The Laryngoscope C 2013 The American Laryngological, V
Rhinological and Otological Society, Inc.
How I Do It
An Inexpensive Blue Filter for Fluorescein-Assisted Repair of Cerebrospinal Fluid Rhinorrhea Narinder P. Singh, MBBS, MS, FRACS; David N. Roberts, MBBS, BSc, FRCS
Key Words: Endoscopic, cerebrospinal fluid, rhinorrhea, cerebrospinal fluid, fluorescein, blue filter. Laryngoscope, 124:1103–1105, 2014
INTRODUCTION The endoscopic approach to the repair of cerebrospinal fluid (CSF) rhinorrhea represents a considerable advance over open approaches.1 Advantages of the endoscopic approach include a high success rate, rapid recovery and discharge, preservation of olfaction, avoidance of frontal lobe retraction, and avoidance of a craniotomy scar.2 Intraoperatively, repair cannot be attempted until the exact leak site has been definitively visualized. Often, the leak site will be obvious. Occasionally, however, the flow of CSF must be identified first, then traced back to its origin to determine the exact leak site. Minor and intermittent leaks can be extremely difficult to visualize.3 Furthermore, at the conclusion of a repair procedure, the integrity of the repair can be difficult to judge. Intraoperative identification of CSF leaks may be aided with techniques that increase the flow of CSF. These include use of the Trendelenburg position, anesthetic techniques to perform a prolonged forced inspiration, and the injection of fluid intrathecally.4 However, the most effective technique to improve leak site identification is the use of intrathecal fluorescein,3 which colors the CSF a bright yellow-green.
From the Department of Otolaryngology–Head and Neck Surgery (N.P.S.), Westmead Hospital, University of Sydney, Sydney, New South Wales, Australia; Department of Otolaryngology–Head and Neck Surgery (D.N.R.), Guy’s and St. Thomas’ NHS Foundation Trust, London, United Kingdom. Editor’s Note: This Manuscript was accepted for publication October 30, 2013. Presented at the Australian Society of Otolaryngology–Head and Neck Surgery Annual Scientific Meeting, Melbourne, Australia, 28-31 March, 2006. The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Narinder Singh, Chairman, Department of Otolaryngology–Head and Neck Surgery, Westmead Hospital, Hawkesbury Rd., Westmead, Sydney NSW 2145, Australia. E-mail: [email protected]
The fluorescent properties of fluorescein may be understood as follows: white light consists of a mixture of light of different wavelengths. When white light shines on an object, the object appears a particular color as it reflects that particular color’s wavelength. Concentrated fluorescein appears orange as it reflects orange wavelengths (585–620 nm). However, once diluted to concentrations between 0.1% and 0.0000001% and exposed to white light, fluorescein emits a yellow-green glow. This is due to fluorescein molecules undergoing excitation by the blue portion of white light at 460 to 490 nm and temporarily entering a higher energy state. As the fluorescein molecules return to their unexcited state, the absorbed energy is released, creating a yellowgreen light of 520 to 530 nm. This effect is intensified with a pure blue light source. A typical ear, nose, and throat (ENT) light source produces light of a mixture of wavelengths to create white light. Placing a blue filter in front of an ENT light source results in the transmission of light solely in the blue portion of the spectrum, as all other wavelengths are blocked by the filter. The use of a blue filter aids in the identification of very small quantities of fluorescein.4 This can be of assistance in identifying minor leak sites and in confirming the integrity of a repair at the conclusion of a procedure. When using a blue filter, the likelihood of detection is improved by direct visualization through the endoscope, rather than using a camera and monitor. A commercially produced blue filter is available (fluorescein blue filter system, part # 20 1000 32; Karl Storz GmbH & Co, Tuttlingen, Germany), for use in the identification of CSF leaks. This filter is an excellent addition to a tertiary institution, but the cost may be prohibitive for other departments. We describe a novel and inexpensive blue filter, at a cost of a few cents, for smaller departments and for hospitals in developing countries.
