Chapter 3 Falls and Drop Attacks
Everyone occasionally loses balance and sometimes falls, but repeated and unprovoked falls signal a potentially serious neurological problem. Considering the large number of potential etiologies, it is helpful to determine whether a patient has suffered a drop attack or an accidental fall. The term drop attack describes a sudden fall occurring without warning that may or may not be associated with loss of consciousness. Falls, on the other hand, reflect an inability to remain upright during a postural challenge. This most commonly affects individuals with chronic neurological impairment. When associated with loss of consciousness, drop attacks are likely due to a syncopal or epileptic event. Patients with preserved consciousness during a drop attack may harbor midline tumors in the third ventricle or in the posterior fossa. Transient ischemic attacks (TIAs) involving the posterior circulation or the anterior cerebral artery distribution can manifest in the same monosymptomatic manner. Narcoleptics experience cataplexy, and patients with Meniere disease may fall abruptly as a result of otolith dysfunction. Patients with lower-extremity weakness, spasticity, rigidity, sensory loss, or ataxia frequently fall. Middle-aged women may fall with no discernible cause. Finally, the elderly, with their inevitable infirmities, fall frequently and with potentially disastrous consequences. These associations permit a classification of falls and drop attacks, presented in Box 3.1.
Has the patient fallen before?
Did the patient lose consciousness? If so, for how long?
Did lightheadedness or palpitations precede the event?
Has the patient had excessive daytime sleepiness?
Does the patient have headaches or migraine attacks associated with weakness?
Does the patient have vascular risk factors, and were there previous symptoms suggestive of TIAs?
Are there symptoms of sensory loss, limb weakness, or stiffness?
Is there a history of visual impairment, hearing loss, vertigo, or tinnitus?
Loss of Consciousness
Syncope
The manifestations and causes of syncope are described in Chapter 2. Severe ventricular arrhythmias and hypotension lead to cephalic ischemia and falling. With sudden-onset third-degree heart block (Stokes-Adams attack), the patient loses consciousness and falls without warning. Less severe causes of decreased cardiac output, such as bradyarrhythmias or tachyarrhythmias, are associated with a prodromal sensation of faintness before the loss of consciousness. Elderly patients with cardioinhibitory sinus syndrome (“sick sinus syndrome”), however, often describe dizziness and falling rather than faintness, because of amnesia for the syncopal event. Thus, the history alone may not reveal the cardiovascular etiology of the fall. By contrast, cerebral hypoperfusion due to peripheral loss of vascular tone usually is associated with a presyncopal syndrome of progressive lightheadedness, faintness, dimming of vision, and “rubbery”-feeling legs. But even in the context of positive tilt table testing, up to 37% of patients report a clinically misleading symptom of true vertigo (Newman-Toker et al., 2008). So-called “cardiogenic vertigo” and downbeat nystagmus may also occur with asystole (Choi et al., 2010).
Orthostatic hypotension conveys a markedly increased risk of falling in the elderly and is particularly problematic in frail persons with additional risk factors for falling (Mussi et al., 2009) (see “Aged State” later in this chapter). Sudden drops in young persons, particularly when engaged in athletic activities, suggest a cardiac etiology. Exertional syncope requires a detailed cardiac evaluation to rule out valvular disease, right ventricular dysplasia, and other cardiomyopathies.
Seizures
In children and adolescents with a history of drop attacks, a tilt-table test should be considered to avoid overdiagnosing epilepsy (Sabri et al., 2006). True epileptic drop attacks in young patients with severe childhood epilepsies may respond favorably to callosotomy (Sunaga, Shimizu, and Sugano, 2009). Falling as a consequence of the tonic axial component of startle-induced seizures may be controllable with lamotrigine. Paradoxically, some antiseizure drugs can precipitate drop attacks, such as carbamazepine in rolandic epilepsy.
Transient Ischemic Attacks
Anterior Cerebral Artery Ischemia
Anterior cerebral artery ischemia causes drop attacks by impairing perfusion of the parasagittal premotor and motor cortex controlling the lower extremities. Origination of both anterior cerebral arteries from the same root occurs in approximately 20% of the population and predisposes to ischemic drop attacks from a single embolus. Paraparesis and even tetraparesis can result from simultaneous infarctions in bilateral ACA territories (Kang and Kim, 2008).
Third Ventricular and Posterior Fossa Tumors
Drop attacks can be a manifestation of colloid cysts of the third ventricle, Chiari malformation (“Chiari drop attack”), or mass lesions within the posterior fossa. With colloid cysts, unprovoked falling is the second most common symptom, after position-induced headaches. This history may be the only clinical clue to the diagnosis because the neurological examination can be entirely normal. Abrupt neck flexion may precipitate drop attacks in otherwise asymptomatic patients who are harboring posterior fossa tumors. Drop attacks occur in 2% to 3% of patients with Chiari malformation. These may be associated with loss of consciousness and often resolve after decompression surgery (Straus et al., 2009). Drops induced by rapid head turning were considered pathognomonic of cysticercosis of the fourth ventricle in the early 20th century (Brun sign). Other intracranial mass lesions such as parasagittal meningiomas, foramen magnum tumors, or subdural hematomas can also be associated with sudden drops. However, baseline abnormalities of gait and motor functions coexist, and falling may occur consequent to these impairments rather than to acute loss of muscle tone.
