A Dictionary of Neurological Signs

Pupillary Reflexes

P

Cross References

Blepharospasm; Diplopia; Divisional palsy; Ewart phenomenon; Horner’s syndrome; Jaw winking; Miosis; Mydriasis; Pseudoptosis; Pupil sparing; Synkinesia, Synkinesis

Ptyalism

- see SIALORRHEA

Pulfrich Phenomenon

The Pulfrich phenomenon is the observation that a pendulum swung from side to side appears to traverse a curved trajectory. This is a stereo-illusion resulting from latency disparities in the visual pathways, most commonly seen as a consequence of conduction slowing in a demyelinated optic nerve following unilateral optic neuritis.

References

Diaper CJ. Pulfrich revisited. Survey of Ophthalmology 1997; 41: 493-499 Rushton D. Use of the Pulfrich pendulum for detecting abnormal delay in the visual pathways in multiple sclerosis. Brain 1975; 98: 283-296

Cross References

Phosphene; Relative afferent pupillary defect (RAPD)

“Pull Test”

- see POSTURAL REFLEXES

Pupillary Reflexes

Two pupillary reflexes are routinely examined in clinical practice:

●Light reflex:

The eye is illuminated directly and the reaction (constriction) observed; the consensual light reflex is observed by illuminating the contralateral eye. In an eye with poor acuity, a relative afferent pupillary defect may be observed using the “swinging flashlight test.” The afferent pathway subserving the light reflex is optic nerve to thalamus, brainstem, and Edinger-Westphal nucleus, with the efferent limb (pupillomotor parasympathetic fibers) in the oculomotor (III) nerve. The contralateral (consensual) response results from fibers crossing the midline in the optic chiasm and in the posterior commissure at the level of the rostral brainstem.

Paradoxical constriction of the pupil in darkness (Flynn phenomenon) has been described.

●Accommodation reflex:

This is most conveniently examined by asking the patient to look into the distance, then focus on a near object (sufficiently close to necessitate convergence of the visual axes) when pupil constriction should occur (accommodation-con- vergence synkinesis). The afferent pathways subserving this response are less certain than for the light reflex, and may involve the occipital cortex, although the final (efferent)

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P	Pupil Sparing

pathway via Edinger-Westphal nucleus and oculomotor nerve is common to both accommodation and light reflexes.

In comatose patients, fixed dilated pupils may be observed with central diencephalic herniation, whereas midbrain lesions produce fixed midposition pupils.

A dissociation between the light and accommodation reactions (light-near pupillary dissociation, q.v.) may be observed.

References

Kawasaki A. Approach to the patient with abnormal pupils. In: Biller J (ed.). Practical neurology (2nd edition). Philadelphia: Lippincott Williams & Wilkins, 2002: 135-146

Cross References

Argyll Robertson pupil; Ciliospinal response; Cortical blindness; Flynn phenomenon; Light-near pupillary dissociation; Miosis; Mydriasis; Relative afferent pupillary defect (RAPD); Swinging flashlight sign

Pupil Sparing

Oculomotor (III) nerve lesions may be pupil sparing (normal response to light) or pupil-involving (mydriasis, loss of light reflex). The latter situation usually implies a “surgical” cause of oculomotor palsy (e.g., posterior communicating artery aneurysm), especially if extraocular muscle function is relatively preserved. Pupil sparing suggests a “medical” cause (e.g., diabetes mellitus, hypertension) especially if the palsy is otherwise complete (complete ptosis, eye deviated downwards and outwards). This disparity arises because pupillomotor fibers run on the outside of the oculomotor nerve, and are relatively spared by ischemia but are vulnerable to external compression. However, the distinction is not absolute; imaging for an aneurysm (by means of spiral CT, MRA, or catheter angiography) may be necessary if the clinical scenario leaves room for doubt.

Cross References

Oculomotor (III) nerve palsy; Ophthalmoparesis, Ophthalmoplegia; Ptosis; Pupillary reflexes

Pure Word Blindness

- see ALEXIA

Pure Word Deafness

Pure word deafness is a rare condition characterized by an inability to comprehend and discriminate spoken language, despite adequate hearing as measured by audiometry, and with preserved spontaneous speech, reading, reading comprehension, and writing (i.e., no aphasia, alexia, agraphia). Lip reading may assist in the understanding of others who sometimes seem to the patient as though they are speaking in a foreign language. Patients can copy and write spontaneously, follow written commands, but cannot write to dictation. Word repetition tasks are impaired. There may be associated amusia, depending on the precise location of cerebral damage.

