Purpose Since the first description of the Arnold Chiari malformation by Hans Chiari in 1890 the understanding of this entity has improved. However, multiple aspects, including the wide variety of clinical signs and symptoms of this malformation, are not completely understood. We present a patient with an Arnold Chiari I malformation with symptoms of unilateral abducens palsy, hemiataxia and drop attacks. This patient illustrates the complexity of the diagnosis and treatment of the Arnold Chiari I Malformation.

Case report A 14 year old Moroccan boy presented with recent history of progressive frontal headache, diplopia, photo and phonophobia and drop attacks. There was a history of migraine attacks for 2 years and the patient used sumatriptan during these attacks. Physical examination revealed unilateral abducens paresis on the left side and a mild ataxia of his left leg (dysmetric and atactic heel to knee movement). There were no other neurological signs. A MRI scan of the brain showed an Arnold Chiari I malformation without syringohydromyelia. At this time surgery was not performed but is still under discussion. The patient was treated with pizotifenmaleate for his frequent migraine attacks. One month later his migraine symptoms had almost disappeared. On physical examination the clinical signs consistent with the Arnold Chiari type I malformation persisted.

Conclusion The clinical manifestations of Arnold Chiari are multiple and complex. The standard treatment of this entity is foramen magnum decompression surgery. The concomitant migraine and unilateral abducens palsy presented in this case are not described previously.