The use of a 22to 24-gauge needle and the performance of a single clean (atraumatic) tap seemingly reduce the likelihood of a postlumbar puncture headache, as discussed in Chap. 2. A period of enforced recumbency, although widely practiced as a means of preventing headache, probably does not lessen its incidence (Carbaat and van Crevel). The ingestion of large volumes of fluids, the infusion of 1,000 to 2,000 mL of 5 percent glucose, and various forms of caffeine (see further on) are usually recommended, but are of uncertain benefit.
The most dependable treatment is a “blood patch” (spinal epidural injection of approximately 20 mL of the patient’s own blood). At least 75 percent of patients are thus relieved of the headache according to Safa-Tisseront and colleagues; they report that after a second injection, improvement occurs in 97 percent. Many patients have transient back or radicular pain (sciatica) following the blood patch. Curiously, the headache is often relieved almost immediately, even if the blood is injected at some distance from the original puncture (although the procedure is usually done at the same level as the previous spinal tap). Moreover, the volume of blood injected, usually about 20 mL, is not related to the chances of success. The mechanism of this rapid improvement, therefore, may not simply be the plugging of a dural leak. A number of patients fail to benefit or have only transient effects; it is then unclear whether repeating the procedure is helpful. The administration of caffeine–ergotamine preparations or intravenous caffeine may also have a salutary, although temporary, effect on the orthostatic headache. The addition of analgesic medication is required if the patient must get up to care for himself or to travel. In protracted cases, patience is called for, as most headaches will resolve in 2 weeks or less.
As to mechanism, the pain is presumed to be from tugging on cerebral veins or assuming the upright position. Panullo and colleagues also showed that there is a downward displacement of the upper brainstem and posterior fossa contents when the patient assumes the upright position; but, as pointed out in Chap. 16, only rarely are there associated signs of brain herniation, the exceptions being some of the unusual cases discussed below. Miyazawa and colleagues have proposed that hypovolemia of the CSF, rather than lowered pressure, is the cause of downward displacement of the brain and dilatation of cerebral and spinal epidural veins. They propose that the buoyancy provided by the spinal fluid is lost in these cases.
The same problem of low pressure as that which follows lumbar puncture can occur after straining, a nonhurtful fall, or for no known reason. The cardinal feature is orthostatic headache and only rarely are there other neurologic complaints, such as diplopia from sixth-nerve palsy or a self-audible bruit. In these cases, the CSF pressure is low (60 mm H2O or less) or not measurable; the fluid may contain a few mononuclear cells but is most often normal. A few cases have presented with stupor as a result of downward transtentorial displacement of the diencephalic region (Pleasure et al) or an upper cervical myelopathy caused by downward deformation and displacement of the spinal cord (Miyazaki et al).
Some surveys suggest that patients with structural disorders of connective tissue are at greater risk for spontaneous CSF leaks than others. The Marfan and Ehlers-Danlos syndrome as well as autosomal dominant polycystic kidney disease are risk factors as summarized by Schievink.