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Pyramidal Signs, Pyramidal Weakness

P

Pure word deafness has been variously conceptualized as a form of auditory agnosia or a subcortical sensory aphasia.

Pure word deafness is most commonly associated with bilateral lesions of the temporal cortex or subcortical lesions whose anatomical effect is to damage the primary auditory cortex or isolate it (e.g., from Wernicke’s area) through lesions of the auditory radiation; unilateral lesions producing this syndrome have been reported. Very rarely pure word deafness has been associated with bilateral brainstem lesions at the level of the inferior colliculi.

References

Meyer B, Kral T, Zentner J. Pure word deafness after resection of a tectal plate glioma with preservation of wave V of brain stem auditory evoked potentials. Journal of Neurology, Neurosurgery and Psychiatry

1996; 61: 423-424

Roberts M, Sandercock P, Ghadiali E. Pure word deafness and unilateral right temporo-parietal lesions: a case report. Journal of Neurology, Neurosurgery and Psychiatry 1987; 50: 1708-1709

Tanaka Y, Yamadori A, Mori E. Pure word deafness following bilateral lesions. A psychophysical analysis. Brain 1987; 110: 381-403

Cross References

Agnosia; Amusia; Aphasia

Pyramidal Signs, Pyramidal Weakness

- see HEMIPARESIS; UPPER MOTOR NEURONE (UMN) SYNDROME; WEAKNESS

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Q

Quadrantanopia

Quadrantanopia (quadrantanopsia), a defect in one quarter of the visual field, suggests an optic radiation lesion. Occipital lobe pathology is the most common cause of both inferior and superior quadrantanopias, although temporal lobe pathology damaging Meyer’s loop typically must be considered with a superior homonymous quadrantanopia (“pie-in-the-sky” defect). Parietal lobe lesions may produce inferior quadrantic defects, usually accompanied by other localizing signs. Damage to extrastriate visual cortex (areas V2 and V3) has also been suggested to cause quadrantanopia; concurrent central achromatopsia favors this localization.

References

Horton JC, Hoyt WF. Quadrantic visual field defects. A hallmark of lesions in extrastriate (V2/V3) cortex. Brain 1991; 114: 1703-1718 Jacobson DM. The localizing value of quadrantanopia. Archives of Neurology 1997; 54: 401-404

Cross References

Achromatopsia; Hemianopia; “Pie-in-the-sky” defect

Quadriparesis, Quadriplegia

Quadriparesis and quadriplegia (tetraparesis, tetraplegia) refer to weakness (partial or total, respectively) of all four limbs which may be of upper motor neurone or, less commonly, lower motor neurone type (e.g., in Guillain-Barré syndrome). As with hemiplegia, upper motor neurone quadriplegia may result from lesions of the corticospinal pathways anywhere from motor cortex to cervical cord via the brainstem, but is most commonly seen with brainstem and upper cervical cord lesions. In such circumstances, respiration may be affected.

Cross References

Hemiparesis; Paraplegia

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R

Rabbit Syndrome

Rabbit syndrome is a rest tremor of the perioral and nasal muscles, which may occur with antipsychotic drug therapy and in idiopathic Parkinson’s disease. It is therefore presumably related to dopamine deficiency. Drug-induced rabbit syndrome may remit with drug withdrawal.

References

Decina P, Caracci G, Scapicchio PL. The rabbit syndrome. Movement Disorders 1990; 5: 263

Cross References

Parkinsonism

“Raccoon Eyes”

“Raccoon eyes” refers to an appearance of bilateral periorbital ecchymosis, appearing 48-72 hours after an anterior basal skull fracture.

Radiculopathy

A radiculopathy is a disorder of nerve roots, causing pain in a radicular distribution, paresthesia, sensory diminution or loss in the corresponding dermatome, and lower motor neurone type weakness with reflex diminution or loss in the corresponding myotome. Radiculopathies may be single or multiple (polyradiculopathy, e.g., cauda equina syndrome). There may be concurrent myelopathy, typically of extrinsic or extramedullary type.

