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.

Biopsy for Idiopathic normal pressure hydrocephalus diagnosis

Biopsy for Idiopathic normal pressure hydrocephalus diagnosis

Comorbid Alzheimer disease (AD) and Idiopathic normal pressure hydrocephalus (iNPH) is not uncommon, and the likelihood of each is increased with the presence of hypertension and advancing age. AD pathology is present in cortical biopsy of 75% of those iNPH patients with significant dementia at the time of shunt surgery 1).

Brain biopsy from 32 patients with idiopathic normal pressure hydrocephalus were investigated by light and electron microscope. Biopsies were made in 3 points (the cortex, subcortical and periventricular white matter during ventricular catheter positioning).

A number of pathological features of idiopathic normal pressure hydrocephalus were identified. Most frequent were the exhaustion of brain tissue, enlargement of perivascular spaces, aseptic necrosis, and amyloid and Lewy bodies formation.

The changes in brain tissue of patients with idiopathic normal pressure hydrocephalus transform our views on its mechanisms. It becomes clear that idiopathic normal pressure hydrocephalus is part of common neurodegenerative disease process that has characteristic features affecting clinical manifestations of the disease 2).


A high prevalence of AD histopathological findings (19%) occurred in patients treated with shunts for NPH based on cortical brain biopsies performed during placement of CSF shunts. high-volume lumbar puncture (HVLP) results alone were not predictive of clinical outcome. However, cortical brain biopsy results and the presence of Alzheimer’s pathology had a strong correlation with success after CSF shunting. Thirteen percent of patients who initially had a normal cortical brain biopsy result had evidence of AD pathology on repeat biopsy, demonstrating the progressive nature of the disease 3).


A study population comprised 102 patients with possible NPH with cortical brain biopsies, ventricular and lumbar CSF samples, and DNA available. The final clinical diagnoses were: 53 iNPH (91% shunt-responders), 26 AD (10 mixed iNPH+AD), and 23 others. Biopsy samples were immunostained against Aβ and HPτ. CSF levels of AD-related biomarkers (Aβ42, p-tau, total tau), non-AD-related Aβ isoforms (Aβ38, Aβ40), sAPP isoforms (sAPPα, sAPPβ), proinflammatory cytokines (several interleukins (IL), interferon-gamma, monocyte chemoattractant protein-1, tumor necrosis factor-alpha) and biomarkers of neuronal damage (neurofilament light and myelin basic protein) were measured. All patients were genotyped for APOE.

Lumbar CSF levels of sAPPα were lower (p<0.05) in patients with shunt-responsive iNPH compared to non-iNPH patients. sAPPβ showed a similar trend (p = 0.06). CSF sAPP isoform levels showed no association to Aβ or HPτ in the brain biopsy. Quantified Aβ load in the brain biopsy showed a negative correlation with CSF levels of Aβ42 in ventricular (r = -0.295, p = 0.003) and lumbar (r = -0.356, p = 0.01) samples, while the levels of Aβ38 and Aβ40 showed no correlation. CSF levels of proinflammatory cytokines and biomarkers of neuronal damage did not associate to the brain biopsy findings, diagnosis, or shunt response. Higher lumbar/ventricular CSF IL-8 ratios (p<0.001) were seen in lumbar samples collected after ventriculostomy compared to the samples collected before the procedure.

The role of soluble amyloid precursor protein (sAPP) isoforms in iNPH seems to be independent from the amyloid cascade. No neuroinflammatory background was observed in iNPH or AD 4).


In 28 consecutive patients diagnosed with INPH and shunted according to clinical, radiological and cerebrospinal fluid dynamic criteria, concomitant disorders were carefully registered, with special emphasis on cerebrovascular disease (CVD) and possible Alzheimer’s disease. During shunt surgery, a frontal cerebral biopsy specimen was obtained and subsequently analysed for pathological changes.

