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Uhthoff’s Phenomenon
Uhthoff’s phenomenon (symptom) is the worsening of visual acuity
(“amblyopia” in Uhthoff’s 1890 description) with exercise in optic neuritis, reflecting the temperature sensitivity of demyelinated axons (i.e.,
reduced safety factor for faithful transmission of action potentials).
The term has subsequently been applied to exercise and/or temperature related symptoms in other demyelinated pathways. It has also
been described in the context of other optic nerve diseases, including
Leber’s hereditary optic neuropathy, sarcoidosis and tumor.
Evidence suggesting that Uhthoff’s phenomenon is associated
with an increased incidence of recurrent optic neuritis, and may be a
prognostic indicator for the development of multiple sclerosis, has
been presented.
Inverse Uhthoff sign, improved vision with warming, has been
described.
References
Guthrie TC, Nelson DA. Influence of temperature changes on multiple sclerosis: critical review of mechanisms and research potential.
Journal of the Neurological Sciences 1995; 129: 1-8
Scholl GB, Song HS, Wray SH. Uhthoff’s symptom in optic neuritis:
relationship to magnetic resonance imaging and development of multiple sclerosis. Annals of Neurology 1991; 30: 180-184
Selhorst JB, Saul RF. Uhthoff and his symptom. Journal of NeuroOphthalmology 1995; 15: 63-69 (erratum: Journal of NeuroOphthalmology 1995; 15: 264)
Uhthoff W. Untersuchungen uber die bei der multiplen Herdsklerose
vorkommenden Augenstorungen. Arch Psychitr Nervenkrankh 1890;
21: 55-106, 303-410
Cross References
Lhermitte’s sign; Phosphene
Unterburger’s Sign
Unterburger’s test examines the integrity of vestibulospinal connections
and attempts to define the side of a vestibular lesion. The patient is asked
to march on the spot with the eyes closed (i.e., proprioceptive and visual
cues are removed); the patient will rotate to the side of a unilateral
vestibular lesion (Unterburger’s sign). The test is not very useful, particularly in chronic, progressive, or partially compensated vestibular lesions.
Cross References
Proprioception; Vertigo
Upbeat Nystagmus
- see NYSTAGMUS
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Upper Motor Neurone (UMN) Syndrome
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Upper Motor Neurone (UMN) Syndrome
An upper motor neurone (UMN) syndrome constitutes a constellation
of motor signs resulting from damage to upper motor neurone pathways, i.e., proximal to the anterior horn cell. These may be termed
“pyramidal signs,” but since there are several descending motor pathways (e.g., corticospinal, reticulospinal, vestibulospinal), of which the
pyramidal or corticospinal pathway is just one, “upper motor neurone
syndrome” is preferable. “Long tract signs” may be a more accurate
term, often used interchangeably with “pyramidal signs.” The syndrome may be variable in its clinical features but common elements,
following the standard order of neurological examination of the motor
system, include:
●
Appearance:
usually normal, but there may be wasting in chronic UMN
syndromes, but this is usually not as evident as in lower
motor neurone syndromes; contractures may be evident in
chronically spastic limbs
●
Tone:
hypertonus, with spasticity, clasp-knife phenomenon and
sustained clonus
●
Power:
weakness, often in a so-called pyramidal distribution (i.e.,
affecting extensors more than flexors in the upper limb, and
flexors more than extensors in the lower limb); despite its
clinical utility, the term pyramidal is, however, a misnomer
(see Weakness)
●
Coordination:
depending on the degree of weakness, it may not be possible
to comment on the integrity of coordination in UMN syndromes; in a pure UMN syndrome coordination will be normal, but syndromes with both ataxia and UMN features do
occur (e.g., spinocerebellar syndromes, ataxic hemiparesis
syndromes)
●
Reflexes:
limb hyperreflexia, sometimes with additional reflexes
indicative of corticospinal tract involvement (Hoffmann’s
sign, Trömner’s sign, crossed adductor reflex); Babinski’s sign
(extensor plantar response); cutaneous reflexes (abdominal,
cremasteric) are lost.
The most reliable (“hardest”) signs of UMN syndrome are increased
tone, clonus, and upgoing plantar responses.