MATERIALS AND METHODS
DOI: 10.1002/lary.24502
Institutional review board approval was obtained.
Laryngoscope 124: May 2014
Singh and Roberts: Inexpensive Blue Filter for CSF Rhinorrhea
1103
Fig. 1. Five-millimeter discs of filter material are cut using a standard office hole punch. The filter is made from material normally used to provide colored lighting for the stage and theater. We use a filter that provides a peak of light transmission at 460 to 490 nm (Supergel Filter #74 Night Blue; Rosco Laboratories Inc., Stamford, CT). The material is designed to withstand high temperatures of around 220 C, which makes it ideal for this application. A disc of filter material approximately 5 mm in diameter is required. This can be cut out with scissors or by using a standard office hole punch (Fig. 1). The filter disc is placed between the light source and a standard Hopkins rod endoscope (Karl Storz GmbH & Co.). First, the endoscope connector is unscrewed and the filter disc placed over the exposed surface (Fig. 2). The connector is then replaced and the light lead attached. In this manner, we prepare both a 0 and 30 “blue” endoscope alongside regular “unfiltered” endoscopes. The regular endoscopes are used intraoperatively until identification of the leak site is required, at which point they are exchanged for the blue endoscopes (Fig. 3). The blue endoscopes are also used at the conclusion of the procedure to test for persistent CSF leaks at the repair margins. We have used this technique in the repair of CSF rhinorrhea since 2005. Retrospective chart review of the author’s (N.P.S.) last three cases using the filter was undertaken. Intraoperative video recordings were reviewed by two independent surgeons. The observers’ assessment of the ease of leak site identification, along with the observers’ confidence in the integrity of the surgical repair, with and without a blue filter, was recorded on a visual analogue scale (VAS). In all cases, 25 mg (0.25 mL of 10%) of intravenous fluorescein (Retinofluor; Phebra, Lane Cove, NSW, Australia) in 10 mL of CSF was injected intrathecally 30 minutes prior to the induction of general anesthesia. The intrathecal infusion was performed through a filter (Epidural Minipack System 1; Smiths Medical Australasia, Brisbane, Queensland, Australia)
Fig. 2. A filter disc is placed over the endoscope’s exposed surface and secured in place by the standard connector prior to attachment of the light lead. over a 10-minute period, and the patients monitored for adverse reactions. An institutional review board-approved consent form describing the off-label use and possible complications of intrathecally administered intravenous fluorescein was used. Patients were premedicated with 10 mg intravenous dexamethasone and 25 mg intravenous Phenergan. An additional 25 mg of fluorescein was injected intravenously in 3 mL of normal saline. In all cases, following identification, the skull base defect was repaired using an underlay septal cartilage or middle turbinate bone graft, followed by an overlay vascularized nasoseptal flap, as described by Hadad et al.5 The intrathecal catheter was left in situ as a lumbar drain for 5 days, clamped for 24 hours, then removed. Repeat lumbar puncture with measurement of opening pressure was performed after a further 24 hours to exclude benign intracranial hypertension.
RESULTS In two cases the leak site was identified at the cribriform plate. In the third case, the leak site was identified in the sphenoid sinus. There were no cases of elevated intracranial pressure. All three cases remain leak free at a mean of 14.4 months. Intraoperative video recordings were reviewed by two independent surgeons. Ease of identification of the leak site was rated as 7.7/10 6 0.5 without the blue filter
Fig. 3. Cerebrospinal fluid (CSF) rhinorrhea secondary to a meningocele in the left cribriform plate. (A) Using our blue filter the origin of the yellow-green fluorescein-stained CSF is easily identified. (B) The same image seen through an endoscope without a blue filter.
Laryngoscope 124: May 2014
1104
Singh and Roberts: Inexpensive Blue Filter for CSF Rhinorrhea
and 8.6/10 6 0.4 with the blue filter (P
Rhinological and Otological Society, Inc.
