Wednesday, January 24, 2007

Mimics of GBS Part II

Chemical toxins
vacor (rodenticide)ingested due to homicidal or suicidal intent. Impairs fast axon transport. Clinical findings are initially abdominal pain, nausea, vomiting, necrosis of pancreas beta cells causes hyperglycemia, rapid distal motor/sensory/Autonomic neuropathy with weakness, areflexia, dysesthesias, OH, urine retention, and cranial neuropathy, then later stupor, EEG changes, DKA, EKG changes. Long term residua often include DM and ANS dysfunction. Acute tx is gastric lavage and induced emesis.

Organophosphates -- found in malathion, parathion, dursban. 10-20 days after exposure they produce a distal axonopathy, calf cramps, extremity paresthesias and distal weaknesss. A SEPARATE syndrome is NMJ disorder with cholinergic toxicity and respiratory insufficiency.

n-Hexane solvent associated with glue sniffing and industrial exposure. Clinical includes distal sensory loss and severe weakness that progresses for months after exposure ends.

CV-- amiodorone, streptokinase
Hem-- cytarabine, suramin.

amiodoarone chronic progressive predominantly distal s-m neuropathy. NCS show distal latency prolongation and slowing to 11 m/s. Dose is 200-400 mg per day.

streptokinase-- 10-20 cases, 10-20 days after exposure, paresthesias of hands and feet, cndxn blocks, elevated CSF protein, coincident to peak SKN titers, dramatic response to IVIG.

cytarabine-- 0.6 % of cases with doses more than 200 mg/m2/d. progressive distal sensorimotor neuropathy, hours to days after last treatment.

Suramin -- PN in 40 % of patients with levels> 350 ug/ml Rarely GBS like presentation.

Churg-Strauss s-- may resemble GBS. Eosinophilia is seen. Tx with pred/MTX. Asthma, vasculitic lung involvment, eosinophilia and mononeuropathy are common but not universal.

Other cryoglobulinemia, PAN.

AIP-- Motor PN.
Diptheria ("extinct" in US, present in developing countries)
West Nile Virus
CMV polyradiculopathy
critical illness myopathy
critical illness neuropathy

AIDP atypical forms and mimics PT I

Levin KH. Variants and mimics ocf Guillian Barre Syndrome.The Neurologist 2004;10:61-74

typical case AIDP: febrile antecedent esp. campylobacter jej, CMV, EBV, infl, mycoplasma, coxsackie, hepatitis virus. Other noninfectious causes include Hodgkins dis, and events such as surgery, childbirth, and immunization. Within 2 weeks, get symmetric leg paresthesiae, tingling, crawling sensations, pain esp in back (50%), ascending weakness. 50 % develop weakness diaphragmand cranial nn. > 50 % have autonomic findings. CSF dissociation acellularity, increased protein, and typical NCS (not detailed here).
Variants: asymmetric; pure motor; prominent sensory loss; preserved DTR's; regional presentations (pharyngeal/brachial/cervical); paraparetic; facial diplegia with paresthesias; pure sensory neuropathy; pure autonomic neuropathy; Miller Fisher variant; axon loss variants (AMAN, AMSAN).
Miller Fisher syndrome-- triad opthalmoplegia, areflexia, ataxia (follows sensory loss). NCS show loss of SNAP amplitude. Course is often benign,maynot require IVIG/Plasmapx. may include facial weakness, dysarthria, dysphagia, abnormal pupils, limb weakness. 95 % have ANTI GQ1B antibodies.
AMAN-- Chinese disease-- NCS show motor amplitude loss without demyelination. High correlation with campylobacter. Antibodies to GD1a and GM1 at node of Ranvier. Involves complement activation and macrophage infiltration.
AMSAN-- cannot differentiate from AMAN until enough time has elapsed to show NCS findings. Typically this does not respond to IVIG/plasmapx.

tick paralysis-- notoriously overlooked in children, esp preadolescent girls. Ticks may infest scalp. Symptoms develop 2-4 days later including paresthesias, gait ataxia, diplopia, dysarthria, rapid weakness. Tick is dermocenter andersonii. Paralysis reverses within 24 hours of tick removal. Australian ticks cause paralysis that lasts longer. NCS show reduced CMAP amplitudes.

marine toxins-- ciguatoxin (diflagellates eaten by algae), tetrodotoxin (pufferfish) and saxitoxin
(dinoflagellates eaten by shellfish)cause paresthesias and weakness within hours. NCS show slow motor/sensory responses (mimics GBS) and dispersed CMAP.

