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CASE REPORT
Year : 2023 | Volume
: 14
| Issue : 1 | Page : 108-112
Spinal dural cerebrospinal fluid fistula as a cause of spontaneous intracranial hypotension syndrome: Diagnosis and surgical treatment
Anton Konovalov1, Fyodor Grebenev1, Dmitry Asyutin1, Bahromon Zakirov1, Nikolay Konovalov1, Igor Pronin1, Shalva Eliava1, Bipin Chaurasia2
1 Burdenko Neurosurgical Center, Moscow, Russia
2 Neurosurgery Clinic, Birgunj, Nepal
Correspondence Address:
Anton Konovalov
Burdenko Neurosurgical Center, 4th Tverskaya-Yamskaya Str.,16, Moscow 125047
Russia
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/jcvjs.jcvjs_135_22
Abstract
Spontaneous intracranial hypotension (SIH) syndrome most often occurs following a cerebrospinal fluid (CSF) fistula that develops in the spinal space. Neurologists and neurosurgeons lack an understanding of the pathophysiology and diagnosis of this disease, which can make timely surgical care difficult. With the correct diagnostic algorithm, it is possible to identify the exact location of the liquor fistula in 90% of cases; subsequent microsurgical treatment can save the patient from the symptoms of intracranial hypotension and restore the ability to work. Female patient, 57 years old, was admitted with SIH syndrome. Magnetic resonance imaging (MRI) of the brain with contrast confirmed signs of intracranial hypotension. Computed tomography (CT) myelography was performed to pinpoint the location of the CSF fistula. The diagnostic algorithm and successful microsurgical treatment of a patient with spinal dural CSF fistula at the Th3-4 level using a posterolateral transdural approach. The patient was discharged on day 3 after the surgery when these complaints regressed completely. At the control examination of the patient 4 months postoperatively, there were no complaints. Identification of the cause and location of spinal the CSF fistula is a complex process that requires several stages of diagnosis. Examination of the entire back with MRI, CT myelography, or subtraction dynamic myelography is recommended. Microsurgical repair of a spinal fistula is an effective method for the treatment of SIH. The posterolateral transdural approach is effective in the repair of a spinal CSF fistula located ventrally in the thoracic spine.
Keywords: Intracranial hypotension, spinal dural cerebrospinal fluid fistula, spontaneous intracranial hypotension, surgical treatment
Introduction 
Severe headache, general weakness, dizziness, and inability to stay upright for a long time are characteristic symptoms of spontaneous intracranial hypotension (SIH) syndrome.[1],[2] SIH most often occurs following a cerebrospinal fluid (CSF) fistula that forms in the spinal space.[3] There are three types of spinal CSF fistulas: direct defect of the dura mater (DM), rupture of the radicular diverticulum, and CSF-venous fistula.[4] Epidemiologically, SIH is not a rare condition, with a prevalence of 5 per 100,000 population per year.[5],[6] However, experience in the treatment of this condition is limited to only a few clinical observations.[6] There are also no diagnostic criteria and recommendations for the treatment of patients with this pathology. The pathophysiology and diagnosis of this condition are poorly known to neurologists and neurosurgeons, which can make timely surgical care difficult. Often, with the correct diagnostic algorithm, it is possible to identify the exact location of the liquor fistula in 90%.[7] Microsurgical treatment allows the patient to get rid of the symptoms of intracranial hypotension and return to work.
The aim of this article is to describe the diagnostic algorithm and successful microsurgical treatment of a patient with spinal dural CSF fistula in the upper thoracic spine, using a posterolateral transdural approach.
Case Report Female patient, 57 years old, was admitted to our hospital with complaints of severe headaches and an inability to stay upright for a long time. Over time, the frequency and intensity of symptoms began to increase, which was the basis for the examination.
Magnetic resonance imaging (MRI) of the brain with contrast was performed, which revealed signs of intracranial hypotension [Figure 1].
Figure 1: MRI of the brain. (a) T1 in the sagittal projection, such signs of intracranial hypotension are visualized as an increase in the pituitary gland (red arrows), expansion of the sinus cavities of the DM (green arrows); (b) T1 with contrast enhancement in the sagittal projection, pachymeningeal accumulation of the contrast agent (blue arrows), enlarge pituitary gland ( red arrow) ; (c) T2 in the axial projection, bilateral subdural hygromas (yellow arrows); (d) T1 with contrast enhancement in the coronal projection, with pachymeningeal accumulation of the contrast agent (blue arrows), enlarge pituitary gland (red arrow). MRI: Magnetic resonance imaging, DM: Dura materAccounting for the absence of an intracranial basis for hypotension, we decided to perform an MRI of the spine to exclude a spinal CSF fistula [Figure 2].