One or several concurrent disorders were present in 89% of the patients, most often CVD (n = 17) and possible Alzheimer’s disease (n = 12), of which eight patients presented both, diagnosed according to the criteria of the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer’s Disease and Related Disorders Association. The shunt success rate was 33%. A clear tendency towards increasing prevalence of CVD or Alzheimer’s disease was found in the subgroups with no improvement or clinical deterioration compared with the patients improving after shunt surgery. The presence of CVD tended towards an unfavourable shunt outcome. The pathological parenchymal changes reflected the clinical diagnoses of comorbidity, and were described in about half of the biopsy specimens, with Alzheimer’s disease (n = 7) and vascular changes (n = 7) being the most common findings. However, no significant correlation was found with the clinical diagnoses of Alzheimer’s disease and CVD. The presence of cerebral comorbidity, whether diagnosed clinically or by brain biopsy, did not preclude clinical improvement after shunt operation.

A high prevalence of CVD and Alzheimer’s disease was found in patients shunted for INPH, which was reflected, although less commonly, by similar neuropathological biopsy findings. No significant correlation was found between the presence of comorbidity and shunt outcome. The findings support the perception of INPH as a multiaetiological clinical entity, possibly overlapping pathophysiologically with CVD and Alzheimer’s disease 5).

References

1)

Golomb J, Wisoff J, Miller DC, Boksay I, Kluger A, Weiner H, Salton J, Graves W. Alzheimer’s disease comorbidity in normal pressure hydrocephalus: prevalence and shunt response. J Neurol Neurosurg Psychiatry. 2000 Jun;68(6):778-81. PubMed PMID: 10811706; PubMed Central PMCID: PMC1736969.
2)

Gavrilov GV, Stanishevskiy AV, Gaydar BV, Paramonova NM, Gaykova ON, Svistov DV. [Pathological changes in human brain biopsies from patients with idiopathic normal pressure hydrocephalus]. Zh Nevrol Psikhiatr Im S S Korsakova. 2019;119(3):50-54. doi: 10.17116/jnevro201911903150. Russian. PubMed PMID: 31089095.
3)

Pomeraniec IJ, Bond AE, Lopes MB, Jane JA Sr. Concurrent Alzheimer’s pathology in patients with clinical normal pressure hydrocephalus: correlation of high-volume lumbar puncture results, cortical brain biopsies, and outcomes. J Neurosurg. 2016 Feb;124(2):382-8. doi: 10.3171/2015.2.JNS142318. Epub 2015 Sep 4. PubMed PMID: 26339853.
4)

Pyykkö OT, Lumela M, Rummukainen J, Nerg O, Seppälä TT, Herukka SK, Koivisto AM, Alafuzoff I, Puli L, Savolainen S, Soininen H, Jääskeläinen JE, Hiltunen M, Zetterberg H, Leinonen V. Cerebrospinal fluid biomarker and brain biopsy findings in idiopathic normal pressure hydrocephalus. PLoS One. 2014 Mar 17;9(3):e91974. doi: 10.1371/journal.pone.0091974. eCollection 2014. PubMed PMID: 24638077; PubMed Central PMCID: PMC3956805.
5)

Bech-Azeddine R, Høgh P, Juhler M, Gjerris F, Waldemar G. Idiopathic normal-pressure hydrocephalus: clinical comorbidity correlated with cerebral biopsy findings and outcome of cerebrospinal fluid shunting. J Neurol Neurosurg Psychiatry. 2007 Feb;78(2):157-61. Epub 2006 Sep 29. PubMed PMID: 17012342; PubMed Central PMCID: PMC2077673.

Hydrocephalus Classification

Hydrocephalus Classification

There is no international consensus on the classification of hydrocephalus, and there are various systems based on the age of onset, cerebrospinal fluid dynamics and anatomical area of accumulation, the levels of cerebrospinal fluid pressure and the presence of symptoms.

However, no definitive classification exists comprehensively to cover the variety of these aspects.

Wu et al. proposed a classification Based on Ventricular Pressure 1).


