cerebrospinal_fluid_shunt_malfunction

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Cerebrospinal fluid shunt malfunction

The most recent epidemiological study from the UK Shunt Registry demonstrates that 20% of cerebrospinal fluid shunt malfunction within 1 year of primary insertion, ranging from 31% in infants to 17.4% in adults 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).

The main reasons for shunt revision were undershunting and shunt infection, but shunt overdrainage and mechanical failure continue to pose problems.

Shunt overdrainage

Shunt disconnection

Shunt obstruction

Shunt migration

Undershunting

Ventricular catheter misplacement

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).

see Ventriculoperitoneal shunt malfunction

Cerebrospinal fluid shunt malfunction diagnosis.

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 7).

Shunt malfunction outcome.

Shunt dysfunction case series.

Shunt malfunction case reports.


1)
Fernández-Méndez R, Richards HK, Seeley HM, Pickard JD, Joannides AJ; UKSR collaborators. Current epidemiology of cerebrospinal fluid shunt surgery in the UK and Ireland (2004-2013). J Neurol Neurosurg Psychiatry. 2019 Jul;90(7):747-754. doi: 10.1136/jnnp-2018-319927. Epub 2019 Mar 25. PubMed PMID: 30910858; PubMed Central PMCID: PMC6585267.
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)
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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