Most radiculopathies are in the lumbosacral region (60-90%), followed by the cervical region (5-30%).

Electrophysiological studies may be helpful in distinguishing radiculopathy from a neuropathy or plexopathy: sensory nerve action potentials (SNAPs) are normal for intrathecal root lesions, and EMG shows involvement of paraspinal muscles.

●Recognized causes of radiculopathy include: Structural lesions:

Compression: disc protrusion: cervical (especially C6, C7), lumbar (L5, S1) >>> thoracic; bony metastases; spondylolisthesis; fracture; infection.

Root avulsion, e.g., C5/C6, “waiter’s tip” posture; C8/T1, claw hand +/− Horner’s syndrome.

Diabetic polyradiculopathy: thoraco-abdominal, lumbosacral (= diabetic amyotrophy, also known as diabetic lumbar sacral plexopathy, proximal diabetic neuropathy; especially involves L2-L4).

Neoplasia: with meningeal symptoms, due to spread from carcinoma of breast or lung, melanoma, nonHodgkin’s lymphoma, leukemia.

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R	Rebound Phenomenon

Infection: HIV (CMV late in the course), Borrelia (Lyme disease), syphilis (tabes dorsalis), herpes zoster (thoracic > cervical > lumbosacral; sensory >> motor), leprosy.

Demyelination: Guillain-Barré syndrome, chronic inflammatory demyelinating polyradiculopathy (CIDP).

References

Chad DF. Nerve root and plexus disorders. In: Bogousslavsky J, Fisher M (Eds.). Textbook of neurology. Boston: ButterworthHeinemann, 1998: 491-506

Feldman EL, Grisold W, Russell JW, Zifko U. Atlas of neuromuscular disease. A practical guideline. Vienna: Springer, 2005: 117-139

Cross References

Cauda equina syndrome; Lasègue’s sign; Myelopathy; Neuropathy; Paresthesia; Plexopathy; Reflexes; “Waiter’s tip” posture; Weakness

Rebound Phenomenon

This is one feature of the impaired checking response seen in cerebellar disease, along with dysdiadochokinesia and macrographia. It may be demonstrated by observing an overshoot of the outstretched arms when they are released suddenly after being pressed down by the examiner, or suddenly releasing the forearm flexed against resistance so that it hits the chest (Stewart-Holmes sign). Although previously attributed to hypotonia, it is more likely a reflection of asynergia between agonist and antagonist muscles.

Cross References

Asynergia; Ataxia; Dysdiadochokinesia; Dysmetria; Hypotonia, Hypotonus; Macrographia

Recruitment

Recruitment, or loudness recruitment, is the phenomenon of abnormally rapid growth of loudness with increase in sound intensity, which is encountered in patients with sensorineural (especially cochlear sensory) hearing loss. Thus patients have difficulty with sounds of low to moderate intensity (“Speak up, doctor”) but intense sounds are uncomfortably loud (“There’s no need to shout, doctor!”). Speech discrimination is relatively unimpaired in conductive hearing loss.

“Recruitment” may also be used to refer to pathological “spread” of tendon reflexes, implying broadening of their receptive field.

Cross References

Reflexes

Reduplicative Paramnesia

Reduplicative paramnesia is a delusion in which patients believe familiar places, objects, individuals or events to be duplicated. The syndrome is probably heterogeneous and bears some resemblance to the Capgras delusion as described by psychiatrists.

Reduplicative paramnesia is commoner with right (nondominant) hemisphere damage; frontal, temporal and limbic system damage has

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Reflexes

R

been implicated. This may occur transiently as a consequence of cerebrovascular disease, following head trauma, or even after migraine attacks, or more persistently in the context of neurodegenerative disorders, such as Alzheimer’s disease.

References

Benson DF, Gardner H, Meadows JC. Reduplicative paramnesia. Neurology 1976; 26: 147-151

Cross References

Delusion; Paramnesia

Reflexes

Reflex action – a sensory stimulus provoking an involuntary motor response – is a useful way of assessing the integrity of neurological function, since disease in the afferent (sensory) limb, synapse, or efferent (motor) limb of the reflex arc may lead to dysfunction, as may changes in inputs from higher centres.

