A Case of Spontaneous Intracranial Hypotension: The Role of Dynamic CT Myelography and Epidural Blood Patch in Diagnosis and Treatment YOGESH KUMAR, MD, KUSUM HOODA, MD, SHUO LI, MD, IAN KAROL, MD, AND GERARD J. MURO, MD
ABSTRACT – Spontaneous intracranial hypotension (SIH) most commonly results from cerebrospinal fluid (CSF) leaks in the upper spinal canal. Alterations in the equilibrium between the volumes of intracranial blood and CSF lead to compensatory dilatation of the vascular spaces, mostly on the venous side. Dynamic computerized tomogram (CT) myelography can be very helpful in diagnosing the site of a CSF leak in the spinal canal. Subsequently, the site of the leak can be sealed with epidural blood patch (EBP). Key words: Intracranial hypotension, CSF leak, CT myelography, epidural, MRI
Introduction pontaneous intracranial hypotension results in postural headache, which is worsened by a sitting or standing position, due to a gravity-aided increased CSF leak. The most common site of a leak is found in the cervical and thoracic spine, which in many cases can be localized using dynamic CT myelography, and then treated with autologous epidural blood patch.
S
Case Report A 49-year-old female presented with postural dizziness and headaches, which worsened with standing and improved when lying down. Magnetic resonance imaging (MRI) of the brain was performed which demonstrated thin bilateral subdural fluid collections and diff use thick dural enhancement suggestive of SIH (Figure 1). A subsequent MRI of the thoracic spine demonstrated a dorsal subdural fluid collection extending several vertebral segments, which again suggested intracranial hypotension (Figure 2). The site of leakage remained uncertain and therefore a dynamic CT myelography was performed. The precise site of the leakage was demonstrated arising from a Figure 1. Coronal postcontrast T1 weighted MRI shows diff use pachymeningeal thickening and enhancement (marked by arrows).
YOGESH KUMAR, MD, Assistant Attending Provisional, Diagnostic Radiology, Yale-New Haven Health System at Bridgeport Hospital, Bridgeport; KUSUM HOODA, MD, Resident, Diagnostic Radiology, Yale-New Haven Health System at Bridgeport Hospital, Bridgeport; SHUO LI, MD, Resident, Diagnostic Radiology, Yale-New Haven Health System at Bridgeport Hospital, Bridgeport; IAN KAROL, MD, Chairman, Diagnostic Radiology, Yale-New Haven Health System at Bridgeport Hospital, Bridgeport; GERARD J MURO, MD, Chief of Neuroradiology, Yale-New Haven Health System at Bridgeport Hospital, Bridgeport. Corresponding author: YOGESH KUMAR, MD,
[email protected]
VOLUME 79, NO. 9
547
Figure 2. Sagittal T2 weighted MRI of the thoracic spine shows fluid collection in the dorsal extradural space (marked by arrow).
Figure 4. Lateral fluoroscopic spot fi lm of the thoracic spine shows the needle position in the epidural space just before the epidural blood patch treatment (marked by arrow).
left dural sleeve in the midthoracic region (Figure 3). The patient was then transferred to the interventional radiology suite. An EBP was performed by injecting approximately 15 cc of autologous blood in to the epidural space at the level of the leak (Figure 4). The patient reported marked improvement of symptoms within minutes and complete improvement within two hours. The patient was discharged to home on the same day without complication.
