A Dictionary of Neurological Signs

Opisthotonos may be seen in: Coma; decerebrate rigidity Basilar meningitis Hydrocephalus

Structural lesions of the posterior fossa

Cerebellar fits due to intermittent tonsillar herniation

Acute drug- (neuroleptic-) induced dystonic reaction; or chronic feature of tardive dystonia

Tetanus

Syncope (especially in children)

Metabolic disorders: kernicterus, Gaucher’s disease (type II) Drug-induced: propofol

Pseudoseizures

As in decerebrate rigidity, opisthotonos may reflect unopposed extensor tone from the intact vestibular nuclei released from supratentorial control.

Cross References

Coma; Decerebrate rigidity; Emposthotonos

Oppenheim’s Sign

Oppenheim’s sign is a variant method for eliciting the plantar response, by application of heavy pressure to the anterior surface of the tibia, for example with the thumb, moving from patella to ankle. Extension of the hallux (upgoing plantar response, Babinski’s sign) is pathological. Like Chaddock’s sign, Oppenheim’s sign always postdates the development of Babinski’s sign as a reliable indicator of corticospinal pathway (upper motor neurone) pathology.

References

Pearce JMS. Oppenheim’s sign. In: Pearce JMS. Fragments of neurological history. London: Imperial College Press, 2003: 359-361

Van Gijn J. The Babinski sign: a centenary. Utrecht: Universiteit Utrecht, 1996

Cross References

Babinski’s sign (1); Chaddock’s sign; Gordon’s sign; Plantar response; Upper motor neurone (UMN) syndrome

Oppenheim’s Useless Hand Sign

- see USELESS HAND OF OPPENHEIM

Opsoclonus

Opsoclonus, or saccadomania, is an eye movement disorder characterized by involuntary bursts of polydirectional saccades (sometimes with a horizontal preference) without an intersaccadic interval (cf. squarewave jerks). Like ocular flutter, opsoclonus may be accurately characterized with oculography.

Although some normal individuals can voluntarily induce opsoclonus, generally it reflects mesencephalic or cerebellar disease affecting the omnipause cells which exert tonic inhibition of the burst neurones which generate saccades.

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Recognized causes of opsoclonus include:

●Paraneoplasia: in children with neuroblastoma (Kinsbourne’s syndrome); in adults the opsoclonus-myoclonus syndrome is most commonly associated with small-cell lung cancer but it may also occur in association with breast cancer in which case onco neural antibodies (anti-Ri, or type 2 antineuronal nuclear antibodies [ANNA-2]) may be detected in serum and CSF;

●Postinfectious: a monophasic disorder following respiratory or gastrointestinal infection;

●Intraparenchymal (especially mesencephalic) lesions, e.g., tumor, demyelination, sarcoidosis, metabolic/toxic encephalopathy.

Postinfectious opsoclonus generally remits spontaneously. Of the paraneoplastic disorders, opsoclonus associated with lung and breast tumors persists and the patients decline from their underlying illness; neuroblastoma associated opsoclonus may be steroid responsive.

Cross References

Ocular flutter; Saccadic intrusion, Saccadic pursuit; Square-wave jerks

Optic Aphasia

Optic aphasia is a visual modality-specific naming disorder. It has sometimes been grouped with associative visual agnosia, but these patients are not agnosic since they can demonstrate recognition of visually-presented stimuli by means other than naming, e.g., gesture. Moreover, these patients are not handicapped by their deficit in everyday life, whereas agnosic patients are often functionally blind. Objects that are semantically related can be appropriately sorted, indicating intact semantics. This is not simply anomia, since the deficit is specific to visual stimuli; objects presented in tactile modality, or by sound, or by spoken definition can be named. Naming errors are often semantic, and perseverations (“conduit d’approche”) are common. Perception is intact, evidenced by the ability to draw accurately objects which cannot be named. Reading is poorly performed.

Optic aphasia is associated with unilateral lesions of the left occipital cortex and subjacent white matter.

The neuropsychological explanation of optic aphasia is unclear. It may be a mild type of associative visual agnosia, despite the differences.

