Dr.Dhrubojyoti Sarker, S18247, Dr. Tirthajit Maitra, Dr.Rajiv Kumar Gupta
Introduction:
the central retinal vein is the principle tributary for drainage of ocular venous flow. The retinal veins meet in the optic nerve head and this anatomical uniqueness provides a special clinico physiological phenomenon that is not only useful in ophthalmoscopical examination but also establishing severalpathological abnormalities. The meeting point of the two upper and lower retinal veins are the zone where we can encounter a spontaneous pulsation and the study emphasizes its clinic pathological evaluation to rule out cerebral diseases. Spontaneousvenous pulsation (SVP) is subtle, yet rhythmic contraction and dilatation that is synchronous with the cardiac cycle. Through several populations based study we came across the fact of the prevalence of SVP, which is about 90% in normal population [1]. Coming across the compelling evidence that SVP is a result of fluctuations of the pressure gradient between the intraocular and the retrolaminar cerebrospinal fluid (CSF) pressure researchers like Jacks and Miller [2] have worked to establish this clinical picture. It is well known that the pressure difference is created at the lamina cribrosa region that intraocular space and CSF are inevitably present as change in retinal vein diameter andSVP created andwhen the intracranial pressure rises it eventually leads to abolition of SVP.
It is a well-known clinical knowledge that elevated ICP precludesSVP [3]. However, the fact is not following the thumbs rule. This study is going to elaborate that how the SVP and raised ICP can represent two separate clinical scenarios to be dealt with. From our anecdotal findings it was evident that identifying SVP immediately before lumbar puncture (LP) in some patients with high ICPs suggests that this dictum is not absolute.so the aim of the study to establishing the correlation between these two entities and to establish whether the presence of SVP is a valid test to exclude raised ICP
Material and method- the study was done in a tertiary care eye center with the collaboration of department of neurosurgery, a crosssectional prospective trial was performed that included43 cases diagnosed with various neurological ailments. Institutional review board approval was obtained from the ethics committee. Study protocols were adhered to the declaration of Helsinki. Written informed consent was obtained from all the participants. Consent was obtained from near relatives orattendants if patient found to be unable to do so.Patients were selected as said above from June, 2017, to July, 2018. Although we came across several patients but the included cases were selected only when they were prepared for lumber puncture (LP) evaluation.
After selection the cases were evaluated thoroughly from ophthalmologist’s perspective. Starting from systemic and ocular history(if any) to rule out antecedent trauma, prolonged fever, epilepsy, chronic systemic drug administration, serology status, concurrent medical and surgical history and substance abuse. It was followed by general and ocular examination. As we conducted the examinations on cases who had oriented with Glasgow coma Scale (GCS) value of 15. Ocular examination was from baseline visual acuity, anterior segment evaluation by slit lamp bio microscopy, intraocular pressure(IOP) measurement by application. Ocularmollify and deviation examined. Dilated fundoscopyperformed by a single examiner (D.S) by indirect ophthalmoscopy and 78D stereoscopic view. Cases were excluded if diagnosed as glaucomatous or any type of optic neuropathy, optic neuritis, optic disc deformity, or receiving any topical medication for ocular treatment. For examining the patient cohort 2 observer were recruited who were blinded for the cause for LP and Opening pressure(OP). OP was measured in left lateral decubitus position. The cases were examined for presence of SVP before performing LP. Dilated fundoscopy by 78D done to evaluate the exit point of central retinal vessel and special emphasis given to the change of diameter of the specific vessel. We followed the classification system postulated by Hedges et al [4] as Grade 1, up to 33% change in vessel diameter; Grade 2, 33%–66% change in diameter; and Grade 3, more than 66% change in diameter. The fundoscopic examination was performed in both yes and documented as SVP present or absent. Although the opening pressure of CSF was not done by invasive manometry it was assumed that OP if <30 mm of Hg is normal and > 30 mm of Hg is considered high.
Observation and result:
Out of the 43 cases, 25 were female and 18 male. The mean age of presentation was 42.71± 7.32 years. (range 22- 74). the mean duration of hospital stay was 11.8 days.