Different types of reflex may be distinguished. Muscle tendon reflexes (myotactic reflexes) may be either tonic (in response to a static applied force: “stretch reflex”) or phasic (in response to a brief applied force, for example a blow from a tendon hammer to the muscle tendon). The latter are of particular use in clinical work because of their localizing value (see Table). However, there are none between T2 and T12, and thus for localization one is dependent on sensory findings, or occasionally cutaneous (skin or superficial) reflexes, such as the abdominal reflexes.

Reflex	Root Value
Jaw jerk	Trigeminal (V) nerve
Supinator (Brachioradialis, Radial)	C5, C6
Biceps	C5, C6
Triceps	C7
Finger flexion (Digital)	C8, T1
Abdominal	T7 to T12
Cremasteric	L1, L2
Knee (Patellar)	L3, L4
Hamstring	L5, S1
Ankle (Achilles)	(L5) S1 (S2)
Bulbocavernosus	S2, S3, S4
Anal	S4, S5

Tendon reflex responses are usually graded on a five point scale:

−absent (areflexia; as in lower motor neurone syndromes, such as

peripheral nerve or anterior horn cell disorders; or acute upper motor neurone syndromes, e.g., “spinal shock”)

+/− present only with reinforcement (Jendrassik’s maneuver); hyporeflexia

+normal

++brisk normal

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R	Relative Afferent Pupillary Defect (RAPD)

+++pathologically brisk (hyperreflexia, as in upper motor neurone syndromes)

Reflex “spread,” or “recruitment,” for example a finger jerk when eliciting the supinator or biceps jerk, is suggestive of corticospinal pathway (upper motor neurone) pathology, producing an enlarged receptive field for the reflex response; concurrent disruption of the local reflex arc may result in inverted reflexes (q.v.).

Reflex responses may vary according to the degree of patient relaxation or anxiety (pre-contraction). Moreover, there is interobserver variation in the assessment of tendon reflexes (as with all clinical signs): a biasing effect of prior knowledge upon reflex assessment has been recorded.

There is also a class or “primitive,” “developmental,” or “psychomotor” signs, present in neonates but disappearing with maturity but which may re-emerge with ageing or cerebral (especially frontal lobe) disease, hence sometimes known as “frontal release signs.”

References

Dick JPR. The deep tendon and the abdominal reflexes. Journal of Neurology, Neurosurgery and Psychiatry 2003; 74: 150-153

Donaghy M, Compston A, Rossor M, Warlow C. Clinical diagnosis. In: Donaghy M (ed.). Brain’s diseases of the nervous system (11th edition). Oxford: OUP, 2001: 1-59 [at 26-32]

Stam J, van Crevel H. Reliability of the clinical and electromyographic examination of tendon reflexes. Journal of Neurology 1990; 237: 427-431

Cross References

Age-related signs; Areflexia; Crossed adductor reflex; Facilitation; Frontal release signs; Hyperreflexia; Hyporeflexia; Inverted reflexes; Jendrassik’s maneuver; Lower motor neurone (LMN) syndrome; Primitive reflexes; Pupillary reflexes; Upper motor neurone (UMN) syndrome; Woltman’s sign. See also specific (named) reflexes

Relative Afferent Pupillary Defect (RAPD)

An afferent pupillary defect (APD), or relative afferent pupillary defect (RAPD), is an abnormal pupillary response in which the normally equal direct and consensual pupillary reflexes are asymmetric, the direct response being less than the consensual. This may be particularly evident using the “swinging flashlight” test, in which the two pupils are alternately illuminated every 2-3 seconds in a darkened room. Quickly moving the light to the diseased side may produce pupillary dilatation (Marcus Gunn pupil). Subjectively patients may note that the light stimulus seems less bright in the affected eye.

RAPD suggests an asymmetric optic nerve pathology, such as optic neuritis or tumor, causing a conduction defect; indeed this is the most sensitive sign of optic nerve pathology. Although visual acuity may also be impaired in the affected eye, and the disc appear abnormal on funduscopy, this is not necessarily the case. Since RAPD depends on asymmetry of optic nerve conduction, no defect may be observed if both optic nerves are affected.

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Retinitis Pigmentosa

R

RAPD has also been described with lesions of the retina, optic chiasm, optic tract (contralateral), brachium of the superior colliculus and pretectal nucleus (in the latter two situations without visual impairment).

