Important CNS Signs

 Important CNS Signs

1.      Anisocoria

This refers to pupillary asymmetry, which may result from sympathetic or parasympathetic dysfunction. Sympathetic dysfunction results in Horner syndrome, in which the pupil is small but reacts to light. Hippus, a series of oscillating pupillary contractions seen in response to light, is a benign condition. Argyll-Robertson pupil, seen in neurosyphilis, is irregular and small; it does not react to light, but does accommodate.
In parasympathetic paralysis, the affected pupil is larger and reacts poorly or not at all to light. Injury to the ciliary ganglion or short ciliary nerves results in a tonic pupil, which is large and has slow or absent reaction to light. A benign form of tonic pupil is seen in Adie syndrome, Holmes-Adie syndrome (ie, tonic pupil with absent patellar and Achilles reflexes), and Ross syndrome (ie, tonic pupil with hyporeflexia and progressive segmental hypohidrosis).

2.      Anosognosia

This refers to denial of illness and typically is seen in patients with right frontoparietal lesions, resulting in left hemiplegia that the patient denies. A form of visual anosognosia (Anton syndrome) is seen in patients with bilateral occipital lobe infarctions; these patients with double hemianopsia (bilateral cortical blindness) deny that they are blind.

3.      Asterixis

This is seen in patients with metabolic encephalopathies. Momentary loss of tone and flapping of the hand are seen when the patient extends his arms in front with the wrists dorsiflexed.

4.      Ataxia

Heel-to-toe tandem gait is tested by asking the patient to walk with 1 foot directly in front of the other. Ataxia can be demonstrated in this manner.

5.      Beevor sign

This is seen with bilateral lower abdominal paralysis that results in upward deviation of the umbilicus when the patient tries to raise his head and sit up from the supine, recumbent position.

6.      Benediction hand

This is seen with lesions of the median nerve in the axilla and upper arm. When present, the index finger remains straight and the middle finger partially flexes when the patient tries to make a fist (assuming the position of the hand of a clergyman while saying the benediction).

7.      Bielschowsky sign

This refers to increasing separation of the images seen when a patient's head is tilted toward the side of a superior oblique (trochlear nerve) paralysis. This sign by itself is not diagnostic and should be used only as a supplement to other tests in suspected CN IV paralysis.

8.      Chvostek sign

This is seen in hypocalcemia. Tapping the cheek at the angle of the jaw precipitates tetanic facial contractions.

9.      Cogan sign

This is seen in myasthenia gravis. It refers to transient baring of the sclerae above the cornea as the patient resumes the primary eye position after looking down.

10.  Dalrymple sign

This refers to the upper-lid retraction seen in thyroid ophthalmopathy.

11.  Doll's-eye maneuver

This refers to turning the head passively with the patient awake and fixated or when the patient is in a coma. In the former, the eyes remain fixated at the original focus when all gaze pathways are normal; in the latter, the eyes deviate in the opposite direction when the brainstem is intact.

12.  Gower sign

This sign, seen in severe myopathies, occurs when the patient attempts to stand up from the floor. Patients first sit up, then assume a quadrupedic position, and then climb up their own legs by using their arms to push themselves up.

13.  Heterochromia iridis

This term refers to the difference in color of the 2 irides. It indicates early injury to the sympathetic system. Ipsilateral to the injury the iris is blue or green, while the contralateral iris is darker.

14.  Jaw jerk

This is elicited by placing the examiner's index finger on the patient's lower jaw and then striking it with the reflex hammer. An exaggerated reflex indicates the presence of a pontine lesion. When the rest of the examination findings are normal, it may indicate physiologic hyperreflexia.

15.  Kayser-Fleischer ring

This is a brownish ring around the limbus of the cornea. It is best demonstrated during an ophthalmologic slitlamp examination.

