Monday, September 28, 2009

Neuroopthalmology of chiasm: Pearls

1. a prefixed chiasm can result in deficit resembling congruous visual field loss
2. A postfixed chiasm can resemble bilateral optic neuropathy
3. Fixation blindness: attempts to focus on a near target results in overlap of 2 nonseeing temporal fields, and everything beyond fixation appears to disappear.
4. See saw nystagmus seen with masses or trauma cause one eye and other alternately elevating, intorting, and then depressing and extorting, in a pendular fashion
5. Gliomas of chiasm are similar to optic nerves, presenting with decreased vision, optic atrophy and strabismus
6. In pituitary apoplexy, pain is frequently retroorbital, and field defect is classically bitemporal superior quadrantanopsias, due to upward expansion of the tumor, 70 % vomit, LP is abnormal, MRI is diagnostic test of choice, and substantial medicolegal risk resides therein. Men have nmore than women
7. Aneurysms causing chiasmal compression include supraclinoid ICA, the ICA-opthalm a junction, and occassionally cavernous or ACOM arteries. Nonruptured aneurysms causing compression require treatment usually with clipping rather than coiling (Continuum 2009).

Compressive optic neuropathies- dDx

taken from Continuum, Walsh and Hoyt, and Frohman

primary tumors
capillary/cavernous hemangioma

secondary tumors
metastatic carcinoma
nasopharyngeal carcinoma

APL syndrome
paraneoplastic syndrome
Wegener's granulomatosis
perioptic neuritis
Infectious (TB, syphilis, lyme)
Viral (HSV, HIV, CMV, EBV, Cox A, Hep A, Hep B, MMR, rubeola)
fungi (aspergillus, mucor, crypto, candida, histoplasmosis
parasites ( toxo, cysticercosis, toxicariasis)

Sarcoid and lupus related eye diseases


-- Anterior uveitis (most common)
--optic neuritis like
--retrobulbar optic neuropathy
-- granulomatous infiltration of the posterior orbital, intracanalicular, and intracranial optic nn.

All have disc edema (eventually)
May have slowly progressive or acute vision loss
diagnosis may be helped by findings of conjunctival nodules, uveitis, lacrimal gland enlargement, and vitreous opacities.

--PION more common, but AION occurs
-- can see IIH like presentation (except not really "idiopathic"

Thursday, September 24, 2009

Intranasal contact point headache

Rozen TD. In...: missing the point on brain MRI. Neuroimages. Neurology 2009; 1107.

Nasal septal deviation with contact point on the lateral naasal wall can trigger episodic or daily headaches. Its easy to visualize on MRI but rarely reported. Authors show an image of an MRI of 2 cases.

REM Behavior Disorder (RBD) Random Pearls

1. Differential diagnosis might include nocturnal seizures, which would occur earlier in night during NREM sleep; may or may not be able to diagnose without video/EEG
2. Differential diagnosis would include OSA which causes disruptions in sleep architecture and increased nighttime arousals so sleep study for that problem would be useful (pseudoRBD)
3. Drugs that cause/exacerbate include SSRI's, TCA's, MAO A inh, ETOH withdrawal,
4. Actions can be purposeful violence as patients are actually enacting dreams which are violent
5. Dreams of being chased are common (50 v. 8 % in RBD v. non RBD PD patients)
6. Associated with synucleinopathies ie. PD, CBD, LBD (52 % risk at 12 years)
7. Environmental precautions are medicolegally important including separate beds, locking windows, etc.
8. Effectively treated in 90 % with clonazepam, with most of the rest treated with carbamazepine.
9. Patients can have nonviolent behaviors as well as violent ones including included masturbating-like behavior and coitus-like pelvic thrusting, mimicking eating and drinking, urinating and defecating, displaying pleasant behaviors (laughing, singing, dancing, whistling, smoking a fictive cigarette, clapping and gesturing "thumbs up"), greeting, flying, building a stair, dealing textiles, inspecting the army, searching a treasure, and giving lessons. Speeches were mumbled or contained logical sentences with normal prosody. In PD with RBD (n = 60), 18% of patients displayed nonviolent behaviors. In this series (but not in incidental cases), all RBD patients with nonviolent behaviors also showed violent behaviors. NEUROLOGY 2009;72:551-557

