Implementation of a number recognition algorithm built using a neural network on the BASYS3 FPGA panel

In recent years, some field programmable valve arrays (FPGAs) based on CNN release phase accelerators have been introduced. FPGA is widely used in portable devices. They can be programmed to achieve higher concurrency and provide better performance. The power consumption of the FPGA is lower than that of GPUs with the same workload. These reasons make the FPGA suitable for implementing the CNN release phase. They can provide relative output performance for GPUs and achieve low power consumption, which is very important for portable devices. To effectively implement the CNN output phase on the FPGA, the design should have high parallelism, and the hardware resources used should be minimized to reduce the area and power consumption. In the process of working with the help of a neural network, an algorithm for recognizing handwritten numbers is implemented. A special architecture is being created to implement a neural network at the appatent level. The performance during operation and power consumption is comparable to the performance of the processor and the GPU.

Outcomes of Ventriculoperitoneal Shunt in Patients With Idiopathic Normal-Pressure Hydrocephalus 2 Years After Surgery

Objective: To evaluate the outcomes and prognostic factors of ventriculoperitoneal shunts (VP-shunts) in patients with idiopathic normal-pressure hydrocephalus (iNPH) at 6 months and 2 years after surgery.Method: We retrospectively analyzed 68 patients admitted to our institute and diagnosed with probable iNPH from January 2017 to March 2021. All patients underwent VP-shunt surgery with a programmable valve, and their outcomes were assessed via the Krauss index and modified Rankin scale (mRS) at 6 months and 2 years post-surgery. Univariate and multivariate regression analysis was performed to identify the prognostic factors.Results: The mean age of the patients was 71.1 ± 8.4 (mean ± standard deviation) years. On the Krauss improvement index, 6-month follow-up results were available for 68 patients. Of these patients, 91.2% experienced attenuation of their preoperative symptoms, with a mean Krauss index of 0.58 ± 0.27, and 48 patients (70.6%) had a Krauss index ≥0.5. Two-year follow-up results were available for 33 patients; 90.9% of them had sustained improvement, with a Krauss index of 0.54 ± 0.31, and 21 patients (66.3%) had a Krauss index ≥0.5. Thirty-three patients (58%) were living independently after 2 years (mRS 0–2). The outcomes were worse for patients with multiple comorbidities. Neither an increased patient age nor a prolonged history of illness was statistically significant prognostic factors for adverse outcomes of VP-shunt surgery.Conclusion: Surgical treatment was well-tolerated by patients with iNPH who received VP-shunts. Most patients experienced attenuation of their preoperative symptoms. Multiple concurrent comorbidities should be considered as adverse prognostic factors before shunt insertion in patients with iNPH.

Salomón Hakim, MD (1922–2011): A honeymoon with Neurosurgery

Salomón Hakim (1922–2011) was a Colombian neurosurgeon and brain scientist This biography examines the social and cultural background through which he emerged as an inquisitive and multi-dimensional surgeon-scientist, and his lifelong contributions to the specialty of neurosurgery. With empirical knowledge in applied medical physics, electronics, electricity and chemistry, he understood the paradoxical phenomenon of symptomatic hydrocephalus with normal cerebrospinal fluid pressure. This ultimately led Hakim to describe in exquisite detail the physics of the cranial cavity and brain hydrodynamics. His name is intertwined with the identification of the entity of a syndrome which had not previously been addressed in the medical literature: Normal Pressure Hydrocephalus (Hakim's syndrome). Additionally, he designed and built various models of valved shunting devices to treat the condition (eg the Hakim programmable valve). Through his selflessness and cogent work, Hakim left a legacy and intellectual heritage that has allowed many colleagues worldwide to save thousands of lives who would be otherwise condemned to oblivion.

