|Year : 2022 | Volume
| Issue : 2 | Page : 151-154
Correlation of palpation anterior fontanometry and cerebrospinal fluid opening pressure in early childhood hydrocephalus
Mesi Mathew1, Abdullahi Onimisi Jimoh1, Wilfred Chukwuemeka Mezue2, Enoch Ogbonnaya Uche2, Mark Chukwunweike Chikani2
1 Department of Surgery, Ahmadu Bello University Teaching Hospital, Zaria, Nigeria
2 Department of Surgery, University of Nigeria Teaching Hospital, Enugu, Nigeria
|Date of Submission||03-Dec-2021|
|Date of Decision||17-Feb-2022|
|Date of Acceptance||20-Feb-2022|
|Date of Web Publication||23-Apr-2022|
Department of Surgery, Ahmadu Bello University Teaching Hospital, Zaria
Source of Support: None, Conflict of Interest: None
Background: The anterior fontanelle (AF) tension has been a traditional clinical method of indirect assessment of intracranial pressure (ICP). How does this time-tested bedside assessment technique compare with an objective ventricular cerebrospinal fluid (CSF) opening pressure? Objective: To determine the correlation of palpation anterior fontanometry and CSF opening pressure in early childhood hydrocephalus. Materials and Methods: Children diagnosed with hydrocephalus who were planned for CSF diversion using ventriculo-peritoneal (V-P) shunt were prospectively studied over 18 months. The AF tension was assessed by palpation preoperatively and graded. The CSF opening pressure was measured using sterile disposable plastic manometers after ventricular cannulation intraoperatively. Statistical Analysis: Data obtained were analysed using SPSS version 21. Student's t-test, Mann–Whitney U test and ANOVA were used to determine associations based on normality tests. A P < 0.05 was considered significant for associations. Results: Fifty-two children were operated on with AF patency rate of 88.5%. Their age ranged between 2 weeks and 18 months with a mean age of 7.1 ± 5.1 months. The fontanelle tension was tense, full and normal in 63.0%, 26.1% and 10.9% of patients, respectively. The mean CSF opening pressure of 20.5 ± 8.5 cm of H2O was higher than the expected ICP for the age group (t-test 4.754, P = 0.000). All 28 patients with CSF opening pressure >15 cm of H2O had a tense fontanelle, but 10.9% of children with raised ICP have normal AF tension. Conclusion: The mean ICP increases as palpation AF tension increases, but a normal AF tension does not rule out raised ICP.
Keywords: Anterior fontanelle, fontanometry, hydrocephalus, intracranial pressure, manometry
|How to cite this article:|
Mathew M, Jimoh AO, Mezue WC, Uche EO, Chikani MC. Correlation of palpation anterior fontanometry and cerebrospinal fluid opening pressure in early childhood hydrocephalus. Niger Postgrad Med J 2022;29:151-4
|How to cite this URL:|
Mathew M, Jimoh AO, Mezue WC, Uche EO, Chikani MC. Correlation of palpation anterior fontanometry and cerebrospinal fluid opening pressure in early childhood hydrocephalus. Niger Postgrad Med J [serial online] 2022 [cited 2022 May 22];29:151-4. Available from: https://www.npmj.org/text.asp?2022/29/2/151/343739
| Introduction|| |
Hydrocephalus is a common condition encountered in neurosurgical practice with an estimated prevalence of 1%–1.5%, and incidence of 0.2–1.2/1000 births., Irrespective of the cause of hydrocephalus, cerebrospinal fluid (CSF) accumulation results in progressive increase in intracranial pressure (ICP) the rate of which dictates the urgency of intervention to prevent further neurological sequelae. In view of the detriments of raised ICP on the developing brain, physicians have used various physical examination findings in patients with hydrocephalus to assess ICP such as dilated scalp veins, bulging anterior fontanelle (AF), abducens nerve palsy, visual loss, hypertonia and hyperreflexia among others.,,
The AF is a rhomboid-shaped fibrous membrane-covering gap located at the junction between two parietal and two frontal bones. The AF offers insight into the newborn state of health, especially hydration and ICP status. Various techniques of fontanometry have been described; however, conventionally, ICP has been assessed by palpating the AF with the finger which has the advantage of being simple, cheap and devoid of detrimental effects., How does this time-tested clinical palpation method of the AF compare with a more objective CSF opening pressure measurement technique such as manometry?
| Materials and Methods|| |
The study was prospective hospital-based, which was conducted over 18 months from 1 July, 2017 to 22 January, 2019.
