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Hydrocephalus diagnosis and management
- 1.
- 2. Anatomy and Physiology VentricularSystem & CSF • 80% from the choroid plexus • Interstitial spaces Production • Ependymal lining • Dura of nerve root sheaths
- 3.
- 5. Anatomy and Physiology CSF •Absorbtion: - Primarily by the Arachnoid villi • Rate of production - 0.3ml/min or approx 450ml/24 hrs • Turnover: 3 times/day
- 7. CSF CIRCULATION • Lateralventricles – Foramen of Monro • 3rd Ventricle – Cerebral Acqueduct • 4th Ventricle – F. of Magendie & Luschka • Perimedullary and Perispinal subarachnoid spaces – upward to the basal cistern • Superior and lateral surfaces of the cerebral hemispheres
- 8.
- 9. CSF PRESSURE • TheCSF volume and pressure are maintained every minute by the systemic circulation • CSF pressure is in equilibrium with capillary pressure (arteriolar tone) • Hypoventilation – ↑ in blood PCO2 – ↓ pH & ↓ arteriolar resistance – ↑ cerebral blood flow – ↑ CSF pressure • Hyperventilation has the opposite effect
- 10. CSF PRESSURE • Normaladult intracranial pressure 2-8 mmHg • Up to 16 mmHg are considered normal • ICP higher than 40 mmHg or lower BP may combine to cause ischemic damage to the brain
- 11. Definition • An increasein CSF volume in an enlarged ventricular system resulting - primarily from decreased absorbtion - rarely b’coz of increased production • Prevalance: 1-1.5% • Incidence: 0.3-3.5% - Upto 20% after SAH - 1% after meningitis
- 12. Definition • Results inventricular enlargement • Lat ventricles - frontal and occipital horns • Volumes decrease in cerebral sulci, fissures and cisterns
- 13. Classification • Functional • Clinical •Age wise • Pathological • ICP/ R-out • Special Types
- 14. Functional • Communicating: - Blockat the level of the arachnoid granulations • Non-communicating: - Block proximal to the arachnoid granulations
- 15. Clinical • High pressurehydrocephalus - Acute - Chronic • Normal pressure hydrocephalus • Arrested hydrocephalus • Hydrocephalus ex vacuo
- 16. Age wise • Paediatric •Juvenile/Adult
- 17. Pathological • Congenital 1. Chiaritype 1 malformation 2. Chiari type 2 malformation and/or Meningimyelocele 3. Primary aqueductal stenosis 4. Secondary aqueductal gliosis ( germinal matrix hge) 5. Dandy Walker malformation 6. Rare X- linked disorder
- 18. Pathological • Acquired 1. Infectious -Post meningitic - Granuloma - Cysticercosis - Abscess 2. Post haemorrhagic - SAH - IVH - Trauma
- 19. Pathological • Acquired 3. Secondaryto mass effect - Non neoplastic - Neoplastic - Choroid plexus papilloma - Post operative - Neurosarcoidosis - Assoc with spinal tumours - Constitutional ventriculomegaly
- 20. ICP • High Pressure -Monitored ICP > 15mmhg - B waves - R out increased • Normal Pressure - Monitored ICP < 15mmHg - R out increased
- 21. Special Types HYYDROCEPHALUS EXVACUO • enlargement of the ventricles due to loss of cerebral tissue (cerebral atrophy) • usually as a function of normal ageing • Accelerated by Alzheimer's disease, Creutzfeldt-Jakob, Alcoholism
- 22. Special Types EXTERNAL HYDROCEPHALUS •enlarged subarachnoid spaces over the frontal poles in the first year of life • ventricles are normal or minimally enlarged • may be distinguished from subdural hematoma by the "cortical vein sign" • usually resolves spontaneously by 2 years of age • Etiology : • Unclear • Defect in CSF resorption is postulated • External hydrocephalus (EH) may be a variant of communicating hydrocephalus
- 23. Special Types ARRESTED HYDROCEPHALUS •Compensated hydrocephalus interchangeably • There is no progression or deleterious sequelae requiring CSF shunting • Criteriae in the absence of a CSF shunt: - Near normal ventricular size - Normal head growth curve - Continued psychomotor development
- 24. Special Types OTITIC HYDROCEPHALUS •Obsolete term • Describes the increased ICP in patients with otitis media
- 25. Special Types HYDRANENCEPHAL Y •A post-neurulation defect • Total or near-total absence ofthe cerebrum • Intact cranial vault and meninges • Intracranial cavity being filled with CSF • There is usually progressive macrocrania • Most commonly cited cause : B/L ICA infarcts • Infection - Congenital or neonatal herpes - Toxoplasmosis - Equine virus
- 26. Special Types ENTRAPPED FOURTHVENTRICLE • AKA isolated fourth ventricle, • 3rd Ventricle X 4th ventricle X Foramina of Luschka or Magendie - Post-infectious hydrocephalus( fungal) - Repeated shunt infections • Choroid plexus of the 4th ventricle : produces CSF which enlarges the ventricle
- 27. Special Types NPH • Classictriad: - Dementia - Gait disturbance - Urinary incontinence • Communicating hydrocephalus on CT or MRI • Normal pressure on random LP • Symptoms remediable with CSF shunting
- 28. NPH • Etiology - PostSAH - Post-traumatic - Post-meningitic - Following posterior fossa surgery - Tumors including carcinomatous meningitis - Also seen in -15% of patients with Alzheimer's disease - Deficiency of the arachnoid granulations - Aqueductal stenosis
- 29.
