Prior to these events , 65 % of patients had a history of headaches and only 40 % of these events were accompanied by headaches . This report expanded further the idea that these transient neurologic symptoms are reflective of migraine physiology as most patients had repetitive , similar episodes , all beginning late in life .
TMAs are transient , by definition , but can progress during the event , meaning that after they begin , the attack may change in character over the course of the episode . For example , paresthesias may march from one part of the body to the next over a few minutes . The symptoms have a “ build-up ” and evolve . A person may begin experiencing flashing lights , then a field cut , and then develop a speech disturbance with or without resolution of the field cut . The length of time of the TMA varies , but on average , most people report a duration from 5 minutes to a few hours . Some patients even experience symptoms for over 24 hours , although this is rare .
“ Late-life migraine accompaniments ” are not rare ; however , they are a diagnosis of exclusion , and other reasons for these symptoms must be explored prior to establishing the diagnosis of TMA . Other causes to consider include transient ischemic attacks ( TIAs ), seizures , subarachnoid hemorrhages ( brain hemorrhages ), vascular malformations , and brain tumors . These symptoms merit an immediate visit to a doctor or the emergency department for evaluation . “ Late-life migraine accompaniments ” are a benign condition , but other causes of these symptoms are not , and must first be excluded . Certain tests such as basic blood laboratory studies , magnetic resonance imaging ( MRI ), electroencephalography ( EEG ), and special imaging of the blood vessels in the brain and neck ( magnetic resonance or CT angiography , or carotid ultrasound ) will likely be performed to help investigate the causes of the symptoms .
There are a few hints to clinically distinguish between migraine auras and TIAs . Migraine auras tend to have a gradual build-up and evolve over time , and they may move from one body part to the other , or progress from visual to sensory to speech disturbances over a period of time . The visual aura phenomenon are often “ positive ” – involving both visual fields or moving from one side to the other and progressing over the course of minutes to an hour . By positive , it means they may flash or shimmer ( Figure 1 ).
Figure 1
They can enlarge or change size . After being positive , they can become negative with blind spots . Visual symptoms in TIAs tend to be “ negative ” from the start of the episode , meaning patients often describe complete loss of vision , mainly on one side or in one eye . This develops over seconds , may last for a few minutes , then resolve within seconds . TIAs tend not to cause the positive symptoms . TIA symptoms are abrupt , whereas migraine auras tend to be gradual in onset .
When distinguishing between sensory phenomena in aura and sensory phenomena in TIA , the distribution , time course , and repetitiveness are important . Aura tends to involve a sensation of tingling or “ pins and needles ” that may start in one part of the body and then move up that body part and sequence to another . The hands and face are most commonly affected ( this is called a “ cheirooral ” distribution ) ( Figure 2 ).
Figure 2
24 HeadWise ® | Volume 6 , Issue 2 • 2016