The reversible impairment of behavioral variant frontotemporal brain sagging syndrome: Challenges and opportunities

Abstract

Introduction Due to loss of brain buoyancy, spontaneous spinal cerebrospinal fluid (CSF) leaks cause orthostatic headaches but also can cause symptoms indistinguishable from behavioral variant frontotemporal dementia (bvFTD) due to severe brain sagging (including the frontal and temporal lobes), as visualized on brain magnetic resonance imaging. However, the detection of these CSF leaks may require specialized spinal imaging techniques, such as digital subtraction myelography (DSM). Methods We performed DSM in the lateral decubitus position under general anesthesia in 21 consecutive patients with frontotemporal dementia brain sagging syndrome (4 women and 17 men; mean age 56.2 years [range: 31–70 years]). Results Nine patients (42.8%) were found to have a CSF‐venous fistula, a recently discovered type of CSF leak that cannot be detected on conventional spinal imaging. All nine patients underwent uneventful surgical ligation of the fistula. Complete or near‐complete and sustained resolution of bvFTD symptoms was obtained by all nine patients, accompanied by reversal of brain sagging, but in only three (25.0%) of the twelve patients in whom no CSF‐venous fistula could be detected ( P = 0.0011), and who were treated with non‐targeted therapies. Discussion Concerns about a spinal CSF leak should not be dismissed in patients with frontotemporal brain sagging syndrome, even when conventional spinal imaging is normal. However, even with this specialized imaging the source of the loss of spinal CSF remains elusive in more than half of patients.

Brain Sagging Dementia

“…However, it is worth noting that the case reported by Hong et al is often wrongly referred to as the first report on this condition [ 20 ]. In the past decade, and particularly in recent years, an increasing number of reports and publications have been associated with BSD, leading to a greater recognition, understanding, and diagnosis of this condition [ 1 ••, 3 , 4 ••, 5 – 7 ].…”

“…The annual incidence of SIH is estimated at 5 cases per 100,000 individuals [ 21 ]. The occurrence of BSD remains unknown, but recent evidence suggests the disease to be more prevalent than previously recognized [ 1 ••, 3 , 4 ••, 5 – 7 , 8 •]. This increased awareness and recognition of BSD mirror the trajectory of SIH, which was also initially considered a rare disorder [ 22 ].…”

“…A third theory involves associated hypometabolism in the frontotemporal cortical region, which was illustrated by positron emission tomography (PET) in a study by Schievink et al involving approximately three-fourths of BSD patients [ 3 , 6 ]. The brain sagging and associated behavioral and cognitive changes improved following intrathecal infusion of saline [ 3 , 4 ••].…”

“…Spinal diverticula ( type 2 CSF leak ) [ 38 ], spondylotic spurs, calcified disc herniations, and connective tissue abnormalities can all cause dural tear and CSF leak leading to BSD. In recent years, advanced diagnostic techniques such as MRI myelography and digital subtraction myelography (DSM) have identified an increasing number of CSF-venous fistulas ( type 3 CSF leak ) [ 38 ] in BSD patients [ 4 ••, 8 •]. However, despite these advancements, a CSF leak site is only localized in a minority (13%) of cases [ 2 •].…”

“…Brain sagging dementia (BSD) is a rare however devastating disorder that has recently gained increasing attention and recognition [ 1 ••, 2 •, 3 , 4 ••, 5 – 7 , 8 •, 9 ]. This disease is considered an extension of the better-recognized condition known as spontaneous intracranial hypotension (SIH) which is caused by cerebrospinal fluid (CSF) leak and hypovolemia.…”