The clinical phenomena comprising the upper motor neurone syndrome may be classified as “positive” and “negative” depending on
whether they reflect increased or decreased activity in neural pathways:
●
Positive:
Exaggerated stretch/tendon reflexes, flexor spasms
Clonus
Autonomic hyperreflexia
Contractures
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Urgency
Negative:
Muscle weakness
Loss of dexterity
These features help to differentiate UMN from LMN syndromes,
although clinically the distinction is not always easy to make: a
“pyramidal” pattern of weakness may occur in LMN syndromes (e.g.,
Guillain-Barré syndrome) and acute UMN syndromes may cause flaccidity and areflexia (e.g., “spinal shock”).
References
Barnes MP, Johnson GR (eds.). Upper motor neurone syndrome and spasticity. Clinical management and neurophysiology. Cambridge: CUP, 2001
Cross References
Abdominal reflexes; Ataxic hemiparesis; Babinski’s sign (1); Claspknife phenomenon; Clonus; Contracture; Cremasteric reflex;
Hoffmann’s sign; Hyperreflexia; Hypertonia, Hypertonus; Lower
motor neurone (LMN) syndrome; Pseudobulbar palsy; Spasticity;
Trömner’s sign; Weakness
●
Urgency
- see INCONTINENCE
Urinary Retention
Although urinary retention is often urological in origin (e.g., prostatic
hypertrophy) or a side effect of drugs (e.g., anticholinergics), it may have
neurological causes. It may be a sign of acute spinal cord compression,
with or without other signs in the lower limbs, or of acute cauda equina
compression, for example with a central L1 disc herniation. Sometimes
the level of the pathology is several segments above that expected on the
basis of the (“false localizing”) neurological signs. Loss of awareness of
bladder fullness may lead to retention of urine with overflow.
A syndrome of urinary retention in young women has been
described, associated with myotonic-like activity on sphincter EMG;
this condition may be associated with polycystic ovary disease and is
best treated with clean intermittent self-catheterization.
References
Fowler CJ. Investigation of the neurogenic bladder. In: Hughes RAC
(ed.). Neurological Investigations. London: BMJ Publishing 1997: 397-414
Jamieson DRS, Teasdale E, Willison HJ. False localizing signs in the
spinal cord. BMJ 1996; 312: 243-244
Cross References
Cauda equina syndrome; “False localizing signs”; Incontinence;
Myelopathy; Paraplegia; Radiculopathy
Useless Hand of Oppenheim
The deafferented hand or arm is functionally useless, and manifests involuntary movements due to severe proprioceptive loss. This was first
described in multiple sclerosis by Oppenheim in 1911, and reflects plaques
in the dorsal root entry zone of the relevant spinal cord segment(s).
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Utilization Behavior
References
Coleman RJ, Russon L, Blanshard K, Currie S. Useless hand of
Oppenheim – magnetic resonance imaging findings. Postgraduate
Medical Journal 1993; 69: 149-150
Oppenheim H. Discussion on the different types of multiple sclerosis.
BMJ 1911; 2: 729-733
Cross References
Proprioception; Pseudoathetosis; Pseudochoreoathetosis
Utilization Behavior
Utilization behavior is a disturbed response to external stimuli, a component of the environmental dependency syndrome, in which seeing
an object implies that it should be used. Two forms of utilization
behavior are described:
●
Induced:
when an item is given to the patient or their attention is directed
to it, e.g., handing them a pair of spectacles which they put on,
followed by a second pair, which are put on over the first pair.
●
Incidental or Spontaneous:
when the patient uses an object in their environment without
their attention being specifically directed toward it.
Another element of the environmental dependency syndrome which
coexists with utilization behavior is imitation behavior (e.g., echolalia,
echopraxia). Primitive reflexes and hypermetamorphosis may also be
observed.
Utilization behavior is associated with lesions of the frontal lobe,
affecting the inferior medial area bilaterally. It has also been reported
following paramedian thalamic infarction.
References
De Renzi E, Cavalleri F, Facchini S. Imitation and utilization behavior.
Journal of Neurology, Neurosurgery and Psychiatry 1996; 61: 396-400
Lhermitte F, Pillon B, Serdaru M. Human autonomy and the frontal
lobes. Part I: imitation and utilization behavior: a neuropsychological
study of 75 patients. Annals of Neurology 1986; 19: 326-334
Schott JM, Rossor MN. The grasp and other primitive reflexes.
Journal of Neurology, Neurosurgery and Psychiatry 2003; 74: 558-560
Shallice T, Burgess PW, Schon F, Baxter DM. The origins of utilization behavior. Brain 1989;112: 1587-1598
Cross References
Automatic writing behavior; Echolalia; Echopraxia; Frontal lobe syndromes; Hypermetamorphosis; Imitation behavior; Primitive reflexes
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