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