buckthorn berry-- in SW USA and Mexico. Affects children and cattle causing rapid weakness within a few weeks. Limited amt published.

heavy metals (esp arsenic, gold, thallium).
Arsenic-- 7-14 days after ingestion. presents with N/V/D paresthesias, burning, then stocking glove loss small and large fibers. Weakness is distal to proximal and lead to footdrop. Predominant axon loss, Occassional ans dysfunction.
Gold-- usually secondary to RA treatment. PN, with pain, may be sudden or slow, with or without dermatitis and stomatitis.
Thallium-- usually deliberate ingestion (may be accidental in kids) or due to mal intent. Causes dermatitis, alopecia (usually a LATE finding), GI (N/V/D), CNS (ON, confusion, movement disorders, psych), acute and chronic PN. Starts with painful paresthesias and painful joints, ascending weakness, possibly normal DTR's, autonomic dysfunction

Saturday, January 06, 2007

CNS complications of HPCT

Denier et al. Spectrum and prognosis of neurologic complications after hematopoeitc transplantation. Neurology 2006;67: 1990-1997.

Modern study. Ablation of bone marrow with allogeneic grafts are treated with prophylaxis against previously common events such as veno-occlusive disease and pulmonary complications. Now neurologic disease is a major cause of M/M. They occurred in about 16 % of patients receiving HPCT, usually opportunistic infections. Toxoplasmosis was the most common cause (33%) with others getting viral encephalitis, HSVE, and less commonly, metabolic encephalopathy, stroke, peripheral nervous system dysfunction.

Spinal epidural abscess

Darouiche RO. Current Concept: Spinal epidural abscess NEJM 35;19 2012 Nov 9 2006

Article concentrates on bacterial causes. Most patients have predisposing risk factors: DM, ETOH, HIV, drug abuse intravenous, DJD, surgery with instrumentation, placement of stimulators, or potential local source of infection (skin, soft tissue, indwelling catheter, UTI, sepsis). Entry is contiguous spread (1/3) or hematogenous (1/3). Two thirds are staph aureus, 40 % of those Methicillin resistant (MRSA). These are especially common a few weeks after implantation of devices.

Other causes: St epidermidis, e coli, Ps aer., rarely actinomyces, nocardia, mycobacteria, fungi, (candida, aspergillus) parasites (echonococcus and dracunculus). A letter writer added brucellosis as a cause in Spain, Italy and the Near East.

Spinal cord injury can occur either by mechanical compression of vascular occlusion due to septic thrombophlebitis.

Clinical staging system: stage 1, back pain at level; stage 2, nerve root pain of affected level; stage 3, motor weakness, sensory loss, or B/B dysfunction at affected level; stage 4, paralysis. 3/4 have back pain, fever present in half, neurologic dysfunction in one third. Stage 2 is "enigmatic" in thoracic cases. Duration/rate of progression is highly variable but can be extremely rapid.

Abscesses favor large epidural spaces with infection prone fat, and therefore are more common in posterior than anterior and thoracolumbar than cervical. Lumbar even more common due to epidural injections. Generally they extend over 3-4 levels or more.

Diagnosis is by drainage. Sed rate is always high. Differential diagnostic conditions ( osteomyelitism discitis, sepsis, endocarditis) also have S aureus bacteremia. CSF cultures are negative in 75%. Blood cultures are usually positive. Risks of LP includes causing meningitis by introducing infection through the meninges or causing deterioration if tapped below a block.

MRI with contrast is preferred procedure although myelography has > 90 % sensitivity. Spine CT can be done in conjunction with and may suggest changes of osteopmyelitis.

Frequent misdiagnoses include: osteomyelitism discitis, meningitis, UTI, sepsis, endocarditis, disc prolapse, DJD, spinal tumor, transverse myelitis, spinal hematoma. These are made because patient is neurologically intact.

Treatment: medical v. surgical. No trials done. Medical treatment indicated if patient has high risk of surgery, has panspinal infection, or paralysis for more than 24 hours, or if agent is identified and his condition is monitored closely. Surgery can be a limited laminectomy if patient has a panspinal infection. Empiric coverage should include coverage against MRSA, against gram negative bacilli (with a third or fourth generation cephalosporin such as ceftazidime). Letter writer added that medical management was safe as long as the patient didnot deteriorate.

Statistics: 4-22% get irreversible paralysis. 11-75 % are initially misdaignosed.

The most important predictor of outcome is patient's status just before surgery. Patients who undergo surgery in stage 1 or 2 are expected to remnain neurologically intact.