- 30. INFANCY • Head growsat alarming rate with hydrocephalus. – First sign: Bulging pulsatile fontanelles – Tense, non-pulsatile anterior fontanelle – Dilated scalp veins – Thin skull bones with separated sutures • Cracked pot sounds on percussion : Mc Ewans sign
- 31. INFANCY • Depressed eyesor SUN SET sign – Eyes downward with sclera visible above • Pupils sluggish with unequal response to light • Irritability, lethargy, feeds poorly, • Changes in Level of Consciousness • Arching of back (Opisthotonus) • Lower extremity spasticity
- 32. INFANCY • Brain StemCompression – Swallowing difficulties, Stridor, Apnea, Aspiration, Respiratory difficulties • Lower Brainstem Dysfunction – Difficulty in sucking and feeding – High-pitched shrill cry
- 33. INFANCY • Emesis, Somnolence,Seizures, and Cardio Pulmonary Distress • Severely affected infants may not survive neonatal period
- 34. CHILDHOOD • Headache onawakening, improvement following emesis or sitting • Papilledema, strabismus, and Extrapyramidal signs, ataxia • Irritability, Lethargy, Apathy, Confusion, and often incoherent
- 35. SYMPTOMS AND SIGNS •Irritability • Poor feeding • Headache • Nausea, vomiting • Diplopia • Visual impairment • Dementia • Incontinence • Gait disturbances • Accelerated head growth • Bulging fontanelles • Forced down gaze • Developmental delay • Exotropia • Papilledema • Posturing • Bradycardia • Apnea / Death
- 36. Evaluation • Clinical • CT •MRI • ICP • R (out) • Isotope cisternography
- 37. Clinical • Occipito FrontalCircumference - OFC of a normal infant = Distance from Crown to Rump • Indicators: - Crossing curves - Head growth > 1.25cm/wk - OFC approaching 2 SD above normal - Out of proportion with body length or weight, even if normal for age
- 40.
- 41. CT CRITERIAE <40% -Normal FH/ID 40-50% - Borderline > 50% - Hydrocephalus
- 42.
- 43. CT/ MRI Findings AcuteHydrocephalus • Preferential AP dilatation of the Temporal Horns > 2mm • Ballooning of the Frontal Horns and 3rd Ventricles (Mickey Mouse sign) • Periventricular interstitial edema • Flattening of the Inter-hemispheric and Sylvian fissures • Upward bowing of corpus callosum on sagittal MRI • 4th Ventricle normal in size
- 44. CT/ MRI Findings ChronicHydrocephalus • Temporal horns may be less prominent • 3rd ventricle may herniate into Sella Turcica • Erosion of Sella • Corpus callosum atrophy • Irreversible white matter demyelination
- 45. R (Out) • Assessesthe degree of blockage to CSF absorbtion back into the blood stream • Simultaneous infusion of artificial CSF and measurement of ICP • Spinal subarachnoid space cannulated • ICP monitor inserted • Calculated resistance value high Better response to surgery
- 46. Isotope Cisternography • Radioisotopeinjected into Lumbar Sub- arachnoid space • Absorbtion of CSF monitored periodically over 96 hrs • Positive cisternogram does not predict response to shunt surgery
- 47.