Figure 2: MRI of the spine. (a) MR myelography of the cervical spine T2-WI in the sagittal projection, the red arrow indicates the DM, the white arrow indicates the presence of intra- and extradural CSF; (b) T2-WI of the cervical spine in the sagittal projection, the red arrow indicates the DM, the white arrow indicates the presence of intra- and extradural CSF; (c) MR myelography of the cervical spine in the sagittal projection, the outflow of CSF is determined extravertebral (white arrow). MRI: Magnetic resonance imaging, DM: Dura mater, CSF: Cerebrospinal fluid, T2-WI: T2-weighted imageTo pinpoint the location of the dural fistula during hospitalization, computed tomography (CT) myelography was performed [Figure 3]. Based on a body weight of 65 kg, 7 ml of the radiopaque agent “VisiPak 320,” was injected intrathecally with a lumbar puncture. As per CT myelography in the region of Th3-4 vertebrae, extradural spread of contrast agent is detected. A reexamination without contrast at this level reveals a small osteophyte.
Figure 3: CT myelography and CT of the spine without contrast. (a and b) CT myelography in axial and sagittal projections (a and c), in area of Th3-4 vertebrae, extradural spread of a contrast agent is detected (red contour); (b and d) CT scan of the spine 14 h after CT myelography without contrast, a small osteophyte was detected near the Th3-4 vertebrae (blue outline). CT: Computed tomographyThus, here the most likely cause of intracranial hypotension is a dural CSF fistula, formed due to damage of the ventral surface of the dura by an osteophyte near the Th3-Th4 vertebrae.
Surgery was performed in the prone position. Using the Medtronic Navigation System, the location of the proper vertebral level and incision was confirmed. A linear incision is made in the right paravertebral region, 4 cm long, at the level of the Th3-4 vertebrae. Intermuscular access to the intervertebral joint of the above vertebrae is performed, and localization of the Th3-4 vertebrae is respecified with neuronavigation. Part of the joint, arches, and pedicles of both vertebrae were resected, as the root and dural sac was visualized. It was noted that CSF was stained with blood leaked from the epidural space. An attempt at extradural access to the ventral surface of the dural sac ipsi-and contralaterally to visualize the fistula failed. In view of this, a linear incision of the DM was made along the lateral surface above the exit point of the root, which was taken aside on the handles. After the dissection of the odontoid ligament and mobilization of the spinal cord, the spinal cord was displaced to the right; this produced contralateral access to the ventral surface of the spinal cord. A small, ossified formation was found at the base of a linear DM defect up to 10 mm in size was found [Figure 4]. With the microsurgical instruments and technique, this formation was removed and sent for histological examination. The defect of the ventral surface of the DM was sutured with 4 single sutures with 8/0 thread. A TachoComb was placed on the intradural surface of the DM in the area of the sutured defect for the purpose of sealing. After that, the DM incision on the dorsal surface is sutured with a 6/0 thread. The DM sutures on the ventral and dorsal surfaces were additionally sealed from the outside with TachoComb and DuraSeal glue. No liquor leakage was noted.
Figure 4: Intraoperative photos. (a) on the ventral surface of the DM, after retraction of the spinal cord, an ossified formation (blue outline) perforating the DM is visualized; (b) final stage of removal of the formation, the defect of the dura mater is better visualized (green contour); (c) fully visualized linear defect of the dura mater; (d) the defect of the dura mater is sutured. DM: Dura materThe postoperative period proceeded satisfactorily, with histological examination: “Cartilage tissue with dystrophic changes.” The patient was discharged on day 3 after the surgery when these complaints regressed completely, and according to the MRI of the brain, there were signs of regression of intracranial hypotension [Figure 5]. At the control examination of the patient 4 months postoperatively, there were no complaints. The control MRI shows a positive trend, with no signs of intracranial hypotension and the absence of subdural accumulations [Figure 5].