How I Do It
An Inexpensive Blue Filter for Fluorescein-Assisted Repair of Cerebrospinal Fluid Rhinorrhea Narinder P. Singh, MBBS, MS, FRACS; David N. Roberts, MBBS, BSc, FRCS
Key Words: Endoscopic, cerebrospinal fluid, rhinorrhea, cerebrospinal fluid, fluorescein, blue filter. Laryngoscope, 124:1103–1105, 2014
INTRODUCTION The endoscopic approach to the repair of cerebrospinal fluid (CSF) rhinorrhea represents a considerable advance over open approaches.1 Advantages of the endoscopic approach include a high success rate, rapid recovery and discharge, preservation of olfaction, avoidance of frontal lobe retraction, and avoidance of a craniotomy scar.2 Intraoperatively, repair cannot be attempted until the exact leak site has been definitively visualized. Often, the leak site will be obvious. Occasionally, however, the flow of CSF must be identified first, then traced back to its origin to determine the exact leak site. Minor and intermittent leaks can be extremely difficult to visualize.3 Furthermore, at the conclusion of a repair procedure, the integrity of the repair can be difficult to judge. Intraoperative identification of CSF leaks may be aided with techniques that increase the flow of CSF. These include use of the Trendelenburg position, anesthetic techniques to perform a prolonged forced inspiration, and the injection of fluid intrathecally.4 However, the most effective technique to improve leak site identification is the use of intrathecal fluorescein,3 which colors the CSF a bright yellow-green.
From the Department of Otolaryngology–Head and Neck Surgery (N.P.S.), Westmead Hospital, University of Sydney, Sydney, New South Wales, Australia; Department of Otolaryngology–Head and Neck Surgery (D.N.R.), Guy’s and St. Thomas’ NHS Foundation Trust, London, United Kingdom. Editor’s Note: This Manuscript was accepted for publication October 30, 2013. Presented at the Australian Society of Otolaryngology–Head and Neck Surgery Annual Scientific Meeting, Melbourne, Australia, 28-31 March, 2006. The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Narinder Singh, Chairman, Department of Otolaryngology–Head and Neck Surgery, Westmead Hospital, Hawkesbury Rd., Westmead, Sydney NSW 2145, Australia. E-mail: [email protected]
The fluorescent properties of fluorescein may be understood as follows: white light consists of a mixture of light of different wavelengths. When white light shines on an object, the object appears a particular color as it reflects that particular color’s wavelength. Concentrated fluorescein appears orange as it reflects orange wavelengths (585–620 nm). However, once diluted to concentrations between 0.1% and 0.0000001% and exposed to white light, fluorescein emits a yellow-green glow. This is due to fluorescein molecules undergoing excitation by the blue portion of white light at 460 to 490 nm and temporarily entering a higher energy state. As the fluorescein molecules return to their unexcited state, the absorbed energy is released, creating a yellowgreen light of 520 to 530 nm. This effect is intensified with a pure blue light source. A typical ear, nose, and throat (ENT) light source produces light of a mixture of wavelengths to create white light. Placing a blue filter in front of an ENT light source results in the transmission of light solely in the blue portion of the spectrum, as all other wavelengths are blocked by the filter. The use of a blue filter aids in the identification of very small quantities of fluorescein.4 This can be of assistance in identifying minor leak sites and in confirming the integrity of a repair at the conclusion of a procedure. When using a blue filter, the likelihood of detection is improved by direct visualization through the endoscope, rather than using a camera and monitor. A commercially produced blue filter is available (fluorescein blue filter system, part # 20 1000 32; Karl Storz GmbH & Co, Tuttlingen, Germany), for use in the identification of CSF leaks. This filter is an excellent addition to a tertiary institution, but the cost may be prohibitive for other departments. We describe a novel and inexpensive blue filter, at a cost of a few cents, for smaller departments and for hospitals in developing countries.