- 48. THERAPEUTIC MANAGEMENT • Goals: –Relieve hydrocephaly – Treat complications – Manage psychomotor problems – Usually surgical
- 49. Drug Therapy • Thechoroid plexus shares many ion pumps and enzyme systems with renal tubular epithelium – Acetazolamide: Start @ 25mg/kg/day PO TID Increase @ 25mg/kg/day to 100mg/kg/day Simultaneously start Frusemide @1mg/kg/day
- 50. Drug Therapy Tocounteract acidosis: • tricitrate (Polycitra®) 4 ml/kg/day divided QID (each ml is equivalent to 2 mEq of bicarbonate, and contains 1 mEq K+ and 1 mEq Na+) • measure serial electrolytes, and adjust dosage to maintain serum HC03 > 18 mEqIL . • change to Polycitra-K® (2 mEq K+ per ml, no Na+) ifserum potassium becomes low • or to sodium bicarbonate if serum sodium becomes low
- 51. Drug Therapy • Watchfor electrolyte imbalance and acetazolamide side effects: - Lethargy - tachypnea - diarrhea - paresthesias • Perform weekly CT scan and insert ventricular shunt if progressive ventriculomegaly occurs. • Otherwise, maintain therapy for a 6 month trial, then taper dosage over 2-4 weeks
- 52. Spinal Taps • HCPafter IVH may be transient • Serial taps (ventricular or LP) may temporize until resorption resumes • LPs only for Communicating HCP • No reabsorption when the protein content of the CSF is < 100 mg/dl Spontaneous resorption unlikely SHUNTING
- 53. Surgical Modalities 1. ChoroidPlexectomy 2. 3rd Ventriculostomy 3. Shunts
- 54. Choroid Plexectomy • Describedby Dandy in 1918 for communicating hydrocephalus • May reduce the rate but does not totally halt CSF production • Open surgery associated with a high mortality rate • Endoscopic choroid plexus coagulation - 1910
- 55. 3rd Ventriculostomy • Resurgenceof interest in third ventriculostomy (TV) with the recent increased use ofventriculoscopic surgery • Indications: - Obstructive HCP. - Mgt of shunt infection - Subdural hematomas after shunting - Slit ventricle syndrome
- 56. 3rd Ventriculostomy • Contraindications: -Communicating Hydrocepalus - Tumor - Previous shunt - Previous SAH - Previous whole brain radiation - Significant adhesions visible when perforating through the floor of the 3rd ventricle at the time of performance of TV
- 57. 3rd Ventriculostomy • Complications -Hypothalamic injury - Transient 3rd and 6th nerve palsies - Uncontrollable bleeding - Cardiac arrest - Traumatic basilar artery aneurysm
- 58.
- 59. Types of Shunt ShuntTypes By Category a. VP Shunt » Most commonly used shunt in modern era » Lateral ventricle is the usual proximal location » Intraperitoneal pressure b. Ventriculo-atrial shunt (Vascular shunt) » Through jugular veins to sup. Vena cava » Treatment of choice in abdominal abnormalities
- 60. c. Torkildsen shunt: »Shuntingventricle to cisternal space »Rarely used »Effective only in acquired obstructive hydrocephalus d. Miscellaneous: »Pleural space »Gall bladder »Ureter/Urinary Bladder
- 61. e. Lumbo-peritoneal shunt: »Onlyfor communicating hydrocephalous f. Cyst/Subdural-Peritoneal shunt: »Draining arachnoid cyst/subdural hygroma cavity
- 62. SHUNT MATERIALS • Shuntsare composed of Silastic material made from silicone.
- 63. VP SHUNT • Shuntsystems include three components: – Ventricular catheter – One way valve – Distal catheter • The ventricular catheter – Straight piece of tube – Closed on the proximal end – With multiple holes upto 2cm for the entry of CSF
- 64. VA Shunt • TheVA shunt – Must be accurately located – Requires frequent revisions – Distal end position to be maintained – Infection may be more serious
- 65. VP SHUNT • Ifboth the VPS & VAS do not function to absorb CSF the shunt have to placed in the pleural space
- 66. POST-OP CARE • Observefor signs of Increased ICP – Assessment pupil size – Cushing’s Reflex – Abdominal distention • due to CSF peritonitis or post-op ileus due to catheter placement.
