Frontotemporal brain sagging syndrome (FBSS) is an uncommon presentation of spontaneous intracranial hypotension where the dominant clinical features are neuropsychiatric signs and symptoms that can be mistaken for frontotemporal lobar degeneration.
On this page:
Clinical presentation
Patients with frontotemporal brain sagging syndrome present slowly, progressively and heterogeneously with a variety of signs and symptoms.
In many, neuropsychiatric and cognitive features occur only after a period of symptoms attributable to untreated intracranial hypotension (e.g. orthostatic headache). Importantly, however, a significant proportion of patients with spontaneous intracranial hypertension do not have headaches 4. In these individuals, the diagnosis is harder to make and more closely resembles a neurodegenerative disease.
Signs and symptoms include 1-4,6:
-
headache
most often orthostatic
often preceded other symptoms but not always present
frontal dysfunction (e.g. apathy, disinhibition, poor planning)
cognitive impairment (e.g. memory disturbance)
reduced conscious state (e.g. somnolence, drowsiness, even coma)
neck pain
-
brainstem/cerebellar dysfunction
tremor
disequilibrium
cranial nerve dysfunction
auditory symptoms
compulsive repetitive flexion (at the waist) with breath-holding
In some patients the neuropsychiatric symptoms are more pronounced later in the day and may improve by lying down 4.
Only approximately half of patients will have a low CSF opening pressure (<6 cm H2O) 4.
Intrathecal infusion of preservative-free normal saline can also be performed to determine if symptoms abate 4.
Radiographic features
MRI
The MRI brain and spine features are those of spontaneous intracranial hypotension, dominated by 1,2,4:
venous engorgement
subdural effusions or subdural hematomas
-
sagging of intracranial content
reduced mamillopontine distance
effacement of the basal cisterns
slumping of the pons against the clivus
downward drooping splenium of the corpus callosum
temporal uncal herniation
spinal longitudinal epidural CSF collection (SLEC)
MRI obtained following treatment will show resolution of the aforementioned features if successful 4.
Importantly, frontotemporal atrophy is usually absent 2.
Nuclear medicine
Positron emission tomographic (PET) may show frontotemporal hypometabolism 2,4.
Treatment and prognosis
Treatment depends on identifying and treating the site of CSF leak (see spontaneous intracranial hypotension). If this is successful then substantial symptomatic improvement can be expected in many patients 4.
Unfortunately, a source of leak cannot be identified in all patients. In such cases speculative epidural blood patches can be performed. These frequently result in transient improvements, however, these are not often sustained 1,2,4. It is likely that in the past, many of these patients with unidentifiable leaks have had CSF-venous fistulas, given it is an underdiagnosed entity 3.
Other treatment options may include:
wearable epidural spinal infusion systems, may have benefit 4
oral corticosteroids, usually with underwhelming results 1,2,4
Importantly, posterior fossa decompression as performed in Chiari 1 malformations is generally not helpful as cerebellar tonsillar ectopia is a sequela of the underlying problem rather than being causative 4.
History and etymology
The first case of neuropsychiatric presentation of a patient with spontaneous intracranial hypotension was published in 2002 by Hong et al. 5, and the term frontotemporal brain sagging syndrome first proposed in 2011 by Wicklund et al. 2.
Differential diagnosis
-
frontotemporal atrophy usually present
absence of signs of spontaneous intracranial hypotension
compulsive repetitive flexion (at the waist) with breath-holding, which can occur in frontotemporal brain sagging syndrome, may be a useful clinical sign to differentiate these patients from those with behavioral variant frontotemporal lobar degeneration 6
-
absence of signs of spontaneous intracranial hypotension
Unable to process the form. Check for errors and try again.