Figure 5: Postoperative MRI of the brain. (a and c) T1-WI with contrast enhancement in the sagittal and coronal projections on day 3 after surgery; (b and d) T1-WI with contrast enhancement in the sagittal and coronal projection 4 months after surgery. On the 3rd day after the operation, in Figures a and b, signs of regression of intracranial hypotension are determined: a decrease in the intensity of accumulation of the contrast agent TMT, a slight decrease in the pituitary gland. Bilateral subdural hematomas persist in the acute-subacute stage. Four months after the operation, in addition to the above-mentioned signs, regression of subdural hematomas was noted. MRI: Magnetic resonance imaging, T1-WI: T1-weighted image Discussion The syndrome of SIH may be due to the presence of a spinal CSF fistula [Figure 6].[8],[9] Patients with severe clinical and radiographic symptoms of SIH should undergo a complete back examination to identify the location of the CSF fistula.[4] In the Russian Federation, there is no recommended protocol for examining such patients.[6] In our opinion, it is correct to use the diagnostic algorithm published by Wheeler et al. in 2016.[10] The presented algorithm allows, in most cases, to detect the location and type of spinal CSF fistula. According to the recommendations of Wheeler et al., patients with severe clinical manifestations of SIH should undergo MRI of all parts of the back in T1, T2, T2 Flair, short-TI inversion recovery (STIR) , and Fiesta, CSF Dynamics modes.[10] MRI can detect the presence of degenerative changes in the back, the presence of accumulation of CSF epidurally, and the presence of radicular diverticula and/or dilated paraspinal veins that may be associated with these diverticula.[11] In most cases, an MRI alone may not be enough. An additional study is the performance of CT myelography, which increases the chance of identifying and confirming the site of CSF leakage.[3],[12] CT myelography is performed according to a special protocol-first, CT of the entire back is performed without contrast. At the second stage, the patient undergoes a lumbar puncture and intrathecal administration of a radiopaque agent (for example, VisiPak 320, Carlstadt, NJ, USA at the rate of 1 ml/10 kg of body weight). If a ventrally located DM defect is suspected, the patient is placed in the prone position with a slight downward tilt of the body, and a CT scan of the entire back is performed.[5] If CSF leakage from a ruptured pararadicular diverticulum is suspected, the patient is placed on the side, where the diverticulum is located.[5] Without convincing evidence of CSF leakage, subtraction dynamic myelography performed in an X-ray operating room is recommended. This study detects CSF fistulas, a rare type of spinal CSF fistula.[8]
Figure 6: Schematic representation of location and pathophysiology of a dural CSF fistula. Red arrows indicate the direction of CSF outflow through the formed dura defect. CSF: Cerebrospinal fluidOnce the exact location of the fistula is established, surgical treatment achieves regression of symptoms in 90% of cases.[3],[13] Depending on the location of the fistula, the tactics of surgical treatment may be different. Fistulas of the type of direct defect of DM (type 1) with ventral location on the neck can be closed through the anterior approach.[1] Ventrally located dural fistulas in the thoracic region are difficult to operate through the anterior transthoracic approach.[14] In such situations, it is recommended to perform the most lateralized posterolateral approach. In their work, Beck et al. proposed several options for surgical approaches to CSF fistulas of the thoracic spine, depending on their type.[2] We also chose a posterolateral approach for this clinical observation, using transdural resection of the osteophyte with combined closure of the dural defect.
The advantage of this approach, in our opinion, is sufficient visualization of the ventral dura with minimal spinal cord traction. Use of anterior approaches is limited by a small, deep surgical corridor, which in most cases may require corpectomy at several levels for a microsurgical suture to the dural defect and its repair.[15]
In degenerative changes in the spine, accompanied by the occurrence of intracranial hypotension, most often the defects are located ventrally (77% of cases), posterolaterally (19%), and foramenally (4%). Anterior (ventral) perforations may be caused by osteophytes, calcified disc fragments, or thin bone fragments.[11] When using posterior approaches, the rate of successful surgical treatment of CSF fistulas is higher.[16],[17] Furthermore, in these cases, the defect of the DM could be visualized and closed. Wilson et al. described a posterolateral extradural approach with costotransversectomy at the T6-7 level, but the fistula site could not be visualized, although a ventromedial disc osteophyte was identified during the operation.[15]
It is not always possible to reliably identify the location of the CSF fistula, according to neuroimaging data. Thus, microsurgical intervention is the final stage of diagnosis and simultaneous treatment in disputed situations. As such, we recommend the use of a posterolateral transdural approach in the thoracic region, which allows us to assess the anatomy of the ventral, lateral, and posterior surfaces of the dura.
Conclusion The syndrome of SIH may be a defect in the DM against the degenerative spine process. Identification of the cause and location of spinal the CSF fistula is a complex process that requires several stages of diagnosis. Examination of the entire back with MRI, CT myelography, or subtraction dynamic myelography is recommended. Microsurgical repair of a spinal fistula is an effective method for the treatment of SIH. The posterolateral transdural approach is effective in the repair of a spinal CSF fistula located ventrally in the thoracic spine.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
References 
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