Chapter 024. Gait and Balance Disorders (Part 4)

Neuromuscular DiseasePatients with neuromuscular disease often have an abnormal gait, occasionally as a presenting feature. With distal weakness (peripheral neuropathy) the step height is increased to compensate for foot drop, and the sole of the foot may slap on the floor during weight acceptance. Neuropathy may be associated with a degree of sensory imbalance, as described above. Patients with myopathy or muscular dystrophy more typically exhibit proximal weakness. Weakness of the hip girdle may result in a degree of excess pelvic sway during locomotion.Toxic and Metabolic DisordersAlcohol intoxication is the most common cause of acute walking difficulty. Chronic toxicity...
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Chapter 024. Gait and Balance Disorders (Part 4) Chapter 024. Gait and Balance Disorders (Part 4) Neuromuscular Disease Patients with neuromuscular disease often have an abnormal gait,occasionally as a presenting feature. With distal weakness (peripheral neuropathy)the step height is increased to compensate for foot drop, and the sole of the footmay slap on the floor during weight acceptance. Neuropathy may be associatedwith a degree of sensory imbalance, as described above. Patients with myopathy ormuscular dystrophy more typically exhibit proximal weakness. Weakness of thehip girdle may result in a degree of excess pelvic sway during locomotion. Toxic and Metabolic Disorders Alcohol intoxication is the most common cause of acute walking difficulty.Chronic toxicity from medications and metabolic disturbances can impair motorfunction and gait. Mental status changes may be present, and examination mayreveal asterixis or myoclonus. Static equilibrium is disturbed, and such patients areeasily thrown off balance. Disequilibrium is particularly evident in patients withchronic renal disease and those with hepatic failure, in whom asterixis may impairpostural support. Sedative drugs, especially neuroleptics and long-actingbenzodiazepines, affect postural control and increase the risk for falls. Thesedisorders are important to recognize because they are often treatable. Psychogenic Gait Disorder Psychogenic disorders are common in outpatient practice, and thepresentation often involves gait. Some patients with extreme anxiety or phobiawalk with exaggerated caution with abduction of the arms, as if walking on ice.This inappropriately overcautious gait differs in degree from the gait of the patientwho is insecure and making adjustments for imbalance. Depressed patients exhibitprimarily slowness, a manifestation of psychomotor retardation, and lack ofpurpose in their stride. Hysterical gait disorders are among the most spectacularencountered. Odd gyrations of posture with wastage of muscular energy (astasia-abasia), extreme slow motion, and dramatic fluctuations over time may beobserved in patients with somatoform disorders and conversion reaction. Approach to the Patient: Slowly Progressive Disorder of Gait When reviewing the history it is helpful to inquire about the onset andprogression of disability. Initial awareness of an unsteady gait often follows a fall.Stepwise evolution or sudden progression suggest vascular disease. Gait disordermay be associated with urinary urgency and incontinence, particularly in patientswith cervical spine disease or hydrocephalus. It is always important to review theuse of alcohol and medications that affect gait and balance. Information onlocalization derived from the neurologic examination can be helpful to narrow thelist of possible diagnoses. Gait observation provides an immediate sense of the patients degree ofdisability. Characteristic patterns of abnormality are sometimes observed, thoughfailing gaits often look fundamentally similar. Cadence (steps/min), velocity, andstride length can be recorded by timing a patient over a fixed distance. Watchingthe patient get out of a chair provides a good functional assessment of balance. Brain imaging studies may be informative in patients with an undiagnoseddisorder of gait. MRI is sensitive for cerebral lesions of vascular or demyelinatingdisease and is a good screening test for occult hydrocephalus. Patients withrecurrent falls are at risk for subdural hematoma. Many elderly patients with gaitand balance difficulty have white matter abnormalities in the periventricularregion and centrum semiovale. While these lesions may be an incidental finding, asubstantial burden of white matter disease will ultimately impact cerebral controlof locomotion. Disorders of Balance Balance is the ability to maintain equilibrium: a state in which opposingphysical forces cancel. In physiology, this is taken to mean the ability of theorganism to control the center of mass with respect to gravity and the supportsurface. In reality, no one is aware of what or where the center of mass is, buteveryone, including gymnasts, figure skaters, and platform divers, move so as tomanage it. Imbalance implies a disturbance of equilibrium. Disorders of balancepresent with difficulty maintaining posture standing and walking and with asubjective sense of disequilibrium, a form of dizziness. The cerebellum and vestibular system organize antigravity responsesneeded to maintain the upright posture. As reviewed above, these responses arephysiologically complex, and the anatomic representation is not well understood.Failure, resulting in disequilibrium, can occur at several levels: cerebellar,vestibular, somatosensory, and higher level disequilibrium. Patients withhereditary ataxia or alcoholic cerebellar degeneration do not generally complain ofdizziness, but balance is visibly impaired. Neurologic examination will reveal avariety of cerebellar signs. Postural compensation may prevent falls early on, butfalls inevitably occur with disease progression. The progression of aneurodegenerative ataxia is often measured by the number of years to loss ofstable ambulation. Vestibular disorders have symptoms and signs in threecategories: vertigo, the subjective appreciation or illusion of movement;nystagmus, a vestibulo-oculomotor sign; and poor balance, an impairment ofvestibulo-spinal function. Not every patient has all manifestations. Patients withvestibular deficits related to ototoxic drugs may lack vertigo or obviousnystagmus, but balance is impaired on standing and walking, and the patientcannot navigate in the dark. Laboratory testing ...