Evaluation of dizziness / drop attacks

A drop attack is described as sudden leg weakness causing a fall without loss of consciousness. It is listed as one of the causes of falls in older persons, alongside accidents, syncope and dizziness/vertigo.

Drop attacks are often attributed to vertebrobasilar insufficiency and are often precipitated by a change in head position.

Only a small proportion of older people who fall have truly had a drop attack. The underlying pathophysiology is poorly understood, and care should be taken to rule out other causes.

Vertebrobasilar insufficiency and mechanical compression of the vertebral arteries by cervical osteophytes when the head is turned are both poorly documented, probably over-diagnosed, and should not be used as the cause of a fall simply because nothing else can be found. This is a high-yield examination statement.

The essential distinction is: syncope = sudden loss of consciousness; drop attack = sudden fall with preserved consciousness; seizure = loss of consciousness with abnormal motor activity, often with incontinence and a post-ictal phase.

Vertebrobasilar ischaemia and posterior circulation TIA — but the diagnosis of a posterior circulation TIA requires one or more other symptoms (visual field cut, dysarthria, ataxia, limb weakness, which can be bilateral) in association with vertigo; transient vertigo alone is not sufficient.

Carotid sinus hypersensitivity — a treatable cause of unexplained falls, often precipitated by head turning, in which the patient may deny loss of consciousness.

Cardiac — transient arrhythmia, heart block, aortic stenosis, causing near-syncope with a fall.

Otolithic crisis of Tumarkin in Menière’s disease supplementary — sudden violent falls without loss of consciousness. Pathy notes that in BPPV too, attacks are very sudden and may cause a drop to the ground.

Neurological — atonic (astatic) seizure; normal-pressure hydrocephalus; cervical or lumbar spondylosis with cord or root compression; cerebellar disease; Parkinson’s disease with freezing; cataplexy associated with narcolepsy supplementary ; and subclavian steal syndrome.

Musculoskeletal — sudden knee buckling from quadriceps weakness or arthritis, which patients frequently describe as a drop attack.

Step 1: Characterise the event. Was consciousness lost? Was there an aura, incontinence, tongue biting or a post-ictal phase? Could a witness confirm loss of consciousness? What is remembered immediately after? Could the patient get up, and how long did it take?

Step 2: Establish the trigger. Relationship to change of posture, turning of the head, cough, micturition, a meal, or drug intake. Note location, time of day, activity and whether alone.

Step 3: Search for premonitory symptoms — light-headedness, dizziness, vertigo, palpitations, chest pain, breathlessness, sudden focal neurological symptoms.

Step 4: Vital signs and postural blood pressure supine, sitting, and at 1 and 3 minutes standing; look for fever, tachypnoea, tachycardia and hypotension indicating acute illness.

Step 5: Targeted bedside tests — carotid sinus massage for 5 seconds under monitoring if the history suggests it; Dix-Hallpike manoeuvre; head impulse test; Romberg and eyes-closed gait testing; cardiovascular examination for arrhythmia and aortic stenosis.

Step 6: Neurological and musculoskeletal examination — mental status, focal signs, muscle weakness, rigidity or spasticity, peripheral neuropathy with posterior column signs, cerebellar tests (heel-shin, heel tapping), parkinsonian signs; and examine the feet and footwear.

Step 7: Investigations, kept targeted. 12-lead ECG and lying/standing blood pressure are the minimum. Echocardiography in all patients with a suggestive history and a systolic murmur or a delayed carotid upstroke. Continuous cardiac monitoring only where an arrhythmia can be temporally correlated with symptoms. Non-invasive vascular studies if anterior circulation TIA is suspected. CT or MRI reserved for a high suspicion of an intracranial lesion or seizure disorder. EEG only where there is a high degree of clinical suspicion of seizure. Basic bloods: haemoglobin g/dL, glucose, sodium and potassium mEq/L, creatinine mg/dL, calcium mg/dL.

Step 8: In parallel, evaluate the dizziness itself — character, time course and associated symptoms, with the full differential of general medical, neurological and otological causes, and screen with the CGA question “do you get dizzy, or does your head spin around?” followed by postural blood pressure, Dix-Hallpike, haemoglobin and the Geriatric Depression Scale.

Step 9: Treat what you find — pacemaker for symptomatic cardio-inhibitory carotid sinus hypersensitivity; Epley for BPPV; drug withdrawal and volume repletion for orthostatic hypotension; valve surgery for aortic stenosis with syncope; shunt for normal-pressure hydrocephalus; anticonvulsants for seizure; physiotherapy, strengthening and gait retraining for musculoskeletal causes; and do not label the event vertebrobasilar insufficiency by exclusion.