Benign Paroxysmal Positional Nystagmus ROBERT W. BALOH,
M.D.,t
SUSAN M. SAKALA,$ AND VICENTE HONRUBIA, M.D.w
A characteristic nystagmus profile of benign paroxysmal positional nystagmus was determined from analyses of horizontal andvertical electro-oculographic recordings in 32 patients. The vertical component was upbeat in both eyes (fast phase toward the ground in the head-hanging position), whereas the horizontal component was dissociated with the ipsilateral eye beating away from the down ear and the contralateral eye beating toward the down ear. The amplitude of the vertical component was larger in the ipsilateral eye. This dissociated nystagmus profile is consistent with a burst of excitatory activity originating in the posterior canal of the ear that is undermost at the end of the positioning maneuver,
The pathophysiology and clinical significance of benign paroxysmal positional nystagmus have been subjects of continual controversy. The disorder is characterized by a burst of nystagmus (and associated vertigo) induced by a rapid positioning maneuver, a latency from the end of positioning to the onset of nystagmus, and diminished response (fatigue) on repeated testing. Although B~r~ny ~ described the clinical features of the disorder in 1921, benign paroxysmal positional nystagmus was not commonly recognized until the report of 100 cases by l)ix and Hallpike 2 in 1952. Despitethe general consensus that it was a self-limited disorder of the peripheral labyrinth, occasional reports of the disorder's occurring in patients with well documented nervous system lesions raised questions about the appropriateness of
the descriptive term "benign. '''>~ In some cases the "central" varieties of paroxysmal positional nystagmus had features that permitted distinction from the benign variety, whereas in others such features were not apparent, d, ~, s B~r~ny 1 concluded that benign paroxysmal positional nystagmus was caused by a lesion of the otolith organs, since it occurred in only one position and it appeared to be independent of the positioning maneuver, Dix and Hallpike ~ supported this hypothesis by finding unilateral degeneration of the utricular macula at necropsy in a typical case of benign paroxysmal positional nystagmus. Schula~echt 7 found basophilic deposits on the cupulae of the posterior canals of the left ear in two patients who manifested typical benign paroxysmal positional nystagmus in the left head-hanging position
This work was supported by NIH grant NS 09823. ~Associatc Professor, Department of Neurology, University of California, Los Angeles, School of Medicine, Los Angeles, California. *Research Associate, Department of Neurology, University of California, Los Angeles, School of Medicine, Los Angeles, California. w Department of SurgerylOtolaryngology, University of California, Los Angeles, School of Medicine, Los Angeles, California. American Iaurnal of Otolaryngology-Volume 1, Number 1, Fall 1979
1
American Journal of
Otolaryngology
2
prior to death from unrelated disease; the posterior canal cupulae of the right ears were normal in appearance. Schuknecht and Ruby s subsequently reported another identical case, and then examined 391 temporal bones from 245 individuals to assess the incidence of cupular deposits in the general population. They found small deposits in 125, medium sized deposits in 20; and large deposits in four; in none did the deposits exceed the size of those found in the three patients with benign paroxysmal positional nystagmus. Schuknecht proposed the following mechanism to explain benign paroxysmal positional nystagmus. Otoconia from a degenerating utricular macule settle on the cupula of the posterior canal, causing it to become heavker than the surrounding endolymph. When the patient moves from the sitting to the head-hanging postion (standard positioning maneuver), the posterior canal moves from an inferior to a superior position and utriculofugal displacement of the cupula occurs. The long latency before nystagmus onset reflects the period of time required for the otoconial mass to be displaced, and fatigability is caused by disbursement of particles in the endolymph. It is difficult for one to compare reports of so-called "typical" benign paroxysmal positional nystagmus, since most of them do not include recordings of the nystagmus. Whether the direction of benign paroxysmal positional nystagmus is always the same and whether paroxysmal positional nystagmus of central origin differs in direction from that of peripheral origin is not established. Benign paroxysmal positional nystagmus is usually described as being rotatory with the upper pole of the eye beating toward the undermost ear. 2 The consistency of this pattern and the amplitude of the actual horizontal and vertical components in each eye, to our knowledge, have not been reported. If, as Schuknecht suggests, benign paroxysmal positional nystagmus originates from the posterior canal of the undermost ear, it should have similar horizontal and vertical components in each patient, i.e., those predicted by the known anatomical connections between the posterior canal and the extraocular muscles. Furthermore, the profile of the slow component velocity obtained from recordings .of benign paroxysmal positional nystagmus should be helpful in understanding the dynmnics of the abnormal cupula of the posterior canal. With these practical and theoretical considerations in mind we studied electro-
