Drop attacks: an unexpected diagnosis

Description

A healthy 40-year-old woman, without previous medication presented with 6-month history of recurrent falls, with no prodromes or triggering factor, loss of consciousness and with instantaneous recovery to baseline status. Physical examination, blood tests, ECG and echocardiography, EEG were unrevealing. CT of the brain showed a giant cystic lesion of the posterior fossa with mass effect and shaping of fourth ventricle and cisterns of the base (figure 1A). MRI revealed a lesion with an identical signal to the cerebrospinal fluid with no abnormal enhancement after gadolinium injection, suggesting invaginated arachnoid cyst (figure 1B,C). Patient underwent craniotomy and cyst fenestration to the magna cistern (figure 2). It was a successful surgery which permitted a gain in quality of life because no further falls were seen.

Figure 1.

CT of the brain showed a giant cystic lesion of the posterior fossa with mass effect and shaping of fourth ventricle and basal cisterns (A—axial view). MRI revealed lesion with an identical signal to cerebrospinal fluid (B—axial view and C—sagittal view) with no abnormal reinforcements after gadolinium injection, suggesting invaginated arachnoid.

Figure 2.

Control CT after surgery showed a persistent but smaller lesion with a considerable reduction of mass effect.

Drop attacks consist of sudden falls like described above. This clinical picture is more frequent in elderly individuals and idiopathic in 65% of cases. It is usually explained by a transient bilateral disorder involving structures of the central nervous system responsible for postural tonus and balance. However, over time the term ‘drop attacks’ was applied to different situations associated with fall without meeting the defining criteria noted above (syncope, arrhythmias, vasovagal responses, transient ischaemia of the vertebrobasilar area, epileptic variants, Tumarkin otolithic crises, psychiatric disorders, etc). These ones must be assumed as possible differential diagnoses.^1–3 The treatment must be individualised. In this case we have a middle-age patient with a median lesion of posterior fossa implicated in a transient blocking of the circulatory cerebral aqueduct.

Learning points.

• Drop attacks consist of sudden falls without prodromes, trigger factors or loss of consciousness and with instantaneous recovery to baseline status.

• They are usually explained by a transient bilateral disorder involving structures of the central nervous system responsible for postural tonus and balance.

• Several differential diagnoses should be considered.