References

Beauvois MF. Optic aphasia: a process of interaction between vision and language. Philosophical Transactions of the Royal Society, Series B

1982; 298: 35-47

Farah MJ. Visual agnosia: disorders of object recognition and what they tell us about normal vision. Cambridge: MIT Press, 1995

Lhermitte F, Beauvois MF. A visual-speech disconnection syndrome: report of a case with optic aphasia, agnosic alexia and color agnosia. Brain 1973; 96: 695-714

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Cross References

Anomia; Conduit d’approche; Visual agnosia

Optic Ataxia

Optic ataxia is impaired voluntary reaching for a visually presented target, with misdirection and dysmetria. It may resemble cerebellar ataxia. Visual fixation is possible but reaching under visual guidance is impaired. Tactile search with the palm and fingers may be undertaken in searching for an object, using somatosensory cues to compensate for impaired access to visual information. Hence this may be characterized as a modality-specific apraxia, wherein visual information cannot be used to guide goal-directed movements. The disorder is both retinotopic and somatotopic.

Optic ataxia occurs with lesions of the intraparietal sulcus and regions medial and superior to it; the primary visual cortex is intact. It is one feature, along with psychic paralysis of gaze (“sticky fixation”) and simultanagnosia (visual disorientation), of Balint’s syndrome in which there is some evidence for parieto-occipital (and possibly frontal) lobe dysfunction (disconnection).

References

Perenin MT, Vighetto A. Optic ataxia: a specific disruption in visuomotor mechanisms. I. Different aspects of the deficit in reaching for objects. Brain 1988; 111: 643-674

Cross References

Apraxia; Ataxia; Balint’s syndrome; Dysmetria; Simultanagnosia; Visual disorientation; Visual form agnosia

Optic Atrophy

Optic atrophy is pallor of the optic nerve head as visualized by ophthalmoscopy. The temporal disc may appear pale in a normal fundus, so that optic atrophy can only be confidently diagnosed when there is also nasal pallor, although temporal pallor may follow damage to the macular fibre bundle with central visual defects.

Optic atrophy may be the consequence of any optic neuropathy which causes optic nerve damage leading to gliotic change of the optic nerve head. The appearance of optic atrophy is nonspecific with respect to etiology. Common causes include previous optic neuritis and chronic papilledema, but retinal lesions, optic chiasm and optic tract pathologies can all produce optic atrophy (e.g., inherited optic neuropathies, tobacco-alcohol amblyopia; vitamin B12 deficiency). “Hemianopic” optic atrophy, indicates involvement of the optic tract or lateral geniculate body.

Cross References

Disc swelling; Papilledema; Temporal pallor

Optokinetic Nystagmus (OKN), Optokinetic Response

Optokinetic nystagmus (OKN) is familiar to anyone who has watched a railway passenger observing passing telegraph poles from the window

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of a moving train: OKN is an involuntary rhythmic eye movement induced by observing moving stimuli. In clinical practice a striped drum serves to test both visual pursuit and saccades. Rotation of the stripe to the left produces leftward pursuit, followed by a compensatory saccade to the right, followed by pursuit to the left of the next stripe, with another compensatory saccade, and so on. Hence, OKN is a physiological nystagmus.

Parietal hemisphere lesions (vascular or neoplastic) typically impair OKN. Testing for OKN may be useful in patients with suspected hysterical visual loss, since OKN cannot occur unless visual function is present; the response is lost in blindness. An internuclear ophthalmoplegia may be made more evident by testing OKN.

Cross References

Cortical blindness; Internuclear ophthalmoplegia (INO); Nystagmus; Saccades; Vestibulo-ocular reflexes

Orofacial Dyspraxia

Orofacial dyspraxia, or buccofacial dyspraxia, is an inability to make voluntary, learned, movements with the orofacial musculature, such as blowing out a match, kissing, licking the lips.

Recognized causes of orofacial dyspraxia include:

●Transient accompaniment of Broca’s aphasia, conduction aphasia, and transcortical motor aphasia of cerebrovascular origin

●Trauma to pre-Rolandic area just above the Sylvian fissure

●In some patients with primary progressive aphasia; a related but distinct condition of “progressive loss of speech output with orofacial dyspraxia” has also been described.