Approval for this study was obtained from the Health Research Ethics Committee (HREC) of Ahmadu Bello University Teaching Hospital (ABUTH), Zaria on the 9 February, 2017 with reference number ABUTHZ/HREC/Y7/2017. Informed consent from parents/guardians of patients who satisfy the inclusion criteria was obtained. Voluntary participation was emphasised to the participants in line with the Helsinki declaration for medical research on human subjects.
Study area and population
The study was carried out in the division of Neurosurgery, Surgery department of the ABUTH, Zaria Kaduna State, Nigeria. The hospital provides tertiary neurosurgical services to the entire population of Kaduna state and neighboring states of Katsina, Zamfara, Kano, Niger and beyond.
Kaduna state is located in the North-West region of Nigeria and has a population of 6.3 million and members of these communities are predominantly Hausa/Fulani mixed with several other tribes in these states and from across the country. Zaria metropolis is located on latitude 11.10°N and longitude 7.37°E, with an altitude of 2398 feet (730 m). The 2006 census population was estimated at 408, 198 with a population density of 1, 400/km2.
Sample size calculation
The sample size required to meet the set objectives at 95% confidence level was calculated from the Cochran's formula below:
n = the desired sample size
Z = the standard normal deviation corresponding to 95% level of confidence. The value obtained from the normal distribution is 1.96.
A pre-study review of the neurosurgical admission register showed the proportion of patients with symptomatic hydrocephalus admitted into the neurosurgical ward aged 0–5 years over 12 months (January-December 2016) was 3.1%.
Therefore, P = 0.031
q = 1 – 0.031 = 0.969
∂ = degree of accuracy desired (i.e. precision) is set at 5% (0.05)
The minimum sample size,
n = 46.16 = 46
Considering an attrition rate of 10%, 5 more patients were added to the recruits giving a minimum total of 51 patients.
Patient recruitment and data collection
Patients aged 0–5 years who have been radiologically confirmed to have hydrocephalus were prospectively enrolled in the study after consent was obtained from their parents/guardians. Relevant clinical data and examination of the AF tension were done for each child at presentation and repeated once the patient has been sent for from the operating room. Patients were resuscitated (where indicated) to ensure adequate hydration. The AF finding closest to the time of surgery was used for each of the patients. The fontanelle tension was subjectively assessed by palpation in quiet and calm children and the finding was reported as tense, full or normal AF described below: To minimise bias, the surgeon to measure intra-operative CSF pressure was blinded of the fontanometry finding.
- Tense fontanelle- bulges above the level of the bone edges and is sufficiently tense to cause difficulty in determining where bone ends
- Full fontanelle, which is clearly distinguishable from the surrounding bone edges
- Normal fontanelle clearly demarcates from bone edges, falls below the surface, and pulsates under the examining finger.
The CSF pressure was measured intraoperatively with a disposable plastic CSF manometer (PAJUNK® UK Medical Ltd) which was connected immediately after ventricular cannulation through a 3-way stopper. In general, the ventricular CSF pressure obtained by direct lateral ventricle cannulation is considered to be the ICP. The manometer was set at the level of the external auditory meatus, and the highest fluid meniscus level (in cm of H2O) was taken as the estimated ICP. The manometer was then be disconnected and discarded, and the V-P shunt procedure completed. The cut-off for raised ICP was designated to be >9.5cm H2O based on the normal ICP value range of the study population which is 3–7 mmHg (4.0–9.5 cm H2O).
Patients who were on acetazolamide or diuretics, and those whose parents/guardians declined consent were exempted from the study.
Retrieved data from only children with patent AF were analysed using IBM SPSS Statistics for Windows version 21 (IBM Corp., Armonk, N.Y., USA). Variables were analyzed using t-test, Mann–Whitney U test and ANOVA to determine associations depending on the normality test. The test for normality was performed using the Shapiro–Wilk test. A P < 0.05 was considered significant for statistical tests.
| Results|| |
Fifty-two children had ventriculo-peritoneal shunt for hydrocephalus for the study of which 46 (88.5%) had patent AF. Of the 46 enrolled patients, 27 (58.3%) were males, while 19 (41.3%) were females translating to a male-to-female ratio of 1.42:1. Their age ranged from 2 weeks to 18 months with a mean age of 7.1 ± 5.1 months. The mean occipitofrontal circumference was 57 cm for females and 54.2 cm for male children (Z = −2.012, P = 0.044, Mann–Whitney U test).
The AF was assessed to be normotensive in only 5 (10.9%) children [Table 1].
Cerebrospinal fluid opening pressure
The CSF opening pressure varied from 10 to 36.5 cm of H2O with a mean of 20.5 ± 8.5. The mean CSF opening pressure of 20.5 is significantly higher than the highest normal ICP for the patient age group which is >9.5 cmH2O (t-test 4.754, P = 0.000).