Normal pressure hydrocephalus. Results of shunting correlated with diagnostic tests in 55 patients

Object: The purpose of this study was to evaluate the efficacy of ventricular shunting in normal pressure hydrocephalus (NPH). Methods: The authors retrospectively studied outcomes in NPH patients in whom shunts were implanted. At follow-up examinations up to one year, clinical symptoms were recorded according to a new NPH outcome rating scale, the modified Rankin score and the Mini-Mental State Examination. Comorbidities and complications during this period were also analyzed. Results: A total of 55 patients with NPH were included, with a male predominance (69% of men), an average age of 70 years. Comorbidities are multiple, hypertension is the most common factor in 55% of cases. 76% of patients are classified as having idiopathic NPH. The CSF tap test allows the evacuation of at least 40 ml of CSF and RCSF measurements in 55 patients. All these patients received a shunt withe programmable valve. An improvement in gait was observed in 88% of patients, 91% in balance and 84% in continence. The improvement in the field of neuropsychology is 34% after one year of shunt. 87% of patients were improved according to mRS. 27% of patients had complications and were treated conservatively or surgically. Conclusions: Ventricular shunt implantation is a safe procedure and can improve symptoms in 98% of patients with NPH in the medium term. Keywords: Cerebrospinal fluid (CSF) tap test; Normal pressure hydrocephalus (NPH); NPH assessment scores; Programmable valve; Symptomatic triade of Hakim

Risk factors for unchanged ventricles during pediatric shunt malfunction

OBJECTIVE Children whose ventricles do not change during shunt malfunction present a diagnostic dilemma. This study was performed to identify risk factors for unchanged ventricular size at shunt malfunction. METHODS This retrospective 1:1 age-matched case-control study identified children with shunted hydrocephalus who underwent shunt revision with intraoperative evidence of malfunction at one of the three participating institutions from 1997 to 2019. Cases were defined as patients with a change of < 0.05 in the frontal–occipital horn ratio (FOR) between malfunction and baseline, and controls included patients with FOR changes ≥ 0.05. The presence of infection, abdominal pseudocyst, pseudomeningocele, or wound drainage and lack of baseline cranial imaging at the time of malfunction warranted exclusion. RESULTS Of 450 included patients, 60% were male, 73% were Caucasian, and 67% had an occipital shunt. The median age was 4.3 (IQR 0.97–9.21) years at malfunction. On univariable analysis, unchanged ventricles at malfunction were associated with a frontal shunt (41% vs 28%, p < 0.001), programmable valve (17% vs 9%, p = 0.011), nonsiphoning shunt (85% vs 66%, p < 0.001), larger baseline FOR (0.44 ± 0.12 vs 0.38 ± 0.11, p < 0.001), no prior shunt infection (87% vs 76%, p = 0.003), and no prior shunt revisions (68% vs 52%, p < 0.001). On multivariable analysis with collinear variables removed, patients with a frontal shunt (OR 1.67, 95% CI 1.08–2.70, p = 0.037), programmable valve (OR 2.63, 95% CI 1.32–5.26, p = 0.007), nonsiphoning shunt at malfunction (OR 2.76, 95% CI 1.63–4.67, p < 0.001), larger baseline FOR (OR 3.13, 95% CI 2.21–4.43, p < 0.001), and no prior shunt infection (OR 2.34, 95% CI 1.27–4.30, p = 0.007) were more likely to have unchanged ventricles at malfunction. CONCLUSIONS In a multicenter cohort of children with shunt malfunction, those with a frontal shunt, programmable valve, nonsiphoning shunt, baseline large ventricles, and no prior shunt infection were more likely than others to have unchanged ventricles at shunt failure.

Infant hydrocephalus: what valve first?

Purpose To review the use of different valve types in infants with hydrocephalus, in doing so, determining whether an optimal valve choice exists for this patient cohort. Methods We conducted (1) a literature review for all studies describing valve types used (programmable vs. non-programmable, valve size, pressure) in infants (≤ 2 years) with hydrocephalus, (2) a review of data from the pivotal BASICS trial for infant patients and (3) a separate, institutional cohort study from Alder Hey Children’s Hospital NHS Foundation Trust. The primary outcome was any revision not due to infection. Results The search identified 19 studies that were included in the review. Most did not identify a superior valve choice between programmable and non-programmable, small compared to ultra-small, and differential pressure compared to flow-regulating valves. Five studies investigated a single-valve type without a comparator group. The BASICS data identified 391 infants, with no statistically significant difference between gravitational and programmable subgroups. The institutional data from our tertiary referral centre did not reveal any significant difference in failure rate between valve subtypes. Conclusion Our review highlights the challenges of valve selection in infant hydrocephalus, reiterating that the concept of an optimal valve choice in this group remains a controversial one. While the infant-hydrocephalic population is at high risk of valve failure, heterogeneity and a lack of direct comparison between valves in the literature limit our ability to draw meaningful conclusions. Data that does exist suggests at present that there is no difference in non-infective failure rate are increasing in number, with the British valve subtypes in infant hydrocephalus, supported by both the randomised trial and institutional data in this study.