oculographic recordings of benign paroxysmal positional nystagmus from 32 patients. CASE MATERIAL AND METHODS
Electro-oculographic recordings of benign paroxysmal positional nystagmus were made in 32 patients. Unilateral vertical (left eye) and bitemporal horizontal eye movements were recorded in 24 patients, and bilateral monocular horizontal and vertical eye movements were recorded in the other eight. Details of the recording system are reported elsewhere. 9 The nystagmus was induced by a rapid change from the sitting to the head-hanging-right and headhanging-left positions (as described by Dix and Hallpike2). The patient's eyes were opened behind Frenzel glasses in a darkened room. The duration of the standard position change was approximately 2 seconds. The effects of slower and more rapid positional changes were also studied. Each patient reported a typical history of brief episodes of vertigo induced by position change, and each demonstrated paroxysmal positional nystagmus that fatigued on repeated positioning. The clinical diagnoses were as follows: post-traumatic, 9; vestibulopathy of unknown cause (benign paroxysmal positional nystagmus and vestibular paresis ~ on caloric testing), 10; vertebral basilar insufficiency, 2; multiple sclerosis, 1; idiopathic (isolated), 10. The average age was 56.4---13.9 years with a range of 34 to 75 years. Post-traumatic benign paroxysmal positional nystagmus occurred in younger patients (mean age, 45--+15 years), whereas idiopathic benign paroxysmal positional nystagmus was more common in older patients (mean age, 63-+7 years). There were 19 females and 13 males. In 23 patients benign paroxysmal positional nystagmus occurred in only one head-hanging position, whereas in nine it occurred in both. In the latter patients the nystagrnus was more prominent in one position and its direction was the same in both positions. Fourteen patients had significant (p
M.D.,t
SUSAN M. SAKALA,$ AND VICENTE HONRUBIA, M.D.w
A characteristic nystagmus profile of benign paroxysmal positional nystagmus was determined from analyses of horizontal andvertical electro-oculographic recordings in 32 patients. The vertical component was upbeat in both eyes (fast phase toward the ground in the head-hanging position), whereas the horizontal component was dissociated with the ipsilateral eye beating away from the down ear and the contralateral eye beating toward the down ear. The amplitude of the vertical component was larger in the ipsilateral eye. This dissociated nystagmus profile is consistent with a burst of excitatory activity originating in the posterior canal of the ear that is undermost at the end of the positioning maneuver,
The pathophysiology and clinical significance of benign paroxysmal positional nystagmus have been subjects of continual controversy. The disorder is characterized by a burst of nystagmus (and associated vertigo) induced by a rapid positioning maneuver, a latency from the end of positioning to the onset of nystagmus, and diminished response (fatigue) on repeated testing. Although B~r~ny ~ described the clinical features of the disorder in 1921, benign paroxysmal positional nystagmus was not commonly recognized until the report of 100 cases by l)ix and Hallpike 2 in 1952. Despitethe general consensus that it was a self-limited disorder of the peripheral labyrinth, occasional reports of the disorder's occurring in patients with well documented nervous system lesions raised questions about the appropriateness of
the descriptive term "benign. '''>~ In some cases the "central" varieties of paroxysmal positional nystagmus had features that permitted distinction from the benign variety, whereas in others such features were not apparent, d, ~, s B~r~ny 1 concluded that benign paroxysmal positional nystagmus was caused by a lesion of the otolith organs, since it occurred in only one position and it appeared to be independent of the positioning maneuver, Dix and Hallpike ~ supported this hypothesis by finding unilateral degeneration of the utricular macula at necropsy in a typical case of benign paroxysmal positional nystagmus. Schula~echt 7 found basophilic deposits on the cupulae of the posterior canals of the left ear in two patients who manifested typical benign paroxysmal positional nystagmus in the left head-hanging position
