Neekhil A Patel

DESH negative normal pressure hydrocephalus: can patients still benefit from shunt insertion?

Selecting probable idiopathic normal pressure hydrocephalus (INPH) patients for shunt insertion presents a challenge because of coexisting comorbidities and other conditions that could mimic NPH. The characteristic appearance of DESH (Disproportionately Enlarged Subarachnoid Space Hydrocephalus) on brain imaging has been shown to have a high positive predictive value in identifying shunt responsive INPH patients (SINPHONI trial). However, the negative predictive value of this radiological sign was not clearly demonstrated.

Three-hundred cases of Spiegelberg ICP monitoring for hydrocephalus and CSF disorders: the Queen Square experience

Results ICPM was undertaken for a number of different conditions including undiagnosed headache (20.4%), IIH (28.7%), NPH (5.3%), high-pressure hydrocephalus (eg congenital/ post-traumatic/post-SAH) (17.2%) and Chiari malformations/syringomyelia (13.6%). Indications for ICPM included headache (74.0%), visual disturbance (6.2%), gait disturbance (6.2%) and cognitive disturbance (5.0%). Mean monitoring time was 37.3 hrs (range 12-154 hrs). Monitoring was conducted in the presence of a CSF shunt (50.6%), venous stent (3.7%) and previous cranial decompression (6.5%). Dynamic monitoring (eg with different shunt settings or pre/post venous stent insertion) was undertaken in 12.4%. Outcomes from ICPM included insertion of new CSF shunt (21.0%), revision of CSF shunt (13.0%), insertion of venous stent (6.5%), insertion of and lumbar drains for infusion studies (3.6%); importantly, non-operative treatment was pursued in a number of cases including shunt valve adjustment (7.7%) and conservative management (29.9%). Complications included superficial infection (4 patients, 1.2%), symptomatic intracerebral haematoma (1 patient, 0.3%) and misplacement (3 patients, 0.9%); importantly, there were no cases of deep intracranial infection and the only case of seizures was in the patient with the intracerebral haematoma. Conclusion This is the largest known series of ICPM for CSF disorders. It shows that ICP monitoring is a safe procedure and may be undertaken as part of routine protocol in the management of complex hydrocephalus patients. The number of cases that were subsequently managed conservatively or with a simple valve adjustment (37.6%) indicates the utility in terms of reducing operative interventions. Further evaluation of positive and negative predictive values based on the results of ICP monitoring and health-economic analyses will push the case for routine ICP monitoring prior to definitive management of all hydrocephalus patients.

The predictive value of DESH for shunt responsiveness in idiopathic normal pressure hydrocephalus

OBJECTIVE Selecting probable idiopathic normal pressure hydrocephalus (INPH) patients for shunt insertion presents a challenge because of coexisting comorbidities and other conditions that could mimic NPH. The characteristic appearance of DESH (Disproportionately Enlarged Subarachnoid Space Hydrocephalus) on brain imaging has been shown to have a high positive predictive value in identifying shunt responsive INPH patients (SINPHONI trial). However, the negative predictive value of this radiological sign was not clearly demonstrated. The aim of the present study was to calculate the negative predictive value of the DESH sign. METHODS A single centre study of probable INPH patients, who underwent ventriculoperitoneal (VP) shunt insertion. Shunt responsive INPH patients were identified as those having improvement in their walking speed, neuropsychological assessment and continence one year post operatively. Preoperative images were reviewed for DESH sign. Negative and Positive Predictive Values (NPV and PPV) of DESH sign were determined post analysis. RESULTS A total of 103 probable INPH patients were included (31 were DESH positive (30%) and 72 were DESH negative (70%)). A total of 78 patients showed measurable improvement one year post shunt insertion (76%); 24 (31%) of these patients were DESH positive and 54 (69%) were DESH negative (p=<0.001). Therefore, the DESH sign had an estimated PPV of 77% and NPV of 25%. CONCLUSION DESH sign demonstrates a low negative predictive value. We conclude that DESH negative patients should still undergo prognostic tests for iNPH, such as an extended lumbar drainage protocol, and should not be excluded from shunt insertion.