In vitro testing of explanted shunt valves in hydrocephalic patients with suspected valve malfunction

Diagnosis of symptomatic valve malfunction in hydrocephalic patients treated with VP-Shunt (VPS) might be difficult. Clinical symptoms such as headache or nausea are nonspecific, hence cerebrospinal fluid (CSF) over- or underdrainage can only be suspected but not proven. Knowledge concerning valve malfunction is still limited. We aim to provide data on the flow characteristics of explanted shunt valves in patients with suspected valve malfunction. An in vitro shunt laboratory setup was used to analyze the explanted valves under conditions similar to those in an implanted VPS. The differential pressure (DP) of the valve was adjusted stepwise to 20, 10, 6, and 4 cmH2O. The flow rate of the explanted and the regular flow rate of an identical reference valve were evaluated at the respective DPs. Twelve valves of different types (Codman CertasPlus valve n = 3, Miethke Shuntassistant valve n = 4, Codman Hakim programmable valve n = 3, DP component of Miethke proGAV 2.0 valve n = 2) from eight hydrocephalic patients (four male), in whom valve malfunction was assumed between 2016 and 2017, were replaced with a new valve. Four patients suffered from idiopathic normal pressure (iNPH), three patients from malresorptive and one patient from obstructive hydrocephalus. Post-hoc analysis revealed a significant difference (p < 0.001) of the flow rate between each explanted valve and their corresponding reference valve, at each DP. In all patients, significant alterations of flow rates were demonstrated, verifying a valve malfunction, which could not be objectified by the diagnostic tools used in the clinical routine. In cases with obscure clinical VPS insufficiency, valve deficiency should be considered.

Efficacy and safety of the Miethke programmable differential pressure valve (proGAV®2.0): a single-centre retrospective analysis

Purpose Achieving decompression without CSF over-drainage remains a challenge in hydrocephalus. Differential pressure valves are a popular treatment modality, with evidence suggesting that incorporation of gravitational units helps minimise over-drainage. This study seeks to describe the utility of the proGAV®2.0 programmable valve in a paediatric population. Methods Clinical records and imaging of all patients fitted with proGAV®2.0 valves and Miethke fixed-pressure valves between 2014 and 2019 at our tertiary centre were analysed. Patient demographics, indication for shunt and valve insertion/revision and time to shunt/valve revision were collected. Ventricular linear metrics (fronto-occipital horn ratio (FOHR) and fronto-occipital horn width ratio (FOHWR)) were collected pre- and post-valve insertion. Microsoft Excel and SPSS v24 were used for data collection and statistical analysis. Results Eighty-eight proGAV®2.0 valves were inserted in a population of 77 patients (n = 45 males (58%), mean age 5.1 years (IQR: 0.4–11.0 years)). A total of 102 Miethke fixed-pressure valves were inserted over the same time period. Median follow-up was 17.5 months (1.0–47.3). One (1.1%) proGAV®2.0 was revised due to over-drainage, compared to 2 (1.9%) fixed-pressure valves (p > 0.05). ProGAV®2.0 insertion resulted in a significant decrease in the mean number of revisions per patient per year (1.77 vs 0.25; p = 0.01). Overall shunt system survival with the proGAV®2.0 was 80.4% at 12 months, and mean time to revision was 37.1 months, compared to 31.0 months (95%CI: 25.7–36.3) and 58.3% in fixed-pressure valves (p < 0.01). Significant decreases were seen following proGAV®2.0 insertion in both FOHR and FOHWR, by 0.014 (95%CI: 0.006–0.023, p = 0.002) and 0.037 (95%CI: 0.005–0.069, p = 0.024) respectively. Conclusion The proGAV®2.0 provides effective decompression of hydrocephalic patients, significantly reduces the number of valve revisions per patient and had a significantly greater mean time to revision than fixed-pressure valves.

