Cerebrospinal fluid shunt malfunction diagnosis

Cerebrospinal fluid shunt malfunction diagnosis

The diagnosis of cerebrospinal fluid shunt malfunction based on a careful clinical history, examination, and investigations such as computed tomography (CT) scanning and plain X-ray shunt series is not always straightforward 1).

For example, ventricular size may not change in cases with a blocked shunt. Pumping a shunt prechamber is notoriously unreliable and potentially dangerous 2).

Admission for observation is expensive and excessive CT scanning carries a radiation burden. Many patients may be admitted and subjected to CT scanning on multiple occasions. There is a need to develop more reliable methods of assessing shunt function and monitoring intracranial pressure (ICP) 3) 4) 5) 6) 7) 8).

Optic nerve sheath diameter may be assessed using ultrasound or magnetic resonance imaging (MRI). Implantable ICP sensors within a shunt system have been blighted by poor long-term stability. Long-term studies of the recently introduced Raumedic NEUROVENT-P-tel and the Miethke SENSOR RESERVOIR are awaited with a keen interest 9).


Several attempts have been made to measure the cerebrospinal fluid flow velocity utilizing different Phase contrast magnetic resonance imaging techniques. In a study, König et al. evaluated 3T (Tesla) MRI scanners for their effectiveness in determining of flow in the parenchymal portion of ventricular shunt systems with adjustable valves containing magnets.

At first, an MRI phantom was used to measure the phase-contrasts at different constant low flow rates. The next step was to measure the CSF flow in patients treated with ventricular shunts without suspected malfunction of the shunt under observation.

The measurements of the phantom showed a linear correlation between the CSF flow and corresponding phase values. Despite many artifacts resulting from the magnetic valves, the ventricular catheter within the parenchymal portion of shunt was not superimposed by artifacts at each PC MRI plane and clearly distinguishable in 9 of 12 patients. Three patients suffering from obstructive hydrocephalus showed a clear flow signal.

Cerebrospinal fluid flow detected within the parenchymal portion of the shunt by phase contrast magnetic resonance imaging may reliably provide information about the functional status of a ventricular shunt. Even in patients whose hydrocephalus was treated with magnetic adjustable valves, the CSF flow was detectable using PC MRI sequences at 3 T field strength 10).


Non-invasive techniques to assess ‘semi-quantitatively’ whether intracranial pressure is raised or not include optic nerve sheath diameter (ultrasound or MRI), tympanic membrane displacement and transcranial Doppler but none have yet been shown to be sufficiently accurate for routine clinical use in patients with potential shunt malfunction. Provision of a separate subcutaneous CSF reservoir is of proven benefit in allowing access to the cerebral ventricles to measure ICP and allow removal of CSF in an emergency


Various invasive diagnostic test procedures for the verification of shunt function have been described:

Invasive CSF pressure and flow measurements

CSF tap test and drip interval test

Infusion tests

Radioactive shuntogram.

By comparison, publications addressing the noninvasive pumping test are rare.

Noninvasive pumping test of all formerly published results are values derived from tests with a variety of reservoirs and valves (at least 2 types).

In a few reports, the shunt/reservoir type used is not even specified, although the technical parameters of such reservoirs and valves are obviously essential.

To judge occlusions distally from the reservoir other authors have had to close the pVC transcutaneously by manual compression.

This is never possible with a sufficient certainty and, if ever undertaken, it usually does provide a source of error.


Rapid cranial MRI was not inferior to CT for diagnosing ventricular shunt malfunction and offers the advantage of sparing a child ionizing radiation exposure 11).


1)

Spirig JM, Frank MN, Regli L, Stieglitz LH (2017) Shunt agerelated complications in adult patients with suspected shunt dysfunction . A recommended diagnostic workup. 1421–1428
2)

Bromby A, Czosnyka Z, Allin D, Richards HK, Pickard JD, Czosnyka M (2007) Laboratory study on “intracranial hypotension” created by pumping the chamber of a hydrocephalus shunt. Cerebrospinal Fluid Res 9:1–9
3)

Dupepe EB, Hopson B, Johnston JM, Rozzelle CJ, Oakes WJ, Blount JP, Rocque BG (2016) Rate of shunt revision as a function of age in patients with shunted hydrocephalus due to myelomeningocele. Neurosurg Focus 41(November):1–6
4)

Korinek AM, Fulla-Oller L, Boch AL, Golmard JL, Hadiji B, Puybasset L (2011) Morbidity of ventricular cerebrospinal fluid shunt surgery in adults: an 8-year study. Neurosurgery 68(4):985–994
5)

Paulsen AH, Lundar T, Lindegaard KF (2015) Pediatric hydrocephalus: 40-year outcomes in 128 hydrocephalic patients treated with shunts during childhood. Assessment of surgical outcome, work participation, and health-related quality of life. J NeurosurgeryPediatrics 16(6):633–641
6)

