Diffuse non-aneurysmal SAH in spontaneous intracranial hypotension: Sequela of ventral CSF leak?

Introduction

Spontaneous intracranial hypotension due to a spinal cerebrospinal fluid (CSF) leak has become a well-known cause of secondary headache (1,2). Recently, various unusual neurological syndromes have been described in patients with a chronic ventral spinal CSF leak, including superficial siderosis, an amyotrophic lateral sclerosis-like syndrome (bibrachial amyotrophy), and spontaneous spinal cord herniation (1,3–5). We now report two patients with such a chronic ventral CSF leak who suffered diffuse intracranial non-aneurysmal SAH, a previously unreported association.

Case reports

Patient 1 (Figure 1 (a)–(d))

This 49-year-old woman noted the sudden onset of a severe orthostatic generalized headache associated with neck stiffness and clogged hearing. Magnetic resonance imaging (MRI) showed brain sagging and pachymeningeal enhancement. After three months of bed rest an epidural blood patch resulted in a three-year period of symptom relief. Then, between the ages of 53 and 62 three further blood patches were performed but symptoms progressed. The patient was referred for further evaluation. Spinal MRI and digital subtraction myelography showed an extensive ventral CSF collection due to a leak at the Th4–5 level. After microsurgical repair of the ventral dural tear through a posterior transdural approach, symptoms resolved except for mild headaches, and MRI showed complete resolution of the brain and spine abnormalities.

Seventeen months after surgery, at age 63, she was found unresponsive and computed tomography (CT) showed a diffuse intracranial subarachnoid hemorrhage (SAH). Cerebral angiography (performed twice), brain and spine MRI, and magnetic resonance angiography (MRA) did not detect a source of the hemorrhage. She made an excellent recovery and headaches resolved completely.

Patient 2 (Figure 1 (e)–(i))

This 73-year-old woman was found unresponsive and CT showed a diffuse SAH. Cerebral angiography (performed twice), brain and cervical spine MRI, and brain MRA did not detect a source of the hemorrhage. MRI did show superficial siderosis. The patient underwent a craniotomy for a suspected cerebellar cavernous malformation but none was found at surgery. The patient was referred for further evaluation. Review of the spine MRI showed a ventral CSF collection at the Th3–4 level and this was confirmed by CT-myelography.

The patient’s family then stated that at age 32, the patient started complaining of a severe headache with roaring in the ears that was orthostatic, requiring her to lie down for 48-hour periods in order for her to be able to be upright for a few hours. This lasted for about four weeks and symptoms resolved. Since age 60, the patient had noted progressive gait ataxia and hearing loss, possibly due to the superficial siderosis. OPEN IN VIEWER

Figure 1.

Imaging of chronic ventral spinal CSF leaks and diffuse intracranial SAH.

The patient underwent uneventful microsurgical repair of the ventral dural tear through a posterior transdural approach.

Discussion

In this communication, we report two patients with longstanding ventral CSF leaks who suffered diffuse non-aneurysmal SAH. The pattern of the SAH was similar, with a thick subarachnoid clot suggesting an arterial source. Multiple investigations were performed but no aneurysm could be detected. Diffuse non-aneurysmal SAH differs from aneurysmal SAH and, for example, the rate of re-hemorrhage is significantly less, but outcome is significantly worse compared to the non-aneurysmal perimesencephalic variant of SAH (6,7).

The etiology of diffuse non-aneurysmal SAH is unknown. We postulate that in the presently reported patients the chronic intracranial hypotension caused arterial changes because of persistent increased transmural pressure due to low intracranial CSF pressure or because of stretching of intracranial arteries due to brain sagging. A mechanical effect of a spinal CSF leak on intracranial vasculature has been postulated previously (8). Also, a systemic connective-tissue disorder is common among patients with spontaneous intracranial hypotension and this may have contributed to an underlying vasculopathy (2,9). Such a connective-tissue disorder may explain the association of spontaneous intracranial hypotension with intracranial aneurysms (9), and indeed aneurysmal SAH has been described in patients with spontaneous intracranial hypotension (10).

In one of our patients SAH occurred after the ventral leak was successfully repaired, but the repair did not occur until 13 years after the onset of symptoms. In this context it is interesting to note that in patients with ventral spinal CSF leaks and bibrachial amyotrophy, symptoms appear to be reversible only if the CSF leak is repaired within 10 years of symptom onset (4).

If diffuse non-aneurysmal SAH and spinal CSF leaks are indeed related, it is puzzling that this has not been previously reported, especially since spine MRI often is performed in this group of SAH patients (6,11). However, ventral CSF leaks most commonly occur in the thoracic spine while MRI is generally limited to the cervical spine (6). Also, motion artifact is common in the acute phase of SAH, only limited MRI sequences are sometimes used (11), the focus is usually on vascular malformations and tumors, and the baseline frequency of chronic ventral spinal CSF leaks is probably quite low. Future studies of spinal MRI in patients with diffuse non-aneurysmal SAH and long-term follow-up of patients with chronic ventral CSF leaks will provide information as to the significance of the association.

Clinical implications

Ventral spinal cerebrospinal fluid (CSF) leaks often are chronic.

Chronic ventral spinal CSF leaks have been associated with superficial siderosis and bibrachial amyotrophy.

Patients with chronic ventral spinal CSF leaks may be at risk of diffuse non-aneurysmal subarachnoid hemorrhage (SAH).