Acquired Chiari malformation type I (pseudo-Chiari malformation) and intracranial hypotension: Clinical observation and literature review

   One of the complications of latent intracranial hypotension is a dystopia of the tonsils of the cerebellum, which can lead to an erroneous diagnosis of “Chiari malformation type 1”.

   The aim of the work is to pay attention to the symptoms, course and diagnosis of acquired (pseudomalformation) Chiari in intracranial hypotension syndrome.

   The work is based on clinical and neurological data and magnetic resonance imaging of the brain and spinal cord of a woman aged 28 years, obtained during dynamic observation over a number of years. At the acute onset of the disease with severe postural headache, minimal neurological symptoms, magnetic resonance imaging revealed a dynamic dystopia of the cerebellar tonsils from the plane of the large occipital foramen 15 mm below it and stable hydromyelia in the thoracic region, which inclined to the diagnosis of Chiari malformation type 1. However, flattening of the bridge, thickening of the dura mater, the tendency to rounding of the sagittal sinus, narrowing of subarachnoid spaces, basal cisterns, prolapse of the bottom of the 3^rd ventricle into the prebridge cistern indicated the possibility of intracranial hypotension caused by latent liquorrhea, which was confirmed by magnetic resonance imaging with intravenous administration of gadolinium containing contrast agent in the mode of a strongly weighted T2-three-dimensional image with inversion and weakening of fluid – revealed hidden liquorrhea at the cervical level. A diagnosis of Chiari pseudomalformation has been established, which excludes surgical intervention – decompression of the posterior cranial pit. When diagnosing Chiari malformation type 1 and detecting cerebellar tonsillar dystopia, it is always necessary to exclude Chiari pseudomalformation associated with other primary pathology, in particular, with latent cerebrospinal liquor, the consequence of which is intracranial hypotension, which has specific signs in magnetic resonance imaging, and requires a different therapeutic tactic.

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