THE formation of cranial subdural hematomas after lumbar puncture is a well-known complication of spinal anesthesia, although rare in young patients. 1–3Pathogenesis of this condition has been related to rupture of bridging veins joining the cerebral surface and the dura mater. The precipitating event in these cases is the continuous leakage of cerebrospinal fluid through the dural hole. More unusual is the production of subdural hygromas in the intracranial cavity, which has not yet been described. Our aim is to describe the occurrence of a subdural hygromas complicating inadvertent lumbar puncture and to discuss the problems encountered in their diagnosis and management.
A 26-yr-old nulliparous woman presented in active labor. She had a history of migraine, but was otherwise healthy. She requested epidural analgesia. The anesthesiologist identified the L2–L3 interspace and attempted to place a catheter using an 18-gauge Tuohy needle. During placement, an accidental dural puncture was noted, and the needle was withdrawn. A subsequent puncture was performed at the L3–L4 and the epidural catheter was successfully inserted. The labor elapsed uneventfully.
Six hours after delivery, the patient began to complain of an intense, throbbing, occipital headache that worsened when she was in the upright position. There was neither neck stiffness nor fever. A tentative diagnosis of postdural puncture headache was made. Treatment consisted of bed rest, hydration, and analgesics. 4,5At this time, the patient refused a recommended epidural blood patch and, after a 3-day hospital stay, was discharged home.
Fifteen days later, the patient returned to the hospital complaining of continued severe headaches. She did not describe diplopia, tinnitus, or vomiting. Except for mild neck rigidity, her neurologic examination was normal and there was no papilloedema. The patient was again offered an epidural blood patch, which she accepted. During aseptic conditions, an epidural injection of 7 ml autologous blood was performed over 1 min. After an overnight stay at the hospital, the patient became symptom free and was discharged home.
The patient was readmitted 12 days later because her headache had returned to its original intensity after a 4-day period of pain relief. She denied being confused, experiencing vomiting, or having other neurologic symptoms. Cranial computed tomography was performed, which showed bilateral frontoparietal subdural hygromas, with gyral effacement and small ventricles (fig. 1). The patient was also studied using magnetic resonance imaging venography of the brain that ruled out thrombosis of the cerebral venous sinuses. 6Gadolinium-enhanced and -unenhanced magnetic resonance imaging of the lumbosacral spine was also obtained, 7which failed to show dural enhancement, subdural collections of fluid, or the site of the cerebrospinal fluid fistula. 8,9
A subsequent epidural blood patch was performed using 14 ml autologous blood, and adequate intravenous hydration and analgesia were administered. After this management regime, the patient's headaches decreased in severity and were controlled with the intake of mild oral analgesics. The patient was discharged from the hospital 11 days later (on day 39 postpartum). Two weeks after the second epidural blood patch, the patient was symptom free and subsequent cranial computed tomography showed complete resolution of the subdural collections (fig. 2).
The occurrence of subdural hygromas after epidural procedures may be more common than has been recognized previously. Subdural hygromas are most often the result of traumatic events, particularly head trauma. The mechanism involved is probably the continuous leakage of cerebrospinal fluid through the orifice made in the dura mater at the time of the lumbar puncture. 10,11If the brain shrinks because of brain atrophy, excessive dehydration, or decreased intracranial pressure, a subdural collection may develop by a passive effusion of fluid. Most subdural hygromas from other causes resolve when the brain is well-expanded. However, some instances of hygromas may evolve to chronic subdural hematomas if the conditions leading to their formation persist over several weeks. 10
The diagnosis of subdural hygroma can be difficult on a clinical basis alone, especially if an obvious cerebrospinal fluid leak is not reported. We performed a review of the literature in regard to subdural hygromas associated with postdural puncture headache and have not found any previous references to this condition. We suggest that the existence of a subdural hygroma should be included in the differential diagnosis of the cause of a persistent headache presenting after a dural puncture, especially if first steps of management have already failed.