MATERIALS AND METHODS
DOI: 10.1002/lary.24502
Institutional review board approval was obtained.
Laryngoscope 124: May 2014
Singh and Roberts: Inexpensive Blue Filter for CSF Rhinorrhea
1103
Fig. 1. Five-millimeter discs of filter material are cut using a standard office hole punch. The filter is made from material normally used to provide colored lighting for the stage and theater. We use a filter that provides a peak of light transmission at 460 to 490 nm (Supergel Filter #74 Night Blue; Rosco Laboratories Inc., Stamford, CT). The material is designed to withstand high temperatures of around 220 C, which makes it ideal for this application. A disc of filter material approximately 5 mm in diameter is required. This can be cut out with scissors or by using a standard office hole punch (Fig. 1). The filter disc is placed between the light source and a standard Hopkins rod endoscope (Karl Storz GmbH & Co.). First, the endoscope connector is unscrewed and the filter disc placed over the exposed surface (Fig. 2). The connector is then replaced and the light lead attached. In this manner, we prepare both a 0 and 30 “blue” endoscope alongside regular “unfiltered” endoscopes. The regular endoscopes are used intraoperatively until identification of the leak site is required, at which point they are exchanged for the blue endoscopes (Fig. 3). The blue endoscopes are also used at the conclusion of the procedure to test for persistent CSF leaks at the repair margins. We have used this technique in the repair of CSF rhinorrhea since 2005. Retrospective chart review of the author’s (N.P.S.) last three cases using the filter was undertaken. Intraoperative video recordings were reviewed by two independent surgeons. The observers’ assessment of the ease of leak site identification, along with the observers’ confidence in the integrity of the surgical repair, with and without a blue filter, was recorded on a visual analogue scale (VAS). In all cases, 25 mg (0.25 mL of 10%) of intravenous fluorescein (Retinofluor; Phebra, Lane Cove, NSW, Australia) in 10 mL of CSF was injected intrathecally 30 minutes prior to the induction of general anesthesia. The intrathecal infusion was performed through a filter (Epidural Minipack System 1; Smiths Medical Australasia, Brisbane, Queensland, Australia)
Fig. 2. A filter disc is placed over the endoscope’s exposed surface and secured in place by the standard connector prior to attachment of the light lead. over a 10-minute period, and the patients monitored for adverse reactions. An institutional review board-approved consent form describing the off-label use and possible complications of intrathecally administered intravenous fluorescein was used. Patients were premedicated with 10 mg intravenous dexamethasone and 25 mg intravenous Phenergan. An additional 25 mg of fluorescein was injected intravenously in 3 mL of normal saline. In all cases, following identification, the skull base defect was repaired using an underlay septal cartilage or middle turbinate bone graft, followed by an overlay vascularized nasoseptal flap, as described by Hadad et al.5 The intrathecal catheter was left in situ as a lumbar drain for 5 days, clamped for 24 hours, then removed. Repeat lumbar puncture with measurement of opening pressure was performed after a further 24 hours to exclude benign intracranial hypertension.
RESULTS In two cases the leak site was identified at the cribriform plate. In the third case, the leak site was identified in the sphenoid sinus. There were no cases of elevated intracranial pressure. All three cases remain leak free at a mean of 14.4 months. Intraoperative video recordings were reviewed by two independent surgeons. Ease of identification of the leak site was rated as 7.7/10 6 0.5 without the blue filter
Fig. 3. Cerebrospinal fluid (CSF) rhinorrhea secondary to a meningocele in the left cribriform plate. (A) Using our blue filter the origin of the yellow-green fluorescein-stained CSF is easily identified. (B) The same image seen through an endoscope without a blue filter.
Laryngoscope 124: May 2014
1104
Singh and Roberts: Inexpensive Blue Filter for CSF Rhinorrhea
and 8.6/10 6 0.4 with the blue filter (P