16.  Lhermitte sign

This refers to the sensation of electricity associated with cervical spinal cord lesions during passive or active flexion and extension of the neck. Once considered pathognomonic of multiple sclerosis, it simply is the result of electricity generation by the hypersensitive, demyelinated, or injured spinal cord; this sign can be associated with any lesion in or around the cord.

17.  Marcus-Gunn pupil

This sign requires a swinging-flashlight test to assess. As the flashlight swings from 1 eye to the other, the abnormal pupil dilates as the light swings back from the normal side. No anisocoria is seen. The phenomenon is also called a paradoxical pupillary reflex and indicates an afferent (optic nerve) pupillary defect.

18.  Milkmaid's grip

This refers to the inability to maintain a sustained grip commonly seen in patients with chorea.

19.  Moebius sign

This refers to weakness of ocular convergence (associated with proptosis) seen in dysthyroid ophthalmopathy.

20.  Myerson sign

Patients with Parkinson disease, particularly those with bilateral frontal lobe dysfunction, continue to blink with repeated glabellar taps.

21.  Nylen-Bárány sign

This is elicited by having the patient quickly lie down from the sitting position with the head turned to 1 side and hanging down 30^o below the horizontal over the edge of the examining table. The procedure is then repeated with the head turned to the other side.
The test is positive when the patient experiences vertiginous discomfort and exhibits nystagmus after a latency period of about 10 seconds. The nystagmus increases for about 10 seconds then fatigues in peripheral vestibular disease. In central lesions, nystagmus may occur with the head turned to either side, without discomfort to the patient, and without latency of onset or fatigue.

22.  Ondine curse

This refers to the failure of autonomic control of breathing when the patient falls asleep.

23.  Oommen sign

Have the patient close the eyes and place a pebble the size of an M&M candy on the palm of the examiner's left hand. Cross the patient's middle finger over the index finger on its dorsal aspect. With the examiner's right hand, hold the patient's crossed fingers and have the patient's 2 (crossed) fingertips touch the pebble at the same time. Ask the patient how many pebbles are in the examiner's hand. With normal stereognosis, the patient should answer that there are 2 pebbles. In cases of astereognosis, the patient reports feeling only 1 pebble.

24.  Opsoclonus

This refers to large-amplitude saccadic oscillations of the eyes in all directions, often exacerbated by refixation. They persist during sleep and are associated with brainstem and cerebellar lesions as well as a remote effect of certain carcinomas.

25.  Optokinetic nystagmus

This is elicited by using a rotating, striped drum or a moving, striped piece of cloth. As the patient's eyes fixate on a stripe, nystagmus seen in healthy individuals is due to the optokinetic reflex. Lesions in the anterior aspects of the visual pathways decrease the response, and lesions of the vestibular system result in a directional preponderance to the elicited nystagmus.

26.  Phalen sign

This refers to the aggravation of paresthesia and pain when the wrist is held in flexion (in patients with carpal tunnel syndrome).

27.  Roger sign

This is numbness of the chin in patients with lymphoreticular (and other types of) malignancies.

28.  Stellwag sign

This refers to decreased blinking frequency seen in thyroid ophthalmopathy.

29.  Summerskill sign

This refers to the bilateral upper- and lower-lid retraction associated with severe liver disease.

30.  Tinel sign

This refers to the tingling sensation elicited by tapping along the path of a regenerating nerve following injury. It helps to delineate the extent of nerve regeneration. The Tinel sign also can be observed in tardy ulnar palsy (palpation at the elbow) and carpal tunnel syndrome (tapping at the wrist).

31.  Trendelenburg sign

This refers to the pelvic tilt toward the side of the unaffected raised leg when walking in patients with lesions of the superior gluteal nerve.

32.  Trombone tongue

This is seen in patients with chorea. It refers to the unsteadiness of the tongue when the patient tries to protrude it outside the mouth.

33.  Tullio phenomenon

This refers to the induction of vertigo and nystagmus with acoustic stimuli in patients with labyrinthine disease.

34.  von Graefe sign

This refers to the lid lag on down gaze in patients with thyroid ophthalmopathy.