Movement Disorders in Brain Sagging Syndrome Due To Spontaneous Intracranial Hypotension: A Review, 2024, Abhishek Lenka et al

Abstract
Background: Spontaneous intracranial hypotension (SIH), a treatable condition that stems from spinal leakage of cerebrospinal fluid, usually presents with orthostatic headache, nausea, vomiting, dizziness, and tinnitus. A subset of patients, especially those with sagging of brain structures (“brain sagging syndrome”), develop several movement abnormalities. As SIH is treatable with epidural blood patch (EBP), movement disorders neurologists should be familiar with this syndrome.

Method: The authors performed a literature search in PubMed in July 2024 using the Boolean phrase- ((“Brain sagging”)OR(“Intracranial hypotension”))AND((((((((((“Movement disorders”)OR(“Involuntary movements”))OR(“Tremor”))OR(“Dystonia”))OR(“Chorea”))OR(“Ballismus”))OR(“Myorhythmia”))OR (“Tic”))OR(“Ataxia”))OR(“Parkinsonism”)).

Result: We tabulated 21 case reports/series that highlighted the presence of movement disorders. The most reported phenomenology is gait unsteadiness. While it usually emerges in the background of the classic SIH symptoms, rarely, patients may present with isolated gait dysfunction. Tremor is the second most reported phenomenology with postural and kinetic tremor being the common subtypes. Holmes tremor has also been reported in SIH. Other reported phenomenologies are parkinsonism, chorea, and dystonia. One study reported a unique phenomenology i.e. compulsive repetitive flexion and breath holding in 35.3% of the patients. In majority of the patients, EBP resulted in substantial clinical and radiological improvement.

Discussion: Brain sagging syndrome due to SIH may present with a wide range of movement disorders. Mechanical distortion of the posterior fossa and subcortical structures result in the emergence of such movement abnormality. SIH adds to the list of conditions that result in “treatable movement disorders.” Therefore, movement disorders neurologists should be versed with the diagnosis and clinical features of this condition.

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Why would intracranial hypotension lead to brain sagging? Unless there are actually bubbles of nitrogen collecting above the brain I cannot see any reason why it should sag. If anything it should be sucked upwards I think.

I also think it pretty unlikely that brain sagging should give rise to movement disorders, other than perhaps stiff spastic gait.

 

Are we sure this is real physiology rather than a misconception. It doesn't seem right to me. If there is no gas present how or why does the brain 'settle'? If the space normally taken by CSF is taken by venous blood why doesn't the brain float just the same?


I guess the answer must be that venous capacity is mostly on the upper surface the brain, so if CSF volume is low the brain is actually pushed down by swelling sinuses. And that wouldn't necessarily relate to low CSF pressure, just volume.

I worry with papers like this that we are seeing stories like the CCI fatigue story and the 'hEDS' story, not to mention the tethered cord story, emerging. Patients with margin radiological features, or even significant radiological features, get put into a clinical syndrome simply because of referral to centres that believe in that syndrome. The text of the posted paper is not particularly reassuring on critical rigour.

 

Couldn't gait ataxia arise from a compromised (compressed) cerebellum?

 

I am not sure the whole cerebellum would be squashed rather than the tonsils and they would need to be abnormal already to go through the foramen I would think.

And ataxia isn't usually thought of as a movement disorder, I guess.