Clinical and imaging studies show a strong correlation between orofacial dyspraxia and lesions in the frontal operculum; it may also occur with subcortical lesions involving periventricular and/or peristriatal white matter as well as the basal ganglia.

References

Tyrrell PJ, Kartsounis LD, Frackowiak RSJ, Findley LJ, Rossor MN. Progressive loss of speech output and orofacial dyspraxia associated with frontal lobe hypometabolism. Journal of Neurology, Neurosurgery and Psychiatry 1991; 54: 351-357

Cross References

Apraxia

Orthostatic Hypotension

Orthostatic hypotension or postural hypotension is the finding of a persistent drop in blood pressure on standing, defined as a greater than 20 mmHg fall in systolic pressure and/or a 5 mmHg fall in diastolic pressure one minute after a change from the supine to the upright position. Normally there is a drop in blood pressure of lesser magnitude on standing but this is usually quickly compensated for by the baroreceptor reflex. To demonstrate orthostatic hypotension, it may be necessary

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Oscillopsia O

to measure blood pressure not only on immediate standing but also after two to ten minutes, since the fall may be delayed. Measuring blood pressure automatically on a tilt table is also helpful in diagnosing orthostatic hypotension.

Symptoms which may be associated with orthostatic hypotension include exercise-induced or postprandial light-headedness, transient visual loss, blackouts (syncope), and pain in a “coathanger” distribution across the shoulders. There may be supine hypertension and reversal of the normal circadian blood pressure rhythm (normally lower at night), with increased frequency of micturition at night. Other features of autonomic dysfunction may be present, including dry eyes and dry mouth (xerophthalmia, xerostomia), a tendency to constipation, and lack of penile erections.

Orthostatic hypotension may be found in:

●Pure autonomic neuropathy

●Neurodegenerative disorders, such as multiple system atrophy, Parkinson’s disease, dementia with Lewy bodies

●Phaeochromocytoma

●Other causes of autonomic neuropathy (e.g., Guillain-Barré syndrome, amyloidosis).

However, the most common cause of orthostatic hypotension in hospital practice is probably dehydration or overzealous treatment with antihypertensive or diuretic agents.

Treatments for pure autonomic failure encompass both nonpharmacological approaches (e.g., increased salt intake, head-up bed tilt, wearing a G-suit) and pharmacological therapies, including fludrocortisone, ephedrine, and midodrine.

References

Mathias CJ, Kimber JR. Treatment of postural hypotension. Journal of Neurology, Neurosurgery and Psychiatry 1998; 65: 285-289

Cross References

Neuropathy; Parkinsonism; Xerophthalmia, Xerostomia

Oscillopsia

Oscillopsia is an illusory movement of the environment due to excessive slip of images on the retina (“retinal slip”) during active or passive head movement, producing a complaint of blurring, jumping, or oscillation of the visual representation of the environment. Oscillopsia is most often due to acquired bilateral loss of vestibular function (loss of the vestibuloocular reflexes). Other recognized causes of oscillopsia include:

●Acquired nystagmus

●Superior oblique myokymia

●Other ocular oscillations.

Oscillopsia does not occur in congenital nystagmus, nor in opsoclonus, presumably due to the operation of the visual suppression mechanism which normally operates during saccadic eye movements.

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Oscillopsia may be treated with clonazepam; if due to acquired pendular nystagmus anticholinesterase or alcohol may help.