Venous sinus stenting immediately reduces intracranial pressure in Idiopathic Intracranial Hypertension patients with venous sinus stenosis

Idiopathic Intracranial Hypertension (IIH) is characterised by an increased intracranial pressure (ICP) in the absence of any central nervous system disease or structural abnormality, and normal CSF composition. Management becomes complicated once surgical intervention is required. Venous sinus stenosis has been suggested as a possible aetiology for IIH. Venous sinus stenting has emerged as a possible interventional option. Evidence for venous sinus stenting is based on elimination of the venous pressure gradient and clinical response. There have been no studies demonstrating the immediate effect of venous stenting on ICP.

Intracranial pressure and venous sinus pressure gradients: what happens 3 months after stenting?

Benign Intracranial hypertension (BIH) is commonly associated with venous sinus stenosis. Increasingly, this is treated endovascularly with stent insertion. However, this treatment modality is still controversial. Clinical improvement post stent insertion has been described. Little is known about long-term control of intracranial pressure (ICP). In our unit, catheter cerebral venogram with pressure measurements is routinely performed 3 months post stent insertion in BIH patients. We aim to quantify the degree of venous pressure changes in stenosis patients treated with sinus stenting and how the changes correlate with radiographic improvements.

Differential compartment overdrainage syndrome

We describe a consistently similar clinical presentation of patients with complex hydrocephalus and encysted fourth ventricle separately drained by infratentorial shunt insertion.

Cerebral venous sinus stent insertion as a primary versus secondary procedure in the treatment of intracranial hypertension.

Venous sinus stent insertion is being increasingly used as a primary treatment for intracranial hypertension patients (BIH). However, the value of this treatment modality is still controversial. This study looks into the difference in effectiveness of stents inserted as a primary procedure and those inserted in patients who already had cerebrospinal fluid diverting shunt in place i.e. as a secondary procedure.

Learning to control ICP

The landmark discovery that control of autonomic physiology could be ‘learned’ using biofeedback was first demonstrated with heart rate [1,2]. Biofeedback control has since been demonstrated with physiological variables such as regional cerebral blood flow, and end tidal carbon dioxide, with therapeutic application in conditions including migraine and epilepsy [3-6]. Here, we demonstrate for the first time, learned control of intracranial pressure (ICP), in a single patient using biofeedback of simultaneous ICP recordings via a Speigelberg™ intracranial pressure monitor.

Shunt assistant device deception due to pseudovertical posturing

The ever present need to balance over drainage with under drainage in hydrocephalus has required innovations including adjustable valves with antigravity devices. These are activated in the vertical position to prevent siphoning. We describe a group of patients who presented with unexplained under drainage caused by activation of antigravity shunt components produced by peculiar head/body position.

Cerebrospinal fluid biomarkers in patients with idiopathic normal pressure hydrocephalus with temporary response to shunt insertion

Obstruction to cerebrospinal fluid (CSF) flow in idiopathic normal pressure hydrocephalus (iNPH) results in reduced CSF total tau (t-tau) and amyloid-β 42 (Aβ42) protein concentrations [1]. Restoration of normal CSF flow dynamics with ventriculoperitoneal (VP) shunt allows these biomarkers to clear from extracellular fluid into the CSF(1). CSF biomarkers in iNPH have been an interesting subject with initials results suggestive of reduced t-tau and amyloid-β. A subgroup of probable iNPH patients responds favorably to VP shunt insertion but for a brief period (temporary responders). In our unit, these patients are further investigated with assessment of the effect of shunt tapping on walking speed. A large proportion underwent shunt revision. In this population, CSF biomarkers were studied over a prolonged period of time.