Abstract
Introduction
Spontaneous intracranial hypotension (SIH) is a well-documented syndrome that is characterized by postural headache (1). It was described by Schaltenbrand in 1938. Recently, neuroimaging studies have disclosed unique appearances of patients with SIH which have improved diagnosis (2).
In most cases SIH resolves spontaneously in 3–4 weeks. Nevertheless, complications such as subdural haematoma or hygroma can produce severe consequences (3).
We present a case of recurrent subdural haematomas associated with spontaneous intracranial hypotension which first manifested itself as diplopia.
Case report
A 70-year-old, previously healthy, man presented with a 1-month history of diplopia and holocraneal oppressive headache. Both symptoms got worse in the upright position and improved when lying down. He had never suffered from any traumas or surgery, nor had rhinorrea or otorrea. Lumbar puncture had not been carried out previously.
On examination he was afebrile and had no meningeal signs. He had a sixth nerve palsy as the only neurological deficit.
In the diagnostic test the subsequent results were obtained. Laboratory data, including haemogram, biochemistry and serologies, were normal. A computerized tomography (CT) scan of the head disclosed no abnormality. Magnetic resonance imaging (MRI) of the brain demonstrated diffuse thickening and gadolinium enhancement of the pachymeninges as well as bilateral subdural hygromas (Figs 1 and 2). A lumbar puncture was preformed in order to confirm the SIH diagnosis and rule out infectious or tumoural disease.
A gadolinium-enhanced T1-weighted image, coronal view, demonstrated intense enhancement of supratentorial meninges and tentorium.
A gadolinium-enhanced T1-weighted image, axial view, with a diffuse enhancement of the meninges.
The cerebrospinal fluid (CSF) was clear, with 0 leucocytes/mm3, 36 mg/dL protein and 59 mg/dL glucose. Cytology and cultures were negative. The CSF pressure was 50 mm H2O.
Carcinomatous or infectious meningitis were excluded by clinical and laboratory data and the MRI finding was related to chronic CSF hypotension. A work-up for a cryptic CSF leak was carried out with a radioisotope cisternography, gammagraphy and a CT myelogram. No evidence of an intracranial CSF leak was visualized.
Strict bed-rest, analgesia and hydration resulted in improvement of the headache and diplopia after 1 month of admission. As he was symptom-free he was discharged on the 35th hospital day. Two weeks after this he came again to hospital because of persistent headache. The neurological examination revealed diminished consciousness level and gait instability. A CT without contrast disclosed bilateral subdural haematomas (Fig. 3). A resolution of his symptoms was obtained with surgery which revealed haemorrhagic collection. Four days after, headache and diplopia reappeared and a repeated CT demonstrated again subdural fluid collections on both sides. After surgical drainage, diplopia persisted for some days but then improved, as did the headache. A month after this second discharge, he suffered another recurrence of haematomas. They recurred once more, 2 months later. Both times surgical drainage was necessary. Resolution of symptoms was achieved after the final time and CT did not reveal subdural fluid collections.
Computed tomography scans without contrast infusion show obliteration of sulcy and cisterns and the presence of subdural haematomas on both sides.
Additional follow-up studies, 6 months and a year after the last surgery, revealed no neurological or RM abnormalities.
Discussion
Intracranial hypotension syndrome usually occurs as a consequence of lumbar puncture or neurosurgery. However, there is also an idiopathic or spontaneous form without antecedent event. Several authors have suggested that these cases are a result of a dural tear or leak.
The most frequent symptom is headache that is elicited or exacerbated by the upright position. It may be associated with nausea, vertigo or tinnitus, as well as photophobia and nucal rigidity. Patients can also experience diplopia as a result of sixth or third nerve palsy (4).
The spinal fluid pressure is low, 60 mm H2O or less (5). Sometimes the CSF contains an abnormal number of white blood cells or high protein or both. Increased proteins may be due to pachymeningeal vasodilation (6).
MRI features, which include dural enhancement and downward displacement of brain with incisuras or cerebellar tonsillar herniation, are so characteristic that a diagnosis of SIH may be made by MRI (7, 8). However, these changes must be differentiated from other pathologies such as meningeal carcinomatosis.
Transient unilateral or bilateral abducens or third nerve palsy is a clinical picture rarely described in SIH. In ‘Medline’ 15 cases of sixth nerve palsy and one of third nerve palsy associated to SIH have been described. Diplopia was not the initial clinical finding in any of them (9). The downward sagging of the brain secondary to low CSF pressure probably produces headache by traction of pain-sensitive structures and oculomotor nerves palsy by distortion of the nerve trunks due to displacement of the brain stem.
SIH usually resolves spontaneously within 2 weeks to several months, although subdural haematomas can complicate the clinical course. In ‘Medline’ subdural haematoma incidence is 10% (10). However, we have not found any with recurrent subdural haematomas in spite of correct surgery treatment.
In our case, SIH was diagnosed during a first episode of diplopia and headache on the basis of characteristic MRI findings and the lack of prior lumbar puncture or surgical procedure, and low CSF pressure in a lumbar puncture that was carried out. The developing of subdural haematomas occurred 1 month after diagnosis. The patient referred to the reappearance of the initial headache (as did a patient described by Sato et al., 3), which was associated with a progressive diminishing of the level of conscientiousness.
The point that makes our case different is the recurrence of the haematomas several times in spite of a correct surgical drainage.
These subdural haematomas are probably due to tears in bridging veins, produced by changes in hydrostatic forces (10).
This case report emphasizes the importance of keeping in mind that some complications such as subdural haematomas can occur, in order to diagnose and treat them properly (11).