Fontanelle tension and cerebrospinal fluid opening pressure
Patients with tense AF had the highest mean CSF opening pressure [Table 2]. All 28 patients with CSF opening pressure >15 cm of H2O had a tense fontanelle.
|Table 2: One-way ANOVA for fontanelle tension and cerebrospinal fluid opening pressure|
Click here to view
| Discussion|| |
With 46 out of 52 patients that presented having patent AF, there is a fontanelle patency rate of 88.5%. All of the patients with patent AF were 18 months old or less in age. Therefore, palpation fontanometry of the AF can be applicable to the majority of children presenting for CSF diversion. Fontanelle assessment is important because in children in unfused cranial sutures, macrocephaly and bulging AF is the most common feature of chronic raised ICP. Infants with bulging AF have been shown to have 36% prevalence of clinically significant abnormal findings on neurosonography. Massager et al. also reported that AF pressure measured by Rotterdam transducer technique had a 100% sensitivity and specificity in determining infants with intracranial pathological processes.
Majority of our patients had a tense AF (63%) with a small proportion having a normal fontanelle tension (10.9%). The opening pressure of CSF varied between 10 and 36.5 cm of H2O among our patients. Usually, ICP shows significant variation with age among children. Normal ICP values for term infants, young children, older children and adults are 1.5–6.0 mmHg, 3–7 mmHg and <10–15 mmHg, respectively. None of our cohorts was an older child, hence the maximum normal pressure in the study population is expected to be 7 mmHg (9.5 cm of H2O). Consequently, all studied patients had raised ICP, and a CSF opening pressure of >9.5 cm of H2O could safely be considered as raised ICP in this study. The mean CSF opening pressure in this series was 20.5 cm of H2 O. The difference between this value and the maximum normal CSF for this patients group was found to be significant (t-test 4.754, P = 0.000). Hence, we can hypothesise that the CSF opening pressure among children with hydrocephalus is significantly higher than the normal value for age. This corroborates with findings by Gaab et al. who also reported a higher ventricular fluid pressure among patients with hydrocephalus compared to normal babies.
It is important to note that though all patients had raised ICP in this study, 5 (10.9%) were assessed to have normal AF tension highlighting the drawback of palpation fontanometry. In their study, Kaiser and Whitelaw used a fontanometer to assess the AF tension and concluded that caution needs to be applied in the interpretation of results as 9% of their patients were misclassified by the fontanometer despite yielding a clinically reliable impression of ICP in a high proportion of cases. When assessing the ICP in these groups of patients using the fontanelle tension, it is imperative to interpret the AF tension within the context of the overall patient symptomatology to avoid missing these categories of patients.
The mean CSF opening pressure showed steady increase and was highest in patients with tense fontanelle [Table 2]. Therefore, from our findings, patients with tense fontanelle are expected to have higher ICP compared to those with full fontanelle who in turn will have higher pressure when compared to those with normotensive fontanelle. Although this difference did not achieve statistical significance (P = 0.087), it cannot be pushed aside considering that 96.6% of patients with tense fontanelle had a CSF opening pressure >15 cm of H2O. In a study of the relationship between AF tension and clinical signs of infantile hydrocephalus, the authors found a tense fontanelle had the best correlation with the AF pressure. This is similar to the finding in our study. Contrarily, in another comparative study in 17 children, Kaiser and Whitelaw reported a mean ICP of 5.4 mmHg and 14.0 mmHg among those with soft and tense AF, respectively, but despite this significant difference, the authors found insufficient evidence to recommend fontanelle palpation in ICP assessment. Of interest also is that Wellons et al. also observed a high inter-observer reliability among neurosurgeons in their assessment of bulging fontanelle in preterm babies. These studies give a critical insight into the varying views about the use of fontanometry and the possible difficulties of a unified position on fontanelle tension as a means of assessing ICP. Our study has also shown such a clear-cut ICP trend as the fontanelle tension increases but despite this, it falls short of the threshold for absolute recommendation as a stand-alone means of ICP assessment.
There are limitations to study. Despite efforts standardise fontanometry findings, it is difficult to eliminate some subjective elements of the examination. In addition, this is a single hospital-based study that is limited by a relatively small sample size.
| Conclusion|| |
As standard invasive means of measuring ICP has remained out of reach or at best unsuitable for evaluation of children with hydrocephalus, this study has attempted to highlight the role of palpation anterior fontanometry which is a cheap, readily available, teachable technique with no side effects. Although the ICP increases as fontanelle tension increases, the examination is not fool-proof, and the evidence is not conclusive from this study. However, the finding of a tense AF in children with hydrocephalus must be taken seriously as an indirect adjunct to ICP assessment. Further studies with a higher sample size would perhaps be required to ascertain the correlation between AF tension and ICP in early childhood hydrocephalus.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]