmetic result.

13. Surgical options Options include third ventriculostomy : currently, endoscopic method is preferred Shunting: VP shunts, VA shunt, ventriculopleural , LP shunt eliminating the obstruction: e.g. opening a stenosed Sylvian aqueduct. Often higher morbidity and lower success rate than simple CSF diversion with shunts, except perhaps in the case of tumor choroid plexectomy

14. QUESTIONS

15. Question 1 Which one of the following is the most common cause of congenital hydrocephalus? A. Craniosynostosis B. Intra uterine meningitis C. Aqueductal stenosis D. Malformations of great vein of Galen

16. Question 2 Which of the following is expected after subarachnoid hemorrhage over the convexities of the brain? 1. increased reabsorption of CSF by arachnoid villi 2. noncommunicating hydrocephalus 3. communicating hydrocephalus 4. increased production of CSF

17. Question 3 The following statements concern cerebrospinal fluid (CSF) formation : (which is correct) (a) None of the fluid originates from the brain substance. (b) lt ls largely formed by the choroid plexuses. (c) It ls passively secreted by the ependymal cells covering the choroid plexuses. (d ) It is produced continuously at a rate of about 5 ml/min. (e) It is drained into the subarachnoid space fromthe lymphatic vessels of the brain and spinal cord .

18. Question 4