Walter Edward Dandy first described the basic mechanism and classification of hydrocephalus as:

Obstructive hydrocephalus or Non Obstructive hydrocephalus.

Despite advances in understanding of the underlying process, current classification systems still rely upon Dandy’s classification scheme 2).


The aim of a study was to evaluate the diagnostic utility of three-dimensional sampling perfection with application optimized contrast using different flip angle evolution (3D SPACE) sequence and Susceptibility Weighted Imaging (SWI) in hydrocephalus and to propose a refined definition and classification of hydrocephalus with relevance to the selection of treatment option.

A prospective study of 109 patients with hydrocephalus was performed with magnetic resonance imaging (MRI) brain using standardized institutional sequences along with additional sequences 3D SPACE and SWI. The images were independently read by two senior neuroradiologists and the etiopathogenesis of hydrocephalus was arrived by consensus.

With conventional sequences, 46 out of 109 patients of hydrocephalus were diagnosed as obstructive of which 21 patients showed direct signs of obstruction and 25 showed indirect signs. In the remaining 63 patients of communicating hydrocephalus, cause could not be found out in 41 patients. Whereas with 3D SPACE sequence, 88 patients were diagnosed as obstructive hydrocephalus in which all of them showed direct signs of obstruction and 21 patients were diagnosed as communicating hydrocephalus. By including SWI, we found out hemorrhage causing intraventricular obstruction in three patients and hemorrhage at various sites in 24 other patients. With these findings, we have classified the hydrocephalus into communicating and noncommunicating, with latter divided into intraventricular and extraventricular obstruction, which is very well pertaining to the selection of surgical option.

Chellathurai et al., strongly suggest to include 3D SPACE and SWI sequences in the set of routine MRI sequences, as they are powerful diagnostic tools and offer complementary information regarding the precise evaluation of the etiopathogenesis of hydrocephalus and have an effective impact in selecting the mode of management 3).

Terms used

Acquired hydrocephalus

Adult hydrocephalus

Arrested hydrocephalus or Compensated hydrocephalus

Chronic hydrocephalus

Communicating hydrocephalus or Non obstructive hydrocephalus

Congenital hydrocephalus

External hydrocephalus

Focal hydrocephalus

Hydrocephalus Ex Vacuo

Idiopathic normal pressure hydrocephalus

Infantile hydrocephalus or Pediatric hydrocephalus.

Internal hydrocephalus

Non obstructive hydrocephalus or Communicating hydrocephalus

Normal pressure hydrocephalus for Idiopathic normal pressure hydrocephalus or Secondary normal pressure hydrocephalus.

Obstructive hydrocephalus.

Pediatric hydrocephalus or Infantile hydrocephalus

Secondary normal pressure hydrocephalus.


With the rare exception of hydrocephalus associated with overproduction of CSF in patients with choroid plexus papillomas (CPPs), all hydrocephalus is basically obstructive hydrocephalus. That the rare CPP causes hydrocephalus is not debated, but why it does so is the subject of some discussion. CPPs are known to lead to increases in the rate of CSF production and are known to cause hydrocephalus.

Normal CSF absorptive mechanisms can clear the amount of spinal fluid produced in the ventricular system at extremely high rates without producing ventriculomegaly. If CSF production and ICP increase substantially, ventricular size increases 4). When CSF flow is obstructed in the context of increased CSF production, there is a great tendency for ventriculomegaly or hydrocephalus to develop. CPPs, in themselves, can create the only pure form of communicating hydrocephalus. However, that these tumors tend to be large and to restrict CSF flow through the foramen of Monro or aqueduct of Sylvius, is more likely to account for the severity of hydrocephalus in this context 5).

When hydrocephalus is severe, especially in the very young, it may not be possible to define the point of CSF obstruction without introducing tracers into the CSF pathways. In patients treated early in life whose ventricles have become smaller with treatment, it is possible to determine the first site of obstruction to CSF flow on MRI or CT.

