Downbeat nystagmus and progressive ataxia in adults: consider Chiari malformation type 1

Nistagmo downbeat e ataxia progressiva em adultos: considere malformação de Chiari tipo 1

Downbeat nystagmus (DBN) is present in between 4 and 6% of patients with Chiari malformation type 1 (CM1). It is present in primary gaze and is characterized by a pathological phase which drifts the eyes in the upward direction followed by a downward quick-phase.¹–³ Chiari malformation type 1 is one of the most prevalent craniocervical junction abnormalities⁴ and is more frequent in Northeastern Brazilians, due to pre-historic ancestors (previously thought to be caused by the Dutch colonization).⁵ The herniation of cerebellar tonsils through the foramen magnum is radiologically characterized by the distance between the apex of the odontoid and Chamberlain line of at least 5 mm.⁶

We present a four-case series of CM1 patients who developed progressive cerebellar ataxia and DBN. Brain magnetic resonance imaging (MRI) revealed the abnormal projected cerebellar tonsils. Evaluation of the posterior fossa through brain imaging looking for structural abnormalities such as CM1 is mandatory in cases of progressive ataxia combined with DBN, headache, and pyramidal signs (Video 1 and Fig. 1).

Figure 1
(Case A-D) Cranio-cervical MRI showing Chiari malformation type 1 in the four patients with progressive ataxia and downbeat nystagmus, which is defined by herniation of cerebellar tonsils through the foramen magnum (located at least 5 mm below this structure) (arrows).

Video 1
Video of the patients with progressive ataxia and downbeat nystagmus related to Chiari malformation type 1. Online content including video sequences viewable at: https://www.thieme-connect.com/products/ejournals/html/10.1055/s-0043-1771171.

Note

• The patients have consented with the publication of the manuscript and its accompanying figures and videos.

References

• ¹
  Milhorat TH, Chou MW, Trinidad EM, et al. Chiari I malformation redefined: clinical and radiographic findings for 364 symptomatic patients. Neurosurgery 1999;44(05):1005–1017
• ²
  Wagner JN, Glaser M, Brandt T, Strupp M. Downbeat nystagmus: aetiology and comorbidity in 117 patients. J Neurol Neurosurg Psychiatry 2008;79(06):672–677
• ³
  Joaquim AF. Severe Cerebellar Degeneration and Chiari I Malformation - Speculative pathophysiology based on a systematic review. Rev Assoc Med Bras 2020;66(03):375–379
• ⁴
  Fernández AA, Guerrero AI, Martínez MI, et al. Malformations of the craniocervical junction (Chiari type I and syringomyelia: classification, diagnosis and treatment). BMC Musculoskelet Disord 2009;10(Suppl 1, Suppl 1)S1
• ⁵
  Carvalho A, Bertholdo DB. Craniocervical junction abnormalities in northeast Brazilian population. Arq Neuropsiquiatr 2017;75 (07):410–411
• ⁶
  Frade HC, França CCNL, Nascimento JJCD, Holanda MMA, Silva EJD, Araújo SA. Cranio-vertebral transition assessment by magnetic resonance imaging in a sample of a northeast Brazilian population. Arq Neuropsiquiatr 2017;75(07):419–423

Publication Dates

• Publication in this collection
  01 Dec 2023
• Date of issue
  2023

History

• Received
  23 Dec 2022
• Reviewed
  23 Feb 2023
• Accepted
  16 Mar 2023