Treatment
Here, the focus will be on management of spontaneous CSF leaks rather than postsurgical or post-traumatic ones. For spontaneous spinal CSF leak, a variety of treatment modalities have been tried (Table 5). The efficacy of caffeine or theophylline is unpredictable. Some patients may report benefit while others may not. Overall, no substantial improvement is to be expected. Some patients, but not most, report definite improvement with corticosteroids. When it occurs, the improvement is often partial and hardly durable. Besides, considering the potential side effects from its chronic use, corticosteroid treatment hardly seems to be a long-term solution. Traditionally, bed rest and increased fluid intake have been advocated, mainly based on long-practiced recommendations regarding post-LP headaches. Epidural saline infusion has produced marginally unpredictable results but the experience has not been extensive. It can be tried with limited expectations in some of the patients who have failed repeated EBPs and when surgery is not an option. Even then, a sustained relief would seem unlikely. Similarly, experience with epidural infusions of colloids such as dextran has been quite limited. Intrathecal infusion of fluid has been tried when urgent volume replacement has been a treatment objective, such as stupor or coma related to sinking of the brainstem. It is not difficult to predict that, as long as such infusions continue, the patients with CSF hypovolemia may note improvement. However, after cessation of infusion, a sustained improvement, although possible, would seem unlikely. With prolonged epidural and intrathecal infusions, risk of infection will be a serious consideration.
Excess use of vitamin A may cause increased intracranial pressure, and decreased blood concentration of vitamin A has been reported in "spontaneous" intracranial hypotension. Recent scant and anecdotal observations have invited attention to potential utility of vitamin A as an adjunct in the management of SIH. Further observations are needed; and indeed, if effective, the optimal dosing needs to be determined as excess use of vitamin A can cause several toxic effects.
EBP is now recognized as the treatment of choice in those patients who have not responded to the initial trial of conservative management. EBP works via two separate mechanisms: (1) the immediate effect related to volume replacement by compression of the dural sac (decreasing the volume of the container); (2) sealing of the dural defect, which may be delayed from the first one. Therefore, it is not uncommon to note an initial quick response in connection with the first mechanism, recurrence of symptoms within merely a day or two, and then a gradual and often variable improvement after several days. Variability is, however, substantial. The efficacy of each EBP is about 30%. A previous EBP failure should not be taken as a signal that a subsequent EBP will fail. Indeed, many patients may require more than one EBP and some have required several. At times, a cumulative effect from multiple EBPs may be noted. Similarly, a previous success will not guarantee success of a future EBP. The efficacy of EBP in post-LP headaches is far more impressive. Here, the first EBP often will cause durable relief in about 90%, and a second EBP brings relief in almost all of the remaining patients. Even in inadvertent dural tears from epidural catheterizations, the efficacy of response to EBP is superior to that of spontaneous CSF leaks. There are several reasons for this discrepancy: (1) in post-LP leaks, the EBP is typically targeted right at the site of the leak or very close to, while this is not the case with spontaneous leaks; (2) in spontaneous CSF leaks, the site of most of the leaks is at the nerve root sleeves or nerve root sleeve axilla as opposed to the post-LP where the leak site is in the posterior aspect of the dura. The site of the leak in spontaneous CSF leaks is mostly at levels above the lumbar spine where most of the epidural block patches are placed. Therefore, the odds are that many of these will be nontargeted and distant from the site of the leak. (3) The dural defect in spontaneous CSF leaks, as opposed to post-LP leak, often is not a simple hole or rent instead it is frequently a preexisting zone of attenuated dura with or without associated diverticula where an unsupported arachnoid may finally give way and ooze CSF from one or more sites. Surgical anatomical observations have clearly identified such defects in many patients who have ended up with surgery.
In one study, impressive results from lumbar EBP were reported when the patients were premedicated with acetazolamide 250 mg, at 18 hours and at 6 hours before the EBP, with the patients at 30-degree Trendelenburg position from 1 hour prior to the EBP, during the procedure, and for 24 hours after the procedure. We have not tested this protocol yet.
Sometimes, when EBPs fail, epidural injections of fibrin glue or fibrin glue followed by blood may help. We have not succeeded in the method of mixing the two together before the injection, as the mixture will have a pasty and noninjectable consistency.
Surgery in well-thought-of cases is effective and can be tried when less invasive measures (such as EBP) fail. It needs to be recognized that the findings at surgery are not always straightforward. Sometimes the surgeon may encounter extravasated CSF but may not be able to locate the exact site of the leakage. The surgeon may then proceed to pack the area with blood-soaked gel foam, muscle, etc, and hope for the best. Sometimes dural defects may be seen that have markedly attenuated and fragile borders. These may not yield to suturing and would require different reinforcing techniques. Furthermore, some patients may have CSF leaks from more than one site and at different levels. It is strongly emphasized that thorough preoperative neurodiagnostic studies should be conducted to identify the actual site of the leak before surgery is undertaken.
The fundamental purpose of the surgery in the treatment of CSF leaks is to stop the leak. Other rarely practiced surgical undertakings are expected to have a convincing rationale and more than anecdotal proof of efficacy or durability.