Unusual Cause of Chorea

By Dr. Stalin RoyM5 unit

Prof. P. Vijayaraghavan’s unit

Background

• A 14 year old boy was brought to the casualty with history of snake bite (Cobra) two hours back.

• Patient had bilateral ptosis and his breathing was laboured.

• Local examination revealed fang marks on his left foot without any local cellulitis or excessive bleeding.

• He was administered Tetanus toxoid and transferred to the Intensive Medical Care Unit.

• Immediately after shifting to the IMCU patient developed cardiac arrest.

• CPR was started.• Within a few chest compressions

patient’s heart beat was restored.• He was intubated and put on ventilator in

volume AC mode.

• Whole blood clotting time was normal. • ASV (8 vials) was started after a test

dose along with inj neostigmine 0.5mg/hrly.

• Patient regained consciousness after 4 hours and was successfully weaned from ventilator over the next 6 hours.

• All the baseline blood investigations were normal.

• The general condition improved and the patient became ambulant the third day.

• He was transferred to the medical ward.

• On the fourth day morning patient woke up with weakness of his right upper and lower limb.

• There was no obvious facial weakness or sensory disturbance or bladder involvement.

• The power was 3/5 in the right upper limb and 2/5 in the lower limb.

• Plantar was extensor on the right side and reflexes were brisk