Richards H, Seeley H, Pickard J (2009) Who should perform shunt surgery? Data from the UK Shunt Registry. Cerebrospinal Fluid Res 6:S31
7)

Spiegelman L, Asija R, Da Silva SL, Krieger MD, McComb JG (2014) What is the risk of infecting a cerebrospinal fluid–diverting shunt with percutaneous tapping? J Neurosurg Pediatr 14(4):336– 339
8)

Tamber MS, Klimo P, Mazzola CA, Flannery AM (2014) Pediatric hydrocephalus: systematic literature review and evidence-based guidelines. Part 8: management of cerebrospinal fluid shunt infection. J Neurosurg Pediatr 14(Suppl1):60–71
9)

Antes S, Stadie A, Müller S, Linsler S, Breuskin D, Oertel J (2018) Intracranial Pressure–Guided Shunt Valve Adjustments with the Miethke Sensor Reservoir. World Neurosur 642–650
10)

König RE, Stucht D, Baecke S, Rashidi A, Speck O, Sandalcioglu IE, Luchtmann M. Phase-Contrast MRI Detection of Ventricular Shunt CSF Flow: Proof of Principle. J Neuroimaging. 2020 Nov 4. doi: 10.1111/jon.12794. Epub ahead of print. PMID: 33146931.
11)

Boyle TP, Paldino MJ, Kimia AA, Fitz BM, Madsen JR, Monuteaux MC, Nigrovic LE. Comparison of rapid cranial MRI to CT for ventricular shunt malfunction. Pediatrics. 2014 Jul;134(1):e47-54. doi: 10.1542/peds.2013-3739. Epub 2014 Jun 2. PubMed PMID: 24918222.

Shunt malfunction

Shunt malfunction

Cerebrospinal fluid diversion by way of ventriculoperitoneal shunt (or other terminus) is a commonly performed neurosurgical procedure but one that is fraught with high rates of failure. Up to one-third of adult patients undergoing CSF shunting will experience a shunt failure 1).

Shunt dysfunction or failure was defined as shunt revision, subsequent endoscopic third ventriculostomy, or shunt infection 2).

Mechanical shunt obstruction is the most common reason for failure, and in proximal catheter failure, this typically means obstruction by the choroid plexus 3).

Shunt surgery consumes a large amount of pediatric neurosurgical health care resources. Although many studies have sought to identify risk factors for shunt failure, there is no consensus within the literature on variables that are predictive or protective.

Patients with cerebrospinal fluid shunts frequently present to the emergency department (ED) with suspected shunt malfunction.

Once there is a suspicion of a shunt dysfunction, a CT scan or MRI scan is used to compare the ventricular size and show the most definitive signs of a malfunction. This is only useful if a previous scan can be used for comparison. In cases where the symptoms of a shunt malfunction are present but the scanning shows no evidence, the next step involves a shunt tap test.

Mechanical failure-which is the primary cause of CSF shunt malfunction-is not readily diagnosed, and the specific reasons for mechanical failure are not easily discerned. Prior attempts to measure cerebrospinal fluid flow noninvasively have lacked the ability to either quantitatively or qualitatively obtain data.

To address these needs, a preliminary study evaluates an ultrasonic transit time flow sensor in pediatric and adult patients with external ventricular drainages (EVDs). One goal was to confirm the stated accuracy of the sensor in a clinical setting. A second goal was to observe the sensor’s capability to record real-time continuous CSF flow. The final goal was to observe recordings during instances of flow blockage or lack of flow in order to determine the sensor’s ability to identify these changes.

A total of 5 pediatric and 11 adult patients who had received EVDs for the treatment of hydrocephalus were studied in a hospital setting. The primary EVD was connected to a secondary study EVD that contained a fluid-filled pressure transducer and an in-line transit time flow sensor. Comparisons were made between the weight of the drainage bag and the flow measured via the sensor in order to confirm its accuracy. Data from the pressure transducer and the flow sensor were recorded continuously at 100 Hz for a period of 24 hours by a data acquisition system, while the hourly CSF flow into the drip chamber was recorded manually. Changes in the patient’s neurological status and their time points were noted.

The flow sensor demonstrated a proven accuracy of ± 15% or ± 2 ml/hr. The flow sensor allowed real-time continuous flow waveform data recordings. Dynamic analysis of CSF flow waveforms allowed the calculation of the pressure-volume index. Lastly, the sensor was able to diagnose a blocked catheter and distinguish between the blockage and lack of flow.

The Transonic flow sensor accurately measures CSF output within ± 15% or ± 2 ml/hr, diagnoses the blockage or lack of flow, and records real-time continuous flow data in patients with EVDs. Calculations of a wide variety of diagnostic parameters can be made from the waveform recordings, including resistance and compliance of the ventricular catheters and the compliance of the brain. The sensor’s clinical applications may be of particular importance to the noninvasive diagnosis of shunt malfunctions with the development of an implantable device 4).