This work was supported by NIH grant NS 09823. ~Associatc Professor, Department of Neurology, University of California, Los Angeles, School of Medicine, Los Angeles, California. *Research Associate, Department of Neurology, University of California, Los Angeles, School of Medicine, Los Angeles, California. w Department of SurgerylOtolaryngology, University of California, Los Angeles, School of Medicine, Los Angeles, California. American Iaurnal of Otolaryngology-Volume 1, Number 1, Fall 1979
1
American Journal of
Otolaryngology
2
prior to death from unrelated disease; the posterior canal cupulae of the right ears were normal in appearance. Schuknecht and Ruby s subsequently reported another identical case, and then examined 391 temporal bones from 245 individuals to assess the incidence of cupular deposits in the general population. They found small deposits in 125, medium sized deposits in 20; and large deposits in four; in none did the deposits exceed the size of those found in the three patients with benign paroxysmal positional nystagmus. Schuknecht proposed the following mechanism to explain benign paroxysmal positional nystagmus. Otoconia from a degenerating utricular macule settle on the cupula of the posterior canal, causing it to become heavker than the surrounding endolymph. When the patient moves from the sitting to the head-hanging postion (standard positioning maneuver), the posterior canal moves from an inferior to a superior position and utriculofugal displacement of the cupula occurs. The long latency before nystagmus onset reflects the period of time required for the otoconial mass to be displaced, and fatigability is caused by disbursement of particles in the endolymph. It is difficult for one to compare reports of so-called "typical" benign paroxysmal positional nystagmus, since most of them do not include recordings of the nystagmus. Whether the direction of benign paroxysmal positional nystagmus is always the same and whether paroxysmal positional nystagmus of central origin differs in direction from that of peripheral origin is not established. Benign paroxysmal positional nystagmus is usually described as being rotatory with the upper pole of the eye beating toward the undermost ear. 2 The consistency of this pattern and the amplitude of the actual horizontal and vertical components in each eye, to our knowledge, have not been reported. If, as Schuknecht suggests, benign paroxysmal positional nystagmus originates from the posterior canal of the undermost ear, it should have similar horizontal and vertical components in each patient, i.e., those predicted by the known anatomical connections between the posterior canal and the extraocular muscles. Furthermore, the profile of the slow component velocity obtained from recordings .of benign paroxysmal positional nystagmus should be helpful in understanding the dynmnics of the abnormal cupula of the posterior canal. With these practical and theoretical considerations in mind we studied electro-
oculographic recordings of benign paroxysmal positional nystagmus from 32 patients. CASE MATERIAL AND METHODS
Electro-oculographic recordings of benign paroxysmal positional nystagmus were made in 32 patients. Unilateral vertical (left eye) and bitemporal horizontal eye movements were recorded in 24 patients, and bilateral monocular horizontal and vertical eye movements were recorded in the other eight. Details of the recording system are reported elsewhere. 9 The nystagmus was induced by a rapid change from the sitting to the head-hanging-right and headhanging-left positions (as described by Dix and Hallpike2). The patient's eyes were opened behind Frenzel glasses in a darkened room. The duration of the standard position change was approximately 2 seconds. The effects of slower and more rapid positional changes were also studied. Each patient reported a typical history of brief episodes of vertigo induced by position change, and each demonstrated paroxysmal positional nystagmus that fatigued on repeated positioning. The clinical diagnoses were as follows: post-traumatic, 9; vestibulopathy of unknown cause (benign paroxysmal positional nystagmus and vestibular paresis ~ on caloric testing), 10; vertebral basilar insufficiency, 2; multiple sclerosis, 1; idiopathic (isolated), 10. The average age was 56.4---13.9 years with a range of 34 to 75 years. Post-traumatic benign paroxysmal positional nystagmus occurred in younger patients (mean age, 45--+15 years), whereas idiopathic benign paroxysmal positional nystagmus was more common in older patients (mean age, 63-+7 years). There were 19 females and 13 males. In 23 patients benign paroxysmal positional nystagmus occurred in only one head-hanging position, whereas in nine it occurred in both. In the latter patients the nystagrnus was more prominent in one position and its direction was the same in both positions. Fourteen patients had significant (p