Patients with complex congenital anomalies such as hydrocephalus related to a Chiari II malformation and spina bifida often have multiple sites of obstruction 6) 7). It may not be possible to predict a second or downstream point of obstruction. In these patients, only one point may be obstructed or all of these sites may be restricted.

Based on a analyses from a mathematical modeling, of the work on the circuitry of CSF flow, and these potential sites of obstruction, Rekate et al., proposed a classification

It is generally assumed that endoscopic third ventriculostomy (ETV) is only effective for treating obstructive hydrocephalus, and many assume that obstructive hydrocephalus is synonymous with aqueductal stenosis. The growing number of reports on the efficacy of ETV for treating “communicating hydrocephalus” has generated considerable consternation 8).


The “Multi-categorical Hydrocephalus Classification” (Mc HC), was invented and developed to cover the entire aspects of hydrocephalus with all considerable classification items and categories.

Ten categories include “Mc HC” category I: onset (age, phase), II: cause, III: underlying lesion, IV: symptomatology, V: pathophysiology 1-CSF circulation, VI: pathophysiology 2-ICP dynamics, VII: chronology, VII: post-shunt, VIII: post-endoscopic third ventriculostomy, and X: others. From a 100-year search of publication related to the classification of hydrocephalus, 14 representative publications were reviewed and divided into the 10 categories.

The Baumkuchen classification graph made from the round o’clock classification demonstrated the historical tendency of deviation to the categories in pathophysiology, either CSF or ICP dynamics.

In the preliminary clinical application, it was concluded that “Mc HC” is extremely effective in expressing the individual state with various categories in the past and present condition or among the compatible cases of hydrocephalus along with the possible chronological change in the future 9).

References

1)

Wu X, Zang D, Wu X, Sun Y, Yu J, Hu J. Diagnosis and Management for Secondary Low- or Negative-Pressure Hydrocephalus and a New Hydrocephalus Classification Based on Ventricular Pressure. World Neurosurg. 2019 Jan 4. pii: S1878-8750(18)32946-2. doi: 10.1016/j.wneu.2018.12.123. [Epub ahead of print] PubMed PMID: 30611954.
2)

Dandy WE, Blackfan KD. Internal hydrocephalus: an experimental, clinical and pathological study. Am J Dis Child. 1914;8(6):406-482.
3)

Chellathurai A, Subbiah K, Abdul Ajis BN, Balasubramaniam S, Gnanasigamani S. Role of 3D SPACE sequence and susceptibility weighted imaging in the evaluation of hydrocephalus and treatment-oriented refined classification of hydrocephalus. Indian J Radiol Imaging. 2018 Oct-Dec;28(4):385-394. doi: 10.4103/ijri.IJRI_161_18. PubMed PMID: 30662197; PubMed Central PMCID: PMC6319109.
4) , 5)

Rekate HL, Erwood S, Brodkey JA, Chizeck HJ, Spear T, Ko W, Montague F. Etiology of ventriculomegaly in choroid plexus papilloma. Pediatr Neurosci. 1985;12:196–201.
6)

Rekate HL. Neurosurgical management of the newborn with spinal bifida. In: Rekate HL, editor. Comprehensive Management of Spina Bifida. Boca Raton, FL, CRC Press; 1991. pp. 1–20.
7)

Rekate HL. Neurosurgical mangement of the child with spinal bifida. In: Rekate HL, editor. Comprehensive Management of Spina Bifida. Boca Raton, FL, CRC Press; 1991. pp. 93–112.
8)

Rekate HL. Selecting patients for endoscopic third ventriculostomy. Neurosurg Clin N Am. 2004;15:39–49. doi: 10.1016/S1042-3680(03)00074-3.
9)

Oi S. Classification of hydrocephalus: critical analysis of classification categories and advantages of “Multi-categorical Hydrocephalus Classification” (Mc HC). Childs Nerv Syst. 2011 Oct;27(10):1523-33. doi: 10.1007/s00381-011-1542-6. Epub 2011 Sep 17. Review. PubMed PMID: 21928018.
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