Classification

Shunt overdrainage

Shunt disconnection

Shunt obstruction

Shunt migration

Ventricular catheter misplacement

see Ventriculoperitoneal shunt malfunction

Distal shunt malfunction due to a mechanical failure is a common reason for shunt revision 5).

As many as one third of patients presenting with shunt malfunction will not have the diagnosis of shunt malfunction supported by a prospective radiologic interpretation of brain imaging. Although the neurosurgical community can assess the clinical situation to determine the need for surgery, other clinicians can be easily reassured by a radiographic report that does not mention or diagnose shunt malfunction. Today, more than ever, nonneurosurgeons are being called on to evaluate complex clinical situations and may rely on radiographic reports 6).

Diagnosis

Various invasive diagnostic test procedures for the verification of shunt function have been described:

Invasive CSF pressure and flow measurements

CSF tap test and drip interval test

Infusion tests

Radioactive shuntogram.

By comparison, publications addressing the noninvasive pumping test are rare.

Noninvasive pumping test of all formerly published results are values derived from tests with a variety of reservoirs and valves (at least 2 types).

In a few reports, the shunt/reservoir type used is not even specified, although the technical parameters of such reservoirs and valves are obviously essential.

To judge occlusions distally from the reservoir other authors have had to close the pVC transcutaneously by manual compression.

This is never possible with a sufficient certainty and, if ever undertaken, it usually does provide a source of error.


Rapid cranial MRI was not inferior to CT for diagnosing ventricular shunt malfunction and offers the advantage of sparing a child ionizing radiation exposure 7).

Treatment

ETV can be considered a primary treatment modality in children with shunt malfunction and has a good success rate in cases presenting with closure of previously performed ETV stoma 8).

Outcome

Case series

Case reports

1)

Reddy GK, Bollam P, Shi R, Guthikonda B, Nanda A: Management of adult hydrocephalus with ventriculoperitoneal shunts: long-term single-institution experience. Neurosurgery 69:774–781, 2011
2)

Riva-Cambrin J, Kestle JR, Holubkov R, Butler J, Kulkarni AV, Drake J, Whitehead WE, Wellons JC 3rd, Shannon CN, Tamber MS, Limbrick DD Jr, Rozzelle C, Browd SR, Simon TD; Hydrocephalus Clinical Research Network. Risk factors for shunt malfunction in pediatric hydrocephalus: a multicenter prospective cohort study. J Neurosurg Pediatr. 2016 Apr;17(4):382-90. doi: 10.3171/2015.6.PEDS14670. Epub 2015 Dec 4. PubMed PMID: 26636251.
3)

Korinek AM, Fulla-Oller L, Boch AL, Golmard JL, Hadiji B, Puybasset L: Morbidity of ventricular cerebrospinal fluid shunt surgery in adults: an 8-year study. Neurosurgery 68:985–995, 2011
4)

Pennell T, Yi JL, Kaufman BA, Krishnamurthy S. Noninvasive measurement of cerebrospinal fluid flow using an ultrasonic transit time flow sensor: a preliminary study. J Neurosurg Pediatr. 2016 Mar;17(3):270-7. doi: 10.3171/2015.7.PEDS1577. Epub 2015 Nov 13. PubMed PMID: 26565943.
5)

Sribnick EA, Sklar FH, Wrubel DM. A Novel Technique for Distal Shunt Revision: Retrospective Analysis of Guidewire-Assisted Distal Catheter Replacement. Neurosurgery. 2015 May 1. [Epub ahead of print] PubMed PMID: 25938689.
6)

Iskandar BJ, McLaughlin C, Mapstone TB, Grabb PA, Oakes WJ. Pitfalls in the diagnosis of ventricular shunt dysfunction: radiology reports and ventricular size. Pediatrics. 1998 Jun;101(6):1031-6. PubMed PMID: 9606231.
7)

Boyle TP, Paldino MJ, Kimia AA, Fitz BM, Madsen JR, Monuteaux MC, Nigrovic LE. Comparison of rapid cranial MRI to CT for ventricular shunt malfunction. Pediatrics. 2014 Jul;134(1):e47-54. doi: 10.1542/peds.2013-3739. Epub 2014 Jun 2. PubMed PMID: 24918222.
8)

Shaikh S, Deopujari CE, Karmarkar V, Muley K, Mohanty C. Role of Secondary Endoscopic Third Ventriculostomy in Children: Review of an Institutional Experience. Pediatr Neurosurg. 2019 Jun 3:1-8. doi: 10.1159/000500641. [Epub ahead of print] PubMed PMID: 31158842.
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