References

Leigh RJ. Oscillopsia: impaired vision during motion in the absence of the vestibulo-ocular reflex. Journal of Neurology, Neurosurgery and Psychiatry 1998; 65: 808

Cross References

Myokymia; Nystagmus; Opsoclonus; Vestibulo-ocular reflexes

Overflow

- see DYSTONIA; SYNKINESIA, SYNKINESIS

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P

Pagophagia

- see PICA

Palatal Myoclonus

Palatal myoclonus, also known as palatal tremor, is a focal myoclonic syndrome characterized by rhythmic, unilateral or bilateral, palatal contractions which continue during sleep. This may be asymptomatic, or there may be a clicking sound in the inner ear (especially in essential palatal myoclonus). There may be associated contractions of external ocular muscles (oculopalatal myoclonus), larynx, neck, diaphragm (respiratory myoclonus, diaphragmatic flutter, or Leeuwenhoek’s disease), trunk, and limbs, which may bring the palatal myoclonus to attention. Palatal myoclonus may be accompanied by pendular nystagmus and oscillopsia.

Palatal myoclonus is associated with lesions interrupting pathways between the red nucleus, inferior olivary nucleus and dentate nucleus (Guillain-Mollaret triangle). Hypertrophy of the inferior olivary nucleus may be evident neuroradiologically (structural or functional imaging) and pathologically. This is a consequence of a lesion in the dentato-olivary pathway which leads to transsynaptic degeneration and hypermetabolism of the olivary nucleus. Although many cases are essential/idiopathic, recognized symptomatic causes of palatal myoclonus include vascular lesions, trauma, neoplasia, demyelination, epilepsy and, rarely, adult-onset Alexander’s disease.

Drug treatment of palatal myoclonus is often unsuccessful, although reports of benefit with 5-hydroxytryptophan, carbamazepine, sodium valproate, clonazepam, baclofen, and even sumatriptan have appeared. Botulinum toxin injections may also help.

Cross References

Eight-and-a-half syndrome; Myoclonus; Nystagmus; Oscillopsia; Tinnitus

Palatal Reflex

- see GAG REFLEX

Palilalia

Palilalia is a disorder of articulation characterized by the involuntary repetition of syllables within a word, whole words, or phrases, hence a reiterative speech disorder. The term stutter may be used for repetition of single syllables, and the term palilogia has sometimes been used for the repetition of phrases, to distinguish from palilalia. These phenomena may be encountered in:

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Parkinson’s disease (along with bradylalia, slowness of speech) Progressive supranuclear palsy

Gilles de la Tourette syndrome (along with vocal and motor tics) Pick’s disease, as part of the so-called PES syndrome (palilalia, echolalia, stereotypy) or the PEMA syndrome (palilalia, echo-

lalia, mutism, amimia)

Late stages of Alzheimer’s disease

Postencephalitic parkinsonism (von Economo’s disease) Fahr’s disease (bilateral basal ganglia calcification)

Normal finding in children below the age of about six years

In pathological states, palilalia may reflect difficulty in set shifting, as seen in frontal lobe (frontal convexity) syndromes.

Cross References

Bradylalia; Echolalia; Frontal lobe syndromes; Hypomimia; Mutism; Parkinsonism; Stereotypy; Stutter; Tic

Palilogia

- see PALILALIA

Palinacusis

Palinacusis, or palinacousis, is the persistence of prior auditory perception. Although sometimes classified as an illusory experience, musical hallucinations may occur concurrently. The symptom may be related to seizures of temporal lobe origin.

References

Takeshi T, Matsunaga K. Musical hallucinations and palinacousis.

Psychopathology 1999; 32: 57-59

Cross References

Hallucination; Illusion

Palinopsia

Palinopsia is an illusory visual phenomenon characterized by the persistence or recurrence of visual images immediately after the stimulus has been removed, hence visual perseveration. This is distinct from the physiological after-image. It may be associated with polyopia. The description of the symptom may lead to it being mistaken for diplopia (“pseudodiplopia”).

Palinopsia occurs most frequently in the context of a left homonymous hemianopia, secondary to right occipitotemporal or occipitoparietal lesions: these may be vascular, neoplastic, metabolic, ictal, or drugor toxin-induced (e.g., carbon monoxide poisoning). It has also been described with retinal and optic nerve disease, and occasionally in normal individuals.