References

Chen CJ, Scheufele M, Sheth M, Torabi A, Hogan N, Frohman EM. Isolated relative afferent pupillary defect secondary to contralateral midbrain compression. Archives of Neurology 2004; 61: 1451-1453 Kawasaki A. Approach to the patient with abnormal pupils. In: Biller J (ed.). Practical neurology (2nd edition). Philadelphia: Lippincott Williams & Wilkins, 2002: 135-146

Cross References

Amblyopia; Marcus gunn pupil, Marcus gunn sign; Pupillary reflexes; Swinging flashlight sign

Religiosity

- see HYPERRELIGIOSITY

Remote Atrophy

- see ATROPHY; “FALSE-LOCALIZING SIGNS”

Retinal Venous Pulsation

Venous pulsation is evident in the normal retina when observed with an ophthalmoscope, particularly at the margin of the disc. It is sometimes difficult to see, and may be more obvious in the recumbent position (because of higher pressure within the retinal veins). Venous pulsation is lost when intracranial pressure rises above venous pressure. This is a sensitive marker of raised intracranial pressure, and may be an early sign of impending papilledema; however, venous pulsation may also be absent in pseudopapilledema, and sometimes in normal individuals.

References

Jacks AS, Miller NR. Spontaneous retinal venous pulsation: etiology and significance. Journal of Neurology, Neurosurgery and Psychiatry

2003; 74: 7-9

Cross References

Papilledema; Pseudopapilledema

Retinitis Pigmentosa

Retinitis pigmentosa is a generic name for an inherited retinal degeneration, characterized clinically by typical appearances on ophthalmoscopy, with peripheral pigmentation of “bone-spicule” type, arteriolar attenuation, and eventually unmasking of choroidal vessels and optic atrophy. This process may be asymptomatic in its early stages, but may later be a cause of nyctalopia (night blindness), and produce a mid-peripheral ring scotoma on visual field testing.

A variety of genetic causes of isolated retinitis pigmentosa have been partially characterized:

●autosomal recessive: linked to chromosome 1q

●X-linked: Xp11, Xp21

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R	Retinopathy

●autosomal dominant: 3q, 6p, 8

In most cases, patients with retinitis pigmentosa have no associated systemic or extraocular abnormalities, but there are a number of multisystem disorders in which it occurs:

●Abetalipoproteinemia (Bassen-Kornzweig syndrome)

●Kearns-Sayre syndrome, mitochondrial disorders in general

●Lawrence-Moon-Bardet-Biedl syndrome

●Refsum’s disease

●Usher’s syndrome.

Cross References

Nyctalopia; Optic atrophy; Scotoma

Retinopathy

Retinopathy is a pathological process affecting the retina, with changes observable on ophthalmoscopy; dilatation of the pupil aids observation of the peripheral retina. Common causes include:

●Diabetes mellitus: various abnormalities may occur, in both insulindependent (IDDM) and noninsulin dependent (NIDDM) patients. “Background” diabetic retinopathy is manifest as microaneuryms, dot and blot hemorrhages, hard exudates, and diffuse retinal edema, all of which may be asymptomatic. Edema and hard exudates at the macula are a common cause of visual impairment. Proliferative retinopathy is characterized by neovascularization of the disc due to retinal hypoxia, typically in IDDM, with the risk of vitreous hemorrhage, traction retinal detachment and irreversible visual loss. Laser treatment of new vessels is the treatment of choice.

●Hypertension: hypertensive retinopathy may cause arteriolar constriction, with the development of cotton-wool spots; and abnormal vascular permeability causing flame-shaped hemorrhages, retinal edema and hard exudates; around the fovea, the latter may produce a macular star. Optic disc swelling may be seen in malignant hypertension. Arteriosclerosis, thickening of vessel walls with prolonged hypertension, may cause changes at arteriovenous crossings (“AV nipping”). Systemic hypertension is associated with an increased risk of branch retinal vein and central retinal artery occlusion.

●Drug-induced, for example, antimalarials (chloroquine); chlorpromazine.

●Retinitis pigmentosa (q.v.).

●Serous retinopathy or chorioretinopathy: leakage of fluid into the subretinal space, causing unilateral sudden nonprogressive visual loss.

●Cancer-associated retinopathy: arteriolar narrowing, optic atrophy.

●“Salt and pepper” retinopathy of Kearns-Sayre syndrome (mitochondrial disorder)

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