Wednesday, September 23, 2009

Orthostatic tremor; writing tremor

Pearls Orthostatic tremor
--low amplitude high frequency tremor of legs
-- can'tstand but can walk
-- can auscultate legs
-- have to suspect in history
-- Original described by Ken Heilman in Arch Neurol
Writing tremor "hand shakes only when I write"
-- no tremor otherwise; task specific movement disorder
-- akin to dystonia
-- other tasks could be brushing teeth or shaving


Obvious-- age onset, duration, family history and response to ETOH
Subtle-- Body part affected                handwriting            associated signs     natural history
PD            hand, foot, chin lips            micrographic           +                        progressive
ET             hand, head, voice               tremor not micro      absent                insidious
1.  best position for postural tremor is fingers touching wings (elbows) up
2.  saying "ahhhh" shows rhythmical oscillation which is typical

Coat hanger sign of orthostatic hypotension and other MSA pearls/ signs

1.  Patients complain of characteristic muscular pain across neck or shoulder of coat hangar, when standing. 
2.  Squeaky voice distinct from PD (needs oiling)
3.  Erectile dysfunction is present in nearly all men with MSA
4.  Check BP anyway can't rely on typical OH symptoms
5.  Inspiratory  stridor due to vocal cord paralysis or dystonia, may have OSA as well
6.  Cold dusky mottled hands
7.  Anterocollis think MSA, retrocollis think PSP
8.  Applause sign-- ask patients to clap quickly three times, if they continue that is frontal (PSP, PS not PD)
9.  Other frontal signs-- concrete proverbs highly characteristic of PSP, decreased verbal fluency
10. Palilalia / echolalia (seen in PSP) (equivalent of applause sign)
11. Absent vertical opthalmopledia, see slow vertical limited saccades occur first-- compare speed of horizontal and vertical saccades, and no fast phase nystagmus on OKN on vertical.  Beware, pursuit may be OK so must  test saccades.
12.  Unilateral apraxia (note COMPLAINS of apraxia)
13.  Unilateral jerky dystonia = CBD.  (Only other movement disorder that starts unilaterally is PD)

Tuesday, September 22, 2009

red flags for psychogenic movement disorders

credit AAN webcast Dr Sethi
wearing dark glasses indoors
triad of dark glasses, inappropriate underwear and teddy bears
failure to make or maintain eye contact
spells in front of audience
history given by significant other
extreme sensitivity to sounds, smells, bright lights, unusual precipitating factors

psychogenic dystonia

Helps if they have psychogenic tremor too.  See Fahn and Williams 1988 ADV NEUROL and Lang A Can J Neurol Sci 1995.
Features include abrupt onset, variability, bizarre extraneous movements, slow voluntary movements, resistance to passive movements, recurrence and remission, suggestibility, less distractibility.  Again, like parkinsonism, response to medication such as levodopa does not exclude psychogenic tremor.  It may be painful, exquisitely so.  Toes often are down and turned in, typical.  Big toe is usually down and in, if up it may be a striatal toe.

Psychogenic Parkinson's clues

Abrupt onset (71 % in Lang)
Maximal severity quickly
Spread of tremor with restraint of affected body part
Tremor is complex and distractible
Rigidity decreases with distraction (opposite of PD Froment's maneuver)

psychogenic movement disorders features

from Jankovic (5)
abrupt onset 79
distractability 72
variable amplitude and frequency 62
intermittent occurrence 35
inconsistent movements 30
variable direction 17
irregular pattern 12
suppressibility  12
incongruous movements  11
la belle indifference  11
suggestibility  sensory split 10
entrainment  9
active resistance to passive movement  8
deliberate slowing  7
nonpatterned  7
position induced  6