References

Michel EN, Troost BT. Palinopsia: cerebral localization with computed tomography. Neurology 1980; 30: 887-889

Pomeranz HD, Lessell S. Palinopsia and polyopia in the absence of drugs or cerebral disease. Neurology 2000; 54: 855-859

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Papilledema P

Smith PEM, Shah P, Sharpe J, Todd A, Goringe AP. Palinopsia. Lancet 2003; 361: 1098

Stagno SJ, Gates TJ. Palinopsia: a review of the literature. Behavioral Neurology 1991; 4: 67-74

Cross References

Hemianopia; Illusion; Perseveration; Polyopia

Pallesthesia

Pallesthesia is the appreciation of vibration sensation; its loss pallanesthesia.

Cross References

Vibration

Palmomental Reflex

The palmomental reflex consists of contraction of the mentalis muscle induced by stroking the ipsilateral palm with a blunt object. It may indicate damage to the contralateral paracentral cortex or its connections, but since it is observed in about one quarter of normal adults and is very common in the normal elderly, and may occur in other conditions, both its sensitivity and specificity are low. It may be considered a frontal release sign or primitive reflex, but is less specific than the grasp reflex. Induction of the reflex by stimulation of areas other than the palm is more likely to be associated with cerebral damage.

References

Owen G, Mulley GP. The palmomental reflex: a useful clinical sign?

Journal of Neurology, Neurosurgery and Psychiatry 2002; 73: 113-115

Cross References

Age-related signs; Frontal release signs

Papilledema

Papilledema is swelling (edema) of the optic nerve head due to raised intracranial pressure (cf. other causes of disc swelling, which may cause pseudopapilledema).

A number of stages of papilledema are described: in the acute stage, the only findings may be edema at the superior and inferior poles of the disc, absence of spontaneous venous pulsation, and enlargement of the blind spot. As papilledema progresses the whole disc is involved and splinter hemorrhages may be evident at the disc margin. These early stages may be asymptomatic, or may be associated with transient losses of vision (obscurations), often provoked by activities or movements which further raise intracranial pressure, thus compromising retinal perfusion pressure. Enlargement of the blind spot and constriction of the visual field may be evident, but visual acuity is often unimpaired (cf. disc swelling due to papillitis). Chronic papilledema produces gliosis of the optic nerve head and eventually optic atrophy (“sequential optic atrophy”) with nerve fibre damage and permanent visual field defects.

Cross References

Blind spot; Disc swelling; Obscurations; Optic atrophy pseudopapilledema; Retinal venous pulsation; Scotoma

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Paraballismus

- see BALLISM, BALLISMUS; HEMIBALLISMUS

Paradoxical Breathing

The normal movement of the diaphragm (i.e., down in inspiration, causing outward abdominal wall movement) may be reversed (paradoxical) in conditions which cause diaphragm weakness (i.e., inward abdominal wall movement on inspiration), e.g., Guillain-Barré syndrome, acid-maltase deficiency, phrenic nerve injury, hence paradoxical abdominal movement, abdominal paradox, paradoxical breathing, or paradoxical diaphragm movement. This may be detectable clinically or by X-ray screening of the diaphragm. Vital capacity is lower when lying compared to standing. Paradoxical diaphragm movement is a potentially alarming sign since it may indicate incipient respiratory failure.

The term paradoxical breathing may also be used to describe thorax and abdomen moving in different directions when breathing, as with increased upper airway resistance.

Cross References

Myopathy

Paradoxical Flexor Reflex

- see GORDON’S SIGN

Paradoxical Head Tilt

- see BIELSCHOWSKY’S SIGN, BIELSCHOWSKY’S TEST

Paradoxical Triceps Reflex

- see INVERTED REFLEXES

Paragrammatism

- see WERNICKE’S APHASIA

Paragraphia

- see AGRAPHIA

Parakinesia, Parakinesis

These terms have been used in different ways by different authors, to describe:

●A volitional purposeful act designed to camouflage or draw attention away from an involuntary movement, such as chorea;

●Strange movements of presumed psychogenic origin. It should be remembered that many movements previously thought to conform to this definition have subsequently been recognized to have an organic basis (e.g., klazomania).

The terms are now seldom used.

Cross References

Chorea, Choreoathetosis; Dyskinesia; Klazomania

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