All the patients were examined by a single examiner (DS) and assisted neurological evaluation by senior colleague. We also documented the time interval between the examination and LP being done. The median time interval recorded was 53.4 minutes (range 15- 75 minutes). The indications of LP were the following, -persistent headache (19 patients), possible central nervous system (CNS) inflammation like multiple sclerosis (12 patients), peripheral nervous system symptoms, including GB syndrome, acute transverse myelitis (9 patients), and other CNS symptoms which included focal signs and sensory components also(3 cases)
The observation shows that SVP per patient. SVP was considered present if it was observed in at least 1 eye. Results of each SVP observed are summarized and found that out of 43 patients 31 had opening pressure(OP) < 30 mm of Hg, among them 24(77.41%) had SVP. On the other side 12 patients had opening pressure > 30 mm of Hg and 8(66.6%) had SVP.
Analyzing the Sensitivity (95% confidence interval), that is, how likely the presence of SVP was indicative of normal ICP, was 0.77 (0.72–0.82). Positive predictive value (PPV), that is, the proportion of patients with SVP who have normal ICP, was 0.75 (0.71–0.79). Specificity, that is, how likely is the absence of SVP indicative of increased ICP, was 0.35 (0.10–0.43). Negative predictive value, that is, the proportion of patients with absent SVP who have high ICP, was 0.36 (0.09–0.4).
Discussion:
The study has tried to brave the long established hypothesis –SVP if present that refutes the possibility of raised intracranial pressure(ICP). It was conducted in a simple manner with comprehensive approach by evaluating each patient from pertinent history and duly performed ophthalmological tests. The disc and SVP were stereoscopically evaluated. To establish the study we have gone through the previous researchesand found the consensus that SVP is usually abolished when the ICT reaches beyond 20 mm of H2O. keeping in front the notion we established 30 mm of H2O the point on which the SVP criteria was adjudged. It is quite obvious that ICT as well as SVP are dependable on the decubitus of the patient on which the ICT was measured or LP performed. In the previous studies the patients were examined in recumbent position. But in our study we followed the upright posture for ophthalmic examination and doing LP later. This was done to minimize the physiological upshot of ICT which is lower in upright position than supine position [5]as it is quite obvious from the physiology that when the patient s in supine posture the ICT may shoot and subsequently SVP may be lost on the contrary it is the SVP which may appear when the same patient gets upright from supine position. So if any studies to be done on the ICT it is mandatory to establish the posture first which this study did.
In our study, the proportion of patients with normal ICP was more than those with high ICP. In statistical terms, this would affect the PPV (i.e., patients with SVP and normal ICP/all patients with SVP observed) but not the sensitivity (i.e. Patients with SVP and normal ICP/all patients with normal ICP).
Our results demonstrated a low specificity and negative predictive value to this test, that is, the absence of SVP is not a helpful clinical sign. This is in keeping with the previous observations that SVP may be absent in up to 40% of patients with normal ICP. The absence of SVP should not be relied upon to indicate high ICP. One potential confounding factor is that ICP fluctuates throughout the day (9). We believe that the time interval from ophthalmoscopy to LP in our study was close enough to avoid this confounding factor.
A number of factors might be evaluated in future studies to further investigate the relativity of SVP and ICP. Recording the intraocular pressure and a description of anatomic variations of retinal veins may influence the visibility of SVP . Correlation of the ICP with SVP grading and examination in both the supine and sitting position would add important information. Use of newer technologies such as video and time-lapse photography might affect both detection and grading of SVP. Finally, a larger number of observers would improve the statistical strength and assessment of inter observer reliability. In conclusion, the presence of SVP as a clinical sign to exclude raised ICP should be used with caution. We have shown that although the sensitivity and PPV of this clinical sign is high, it is not absolute, and patients with increased ICP could be missed if this clinical sign was solely relied upon.
Conflict of interest –NIL
Financial disclosure –NIL
References:
- Levin B. The clinical significance of spontaneous pulsations of the retinal vein. Arch Neurol. 1978;35:37–40.
- Jacks A, Miller N. Spontaneous retinal venous pulsation: aetiology and significance. J NeurolNeurosurg Psychiatry. 2003;74:7–9.
- Walsh T. Spontaneous Venous Pulse. Neuro-ophthalmology: Clinical Signs and Symptoms. Philadephia, PA: Lea &Febiger, 1992:25.
- Hedges TJ, Baron E, Hedges TI, Sinclair S. The retinal venous pulsation. Ophthalmology. 1994;101:542–547.
- Gomes J, Bhardwaj A. Normal intracranial pressure physiology. In: Irani D, ed. Cerebrospinal Fluid in Clinical Practice. Philadephia, PA: Elsevier Saunders, 2009;19–25.
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