Emergency Evaluation of Hydrocephalus Shunt Patients The Society of Neurological Surgeons Bootcamp

Communicating vs. Obstructive Hydrocephalus Communicating Hydrocephalus All 4 ventricles are enlarged Causes: IVH of prematurity (grade III/IV), adult IVH, aneurysmal SAH, meningitis May do lumbar puncture Obstructive Hydrocephalus Dilatation of lateral and third ventricles with small, compressed or normal size 4th ventricle Asymmetry or enlargement of lateral ventricle when obstruction is at Foramen of Monro ( e.g. colloid cyst) Posterior fossa mass lesions (tumor, ICH, cyst), intraventricular mass lesions (tumor, IVH, cyst), aqueductal stenosis Do NOT do lumbar puncture

Communicating Hydrocephalus Enlargement of lateral, 3rd, and 4th ventricles Note sulcal effacement, temp horns, rounded 3rd, and enlarged 4th

Obstructive Hydrocephalus Aqueductal stenosis Note enlarged frontal horns, temporal tip dilation, rounded 3rd but small or normal 4th ventricle

Shunt Technology Pressure differential valves Antisiphon valves Flow regulated valves Programmable valves OSV

CSF Shunt Malfunction: Infants Progressive macrocephaly Tense anterior fontanelle Sutural splaying Downgaze, lid retraction Esotropia (VIth nerve palsy) In infants, CSF shunt malfunction may also be characterized by …

CSF Shunt Malfunction: Children Developmental delay Decline in school performance (esp. verbal IQ) Visual loss In children, other findings may also be present, including …

Radiology Compare ventricular size to “well” baseline Infants: Trans-fontanelle ultrasound CT MRI Shunt x-ray series Disconnection or fracture of tubing Shunt malfunction is principally a clinical diagnosis. However, confirmatory radiological studies are important, and are also needed to plan surgical repair of malfunctioning shunts. Axial imaging should be compared to well baseline scans. In infants, ultrasound may be used to assess ventricular size. In older children, CT or MR imaging is appropriate. Shunt radiographs are obtained to evaluate for disconnection.

Invasive Studies CSF shunt tap Radionuclide shuntogram Assess flow and pressure (although proximal obstruction may commonly interfere with accuracy) Send CSF for GS/Cx, Glu/Pro, cell counts if infection suspected Relieve pressure if obstructed distally Radionuclide shuntogram Assess proximal and distal flow Ventricular reflux and outflow each correlate with appropriate function (but test is imperfect) Intracranial pressure monitoring Invasive studies may also be useful in specific cases …

CSF Shunt Infection Organisms Therapy Staph. Epi (40%) Staph. Aureus (20%) Gram Negatives Diptheroids Yeast Therapy Externalize shunt Change hardware Antibiotics Consider LP CSF shunt infection is most often related to contamination at the time of implantation or revision. The most common organisms are …. Therapy for CSF shunt infection commonly involves …

Differential Diagnosis of Shunt Infection Gastroenteritis Often associated with sick contacts, diarrhea Otitis May often be detected on physical examination Urinary tract infection Important to differentiate from colonization in spina bifida patients Patients with hydrocephalus may of course present with symptoms not ultimately related to the shunt. Common differential diagnoses include … Nevertheless, it is paramount that shunt malfunction be carefully considered and close surveillance undertaken whenever the status of the shunt is in doubt.

CSF Shunt Complications: Mechanical Failure Blockage Choroid plexus Ependyma Fracture Disconnection Valve failure Proximal failure due to blockage is the most common etiology of shunt malfunction. Blockage is most commonly caused by adhesions to the choroid plexus or the ependyma. Mechanical failure may also be caused by …

CSF Shunt Complications: Mechanical Failure Distal failure Kinked tubing Malabsorption Pleural effusion Cor pulmonale Shunt nephritis Distal CSF shunt malfunction may occur due to kinked tubing or failure of the distal absorptive cavity: malabsorption in the peritoneal space or pleural effusion, or due to heart failure or shunt nephritis for shunts in the atrial position.

CSF Shunt Complications: Abdominal failure Umbilical hernia Extra-peritoneal catheter Bowel perforation In addition to malabsorption, peritoneal complications may result from promotion of an umbilical or inguinal hernia, failure to introduce the distal catheter fully into the peritoneal space (or migration out of the peritoneum), or due to bowel perforation.

CSF Shunt Complications: Overdrainage Postural (Low pressure) headache Subdural hygroma Craniostenosis CSF shunts may also cause complications due to over drainage, including postural headache, the formation of chronic, proteinaceous subdural hygromas (sometimes symptomatic due to significant mass effect), or secondary cranial synostosis.

CSF Shunt Complications: Hemorrhage Parenchymal damage Raised ICP IVH: Valve obstruction Ependymal adhesions and multicompartmental hydrocephalus Shunt revision or trauma may also result in shunt-related intracerebral or intraventricular hemorrhage. In addition to causing parenchymal damage and raised intracranial pressure, intraventricular hemorrhage may also further impair shunt function (typically due to valve obstruction). In the long term, intraventricular hemorrhage may also make hydrocephalus more difficult to treat by causing loculated CSF spaces and ependymal adhesions.