at any age, but is most frequently seen in late-middleaged females. It frequently causes postural headaches, the etiology of which can be compared to postlumbar puncture headache. Both cases alter the hydrodynamics of the CSF space and the ability of the fluid to provide support for the brain within the cranial cavity.1 Although symptoms and signs can be suggestive of the diagnosis, MRI is helpful in confirming the diagnosis. MRI of the brain will show smooth uniform pachymeningeal uptake of contrast, slit ventricles, subdural collections of fluid, and downward sagging of the brain.2 MRI of the spine usually demonstrates spinal fluid collections, dural enhancement, dilated epidural veins, and active contrast extravasation.3 Most cases of SIH result from spontaneous CSF leaks, and the majority of these leaks occur in the dura of the spinal canal. As conservative therapy fails in many cases, localization of the actual site of the leak is very helpful in treatment planning. CT myelography has been shown effective in selective cases to demonstrate the site of a leak. CT myelography is usually performed after placing a 25-gauge spinal needle in the lumbar interspace, remote from the suspected location of CSF leak. The patient is then transferred in the left-lateral decubitus position onto the gantry of a multislice CT scanner. The standard CT technique includes five scan acquisitions obtained during and immediately after injection of 15 mL 180 mgI/mL nonionic contrast material. The first acquisition is usually in the left-lateral decubitus position during contrast injection followed by four other acquisitions after injection in left-lateral decubitus, right-lateral decubitus, supine, and prone positions.4 Dynamic CT myelography has been most
Discussion SIH due to leakage of CSF from a dural tear, has been increasingly diagnosed since the introduction of magnetic resonance imaging (MRI). SIH can occur Figure 3. Dynamic CT myelography demonstrates a contrast leak from the left lateral aspect of the thecal sac suggesting a CSF leak (marked by arrow).
548
CONNECTICUT MEDICINE, OCTOBER 2015
effective in patients who have large extradural signal fluid collections as in our case. Presence of extradural fluid collection signifies a fast CSF leak.5 However, CT myelography has been associated with increased radiation doses due to multiple acquisitions. In cases which fail to respond to conservative measures, such as bed rest and adequate hydration, EBP is the definitive treatment. The treatment consists of the injection of 15 – 20 cc of autologous blood into the epidural space at or near the site of a leak diagnosed on CT myelography. The early effect of EBP is related to dural tamponade, and the later effect results from the sealing of the leak. The success rate with each EBP in spontaneous CSF leaks and in CSF leaks following lumbar puncture is approximately 30% and 90% respectively.6 The high success rate in the treatment of CSF leaks following lumbar puncture is likely related to the smaller dural defects caused by spinal needles, while spontaneous CSF leaks are usually caused by larger dural defects or leaking meningeal diverticulum, leading to less than desirable success rates. In patients with persistent symptoms, repeat EBP treatment has been shown to improve success rates.7 Surgical repair of the dural defect may be considered in patients who do not respond to two to three EBPs, especially in cases where a focal CSF leak or structural defect is identified.6
VOLUME 79, NO. 9
Conclusion MRI is helpful in confirming the clinically suspected diagnosis of spontaneous intracranial hypotension and identifying the cases that will potentially benefit from CT myelography. CT myelography in select cases can accurately localize the site of the leak, which can then be treated successfully with epidural blood patch. 1. 2. 3. 4. 5.
6. 7.
REFERENCES Gordon N. Spontaneous intracranial hypotension. Dev Med Child Neurol. 2009;51(12):932–5. Park ES, Kim E. Spontaneous intracranial hypotension: clinical presentation, imaging features and treatment. J Korean Neurosurg Soc. 2009;45(1):1–4. Medina JH, Abrams K, Falcone S, et al. Spinal imaging findings in spontaneous intracranial hypotension. Am J Roentgenol. 2010;195(2):459–64. Luetmer PH, Mokri B. Dynamic CT myelography: a technique for localizing high-flow spinal cerebrospinal fluid leaks. Am J Neuroradiol. 2003;24(8):1711–4. Luetmer PH, Schwartz KM, Eckel LJ, et al. When should I do dynamic CT myelography? Predicting fast spinal CSF leaks in patients with spontaneous intracranial hypotension. Am J Neuroradiol. 2012;33(4):690–4. Agarwal P, Menon S, Shah R, et al. Spontaneous intracranial hypotension: Two cases including one treated with epidural blood patch. Ann Indian Acad Neurol. 2009l;12(3):179–82. Sencakova D, Mokri B, McClelland RL. The efficacy of epidural blood patch in spontaneous CSF leaks. Neurology. 2001;57(10):1921–3.
549
