Case Report: Arnold-Chiari malformation presenting with recurrent syncope attacks
presented by Burcu Gökçe and Kemal Erdemoğlu
A 39-year-old, right-handed male presented to our outpatient clinic reporting daily occipital headache associated with recurrent syncope over a period of 2 years. His medical history was unremarkable and he took no medication on a regular basis. The patient had a normal neurological examination. His blood pressure was 120/70; his pulse rate was 70. Changes in both were physiologic when he went from supine to upright position. The patient was admitted for electroencephalogram (EEG), no epileptiform abnormalities were seen and his EEG remained normal in the later follow-ups (Figure 1). The cardiac evaluation included echocardiography, and a 24 hour Holter recording were both normal. A Doppler examination of extracranial and intracranial arteries, routine blood tests, thyroid function tests and vitamin B12 levels were also normal. Brain magnetic resonance imaging (MRI) showed a Chiari type I malformation with tonsillar herniation of 9mm below the plane of foramen magnum (Figures 2a and 2b). The patient was evaluated by neurosurgeons and decompression surgery was recommended.
- Electroencephalogram of the patient
- T1-weighted sagittal MR imaging showingthe descent of cerebellar tonsils in the foramen magnum
- T2-weighted coronal MR imaging showing the descent of cerebellar tonsils in the foramen magnum
Comment by the authors:
The Chiari type I malformation (CM1) is characterized by herniation of cerebellar tonsils to at least 3-5mm below the plane of foramen magnum. CM1 usually becomes symptomatic in adulthood and presents with some symptoms secondary to medullary distress, such as occipital headaches, sensorimotor abnormalities, and lower cranial nerve palsies (1). Rarely syncopal episodes have also been described (2).
Various pathophysiological mechanisms such as compression of the midbrain ascending reticular system, or vascular compromise (vertebrobasilar artery compression, hypotension secondary to cardiorespiratory center compression) have been proposed, although the exact cause of CM1 related syncope is still not well understood (3).
During a valsalva manoeuvre, intracranial pressure increases for a while and syncopes occur secondary to vertebrobasilar artery compression (4).
A certain similarity of symptoms such as dizziness, nausea, and fatigue is seen in patients with CM1, chronic fatigue syndrome, and orthostatic intolerance (OI), leading to a debate on their possible interrelation (4,5).
According to some authors orthostatic intolerance (OI) is a syndrome characterized by dizziness, nausea, and fatigue and associated with postural tachicardia (heart rate increases by at least 30 beats per minute, in upright posture) and high concentration of plasma norepinephrine concentrations (6,7).
The same condition, in the absence of specification of norepinephrine levels, is also referred to as postural orthostatic tachycardia syndrome (POTS) (5).
POTS has been defined as a rapid (within 10 minutes) increase in heart rate by more than 30 beats per minute, or to a heart rate that exceeds 120 beats per minute. People with POTS develop symptoms whenever they are in upright position (1). The pathophysiology of OI and POTS is still unknown. The blood pressure and heart rate in our patient was always within the normal range when he went from supine to upright position.
Hindbrain compression with or without CM1 can cause the symptoms of OI and it is resolved after surgical intervention but there are not many studies to prove this hypothesis (3).
Arnold-Chiari malformations should be considered in the differential diagnosis of recurrent syncope, especially if accompanied by headache, vertigo, or transient sensory or motor symptoms in arms or legs.