Shunt Evaluation Protocol: History Hydrocephalus etiology Exact date of last tap or revision Symptoms of last failure Seizure disorder? Latex allergy? Current Symptoms Headache Severity/location Positional Morning Mental status changes Fever Shuntalgia Nausea/vomiting Intercurrent illness It is important to obtain a thorough directed history from any patient suspected of a shunt malfunction. The history should include … Specific characterization of key symptoms is also important to differentiate between shunt malfunction and other differential diagnoses. Headache should be investigated to determine severity and location on the head (typically bifrontal and/or occipital in shunt malfunction), positional character (typically dependent headache in shunt malfunction), or morning headaches. The history should also specifically seek any …

Shunt Evaluation Protocol: Diagnostic Studies Non-contrast head CT scan (shunt protocol) or ‘quick brain’ MRI Shunt x-ray series Abdominal ultrasound, if indicated Shunt tap, if indicated Formal skin preparation 25g butterfly needle: test OP and valsalva (OP may be obscured by proximal obstruction) CSF sample for GS/Cx, Cell count, Glu/Prot Standard diagnostic studies include axial imaging of the brain, to assess ventricular size, cisternal effacement, transependymal fluid, and other findings related to hydrocephalus. Comparison to well baseline studies should be undertaken whenever possible. Identification of the exact dates of recent shunt operations and the dates comparison scans were obtained is imperative. For example, two scans obtained on a single day may show significantly different ventricular size when one is obtained just before and one hours after an urgent shunt revision surgery. Many institutions are using ‘flash sequence’ or ‘quick brain’ MRI for evaluation of patients with CSF shunts. These studies yield only limited images of the brain parenchyma, but are generally excellent for visualizing the size and configuration of the ventricular system. They can generally be done without sedation (sometimes with a parent holding their infant’s head still during image acquisition). The principal advantage is avoiding repeated delivery of radiation to patients with CSF shunts, which poses long term risks of cataracts and perhaps even radiation induced malignancy. If CT imaging is used, doses should be scaled appropriately for age and the gantry angled to avoid radiation to the globes. Shunt radiographs (in AP and lateral views) are important to rule out shunt fracture, kinking or termination short of the abdomen. They also reveal the brand and setting of the shunt valve. Patients suspected of chronic infection may undergo abdominal ultrasound or abdominal CT to rule out shunt-associated pseudocyst. Again, ultrasound has the advantage of avoiding radiation exposure. The position of the distal shunt relative to any fluid collection may be evaluated by comparing the ultrasound to the shunt radiographs if necessary. If shunt infection is suspected, performance of a shunt tap to collect CSF samples is indicated. Although some information about function can be gleaned from shunt tap (or tap with radionuclide shuntogram) it is important to remember that partial proximal obstruction may result in significantly misleading findings. For a shunt tap, the skin should be carefully prepared and the tap performed using a 25g butterfly needle, with testing of opening pressure and response to valsalva, plus collection of CSF samples to evaluate for infection. Samples should be sent if possible for gram stain and culture, cell count, and glucose and protein.

Shunt Evaluation Protocol: Admission Immediate intervention for: Definite, acute malfunction Pain Infection Bradycardia Decreased mental and/or vision Cardiorespiratory monitoring Frequent neurological checks NPO except meds Anti-microbial shampoo Consider steroid prep for latex allergy Immediate operative intervention is indicated for patients with … When patients with CSF shunts are admitted for further observation and work-up, or after shunt revision surgery, the should be carefully monitored, in a setting with nurses who are familiar with the care of hydrocephalus patients and using cardiorespiratory monitoring and frequent neurological checks. If appropriate, these patients should be maintained on NPO status, have an antimicrobial shampoo in preparation for possible surgery, and be administered a steroid prep if they have a documented latex allergy (in addition to full latex exposure precautions).

Conclusions Involve experienced team members in significant care decisions When in doubt, keep the patient for observation Listen to parents Myelomeningocele patients may have protean forms of presentation and increased risk for sudden deterioration Remember that, above all, shunt malfunction is a clinical diagnosis, supported by imaging studies and other data Care of hydrocephalus patients with CSF shunts generally occurs in a complex systems-based care environment. Therefore, it is useful to develop institutional protocols for these evaluations. In addition, it is important to ….

Case 1 History 6 y.o. with post-hemorrhagic hydrocephalus 3 days progressive fever and malaise Intermittent right sided headaches Last revision 3 years ago for obtundation The following four cases are designed to illustrate some common scenarios in evaluation of pediatric patients with CSF shunts. Case 1 …

Case 1 Physical Examination Imaging Diagnosis Irritable Neurological exam non-focal Temperature 102.5 F. Inflamed right tympanic membrane with effusion Imaging Axial imaging: ventricles unchanged from last well scan Shunt x-rays without disconnection Diagnosis Otitis media No surgical intervention

Case 2 History Physical Examination Radiology 10 y.o. with myelomeningocele and hydrocephalus One week of progressive frontal headaches and neck pain One day of vomiting Mother states these are typical malfunction symptoms Last revision distant Physical Examination Alert Baseline No papilledema Radiology Axial imaging unchanged from well baseline (small ventricles) Shunt x-rays without disconnection

Case 2 Diagnosis VP shunt malfunction Total proximal shunt obstruction was observed at surgery

Case 3 History Physical Examination 10 y.o. brought to E.R. by ambulance, obtunded EMT: “Has a shunt for hydrocephalus; had headaches at home for last few days” Physical Examination Unresponsive RR 15, labored HR 70 Pupils 4 mm, sluggish Frontal valve-reservoir palpable

Case 3 Diagnosis Treatment E.R. Course Severe ventricular shunt malfunction Treatment Neurosurgeon attempts to drain CSF; shunt tap is dry 1 gram/kg mannitol is given E.R. Course Intubated During CT, heart rate drops to 40