- 67. Complications i. General: a. Obstruction b.Disconnection c. Infection d. Erosion through Skin e. Seizures f. Metastatic route g. Silicone allergy
- 68. • VP Shunt -Inguinal hernia - Hydrocele - Peritonitis - Intestinal Obstruction - Volvulus - Migration of tip to scrotum/ bowel/ stomach - Malposition of tip - Over-shunting - Needs frequent length adjustment
- 69. VA shunt: – Requiresrepeated lengthening: – High risk of infection/septicaemia: – Risk of retrograde flow of blood: in case of valve malfunction (rare) – Shunt embolus – Vascular complications: perforation, thrombophlebitis, pulmonary micro-emboli
- 70. LP Shunt: – Laminectomyincurs 15% chance of scoliosis – Progressive cerebellar tonsillar herniation (up to 70%) – Slit ventricle syndrome – Overshunting is harder to control – Difficult proximal end revision (if required: – Lumber radiculopathy – CSF leak – Difficult pressure regulation – Bilateral 6th, 7th, nerve dysfunction due to overshunting – High incidence of arachnoiditis & adhesions
Editor's Notes
- #20 vascular malformations, arachnoid cysts Medulloblastomas, suprsellar & pituitary tumours Post op: Post fossa tumours
- #60 Shunts TYPES OF SHUNTS SHUNT TYPE BY CATEGORY 1. ventriculoperitoneal (VP) shunt: A. most commonly used shunt in modern era B. lateral ventricle is the usual proximal location C. intraperitoneal pressure: normal is near atmospheric 2. ventriculo-atrial (VA) shunt (“vascular shunt”): A. shunts ventricles through jugular vein to superior vena cava, so-called “ventriculo-atrial” shunt because it shunts the cerebral ventricles to the vascular system with the catheter tip in the region of the right cardiac atrium) B. treatment of choice when abdominal abnormalities are present (extensive abdominal surgery, peritonitis, morbid obesity, in preemies who have had NEC and may not tolerate VP shunt…) C. shorter length of tubing results in lower distal pressure and less siphon effect than VP shunt, however pulsatile pressures may alter CSF hydrodynamics 3.
- #61 3: Torkildsen shunt: A. shunts ventricle to cisternal space B. rarely used C. effective only in acquired obstructive HCP, as patients with congenital HCP frequently do not develop normal subarachnoid CSF pathways 4. miscellaneous: various distal projections used historically or in patients who have had significant problems with traditional shunt locations (e.g. peritonitis with VP shunt, SBE with vascular shunts): A. pleural space (ventriculopleural shunt): not a first choice, but a viable alternative if the peritoneum is not available. To avoid symptomatic hydrothorax necessitating relocating distal end, it is recommended only for patients > 7 yrs age. Pressure in pleural space is less than atmospheric B. gall bladder C. ureter or bladder: causes electrolyte imbalances due to losses through urine 5. lumboperitoneal (LP) shunt A. only for communicating HCP: primarily pseudotumor cerebri or CSF fistula37. Useful in situations with small ventricles B. over age 2 yrs, percutaneous insertion with Tuohy needle is preferred 6. cyst or subdural shunt: from arachnoid cyst or subdural hygroma cavity, usually to peritoneum
- #68 Disadvantages/complications of various shunts 1. those that may occur with any shunt: A. obstruction: the most common cause of shunt malfunction proximal: ventricular catheter (the most common site) valve mechanism distal: reported incidence of 12-34%. Occurs in peritoneal catheter in VP shunt (see below), in atrial catheter in VA shunt B. disconnection at a junction, or break at any point C. infection D. hardware erosion through skin, usually only in debilitated patients (especially preemies with enlarged heads and thin scalp from chronic HCP, who lay on one side of head due to elongated cranium). May also indicate silicone allergy (see below) E. seizures (ventricular shunts only): there is ≈ 5.5% risk of seizures in the first year after placement of a shunt which drops to ≈ 1.1% after the 3rd year39 (NB: this does not mean that the shunt was the cause of all of these seizures). Seizure risk is questionably higher with frontal catheters than with parieto-occipital F. act as a conduit for extraneural metastases of certain tumours (e.g. medulloblastoma). This is probably a relatively low risk40 G. silicone allergy41: rare (if it occurs at all). May resemble shunt infection with skin breakdown and fungating granulomas. CSF is initially sterile but later infections may occur. May require fabrication of a custom silicone-free device (e.g. polyurethane)
- #70 . VA shunt: A. requires repeated lengthening in growing child B. higher risk of infection, septicemia C. possible retrograde flow of blood into ventricles if valve malfunctions (rare) D. shunt embolus E. vascular complications: perforation, thrombophlebitis, pulmonary micro-emboli may cause pulmonary hypertension (incidence ≈ 0.3%)
- #71 4. LP shunt: A. if at all possible, should not be used in growing child unless ventricular access is unavailable (e.g. due to slit ventricles) because of: laminectomy in children causes scoliosis in 14%; risk of progressive cerebellar tonsillar herniation (Chiari I malformation) in up to 70% of cases B. overshunting harder to control when it occurs (a special horizontal-vertical (H-V) valve increases resistance when upright, see below) C. difficult access to proximal end for revision or assessment of patency (see Lumboperitoneal (LP) shunt evaluation, page 214) D. lumbar nerve root irritation (radiculopathy) E. leakage of CSF around catheter F. pressure regulation is difficult G. bilateral 6th and even 7th cranial nerve dysfunction from overshunting H. high incidence of arachnoiditis and adhesions