Evaluation of smartphone-integrated magnetometers in detection of safe electromagnetic devices for use near programmable shunt valves: a proof-of-concept study

OBJECTIVE External magnetic forces can have an impact on programmable valve mechanisms and potentially alter the opening pressure. As wearable technology has begun to permeate mainstream living, there is a clear need to provide information regarding safety of these devices for use near a programmable valve (PV). The aim of this study was to evaluate the magnetic fields of reference devices using smartphone-integrated magnetometers and compare the results with published shunt tolerances. METHODS Five smartphones from different manufacturers were used to evaluate the magnetic properties of various commonly used (n = 6) and newer-generation (n = 10) devices using measurements generated from the internal smartphone magnetometers. PV tolerance testing using calibrated magnets of varying field strengths was also performed by smartphone magnetometers. RESULTS All tested smartphone-integrated magnetometers had a factory sensor saturation point at around 5000 µT or 50 Gauss (G). This is well below the threshold at which a magnet can potentially deprogram a shunt, based on manufacturer reports as well as the authors’ experimental data with a threshold of more than 300 G. While many of the devices did saturate the smartphone sensors at the source, the magnetic flux density of the objects decreases significantly at 2 inches. CONCLUSIONS The existence of an upper limit on the magnetometers of all the smartphones used, although well below the published deprogramming threshold for modern programmable valves, does not allow us to give precise recommendations on those devices that saturate the sensor. Based on the authors’ experimental data using smartphone-integrated magnetometers, they concluded that devices that measure < 40 G can be used safely close to a PV.

Standardization of cerebrospinal fluid shunt valves in pediatric hydrocephalus: an analysis of cost, operative time, length of stay, and shunt failure

OBJECTIVECSF shunts are the most common procedures performed in the pediatric neurosurgical population. Despite attempts in multiple studies, a superior shunt valve has never been shown. Because of this, the authors aim was to examine the impact of shunt valve standardization at their institution to determine if there is a difference in surgical cost, operative time, or short-term postoperative shunt failure.METHODSA retrospective analysis at the authors’ institution was performed for all new CSF diversion shunts, as well as shunt revisions requiring a new valve, or a new valve and at least a new proximal or distal catheter over a 1-year period (January 1, 2016, to December 31, 2016). After a period of transition, neurosurgeons were encouraged to use only one type of fixed-differential-pressure valve and one type of programmable valve when performing shunt surgeries. These patients who underwent “standardized” shunt surgery over a 1-year period (January 1, 2018, to December 31, 2018) were then compared to patients in the prestandardization epoch. All patients were followed for a 12-month period after surgery. Demographic information, surgical cost, operative time, and postoperative shunt failure data were collected in all patients in the study.RESULTSThe authors analyzed 87 shunt surgeries in patients prior to standardization and 94 shunt surgeries in patients after standardization. The rate of violation of the standardized shunt valve policy after implementation was 5.3% (5 of 94 procedures). When comparing the prestandardization group to those who received the standardized valve, operative costs were less ($1821.04 vs $1333.75, p = 0.0034). There was no difference in operative times between groups (78 minutes vs 81 minutes, p = 0.5501). There was no difference in total number of shunt failures between the two groups at 12 months after surgery (p = 0.0859). The rate of postoperative infection was consistent with the literature at 8%.CONCLUSIONSIn accordance with quality improvement principles, the reduction of unexplained clinical variance invariably leads to a decrease in cost and, more importantly, increased value. In this study, the implementation of a standardized shunt valve decreased operative cost. There were no differences in postoperative shunt failures at 12 months after surgery and no differences in length of surgery. Standardizing shunt valves in the treatment of pediatric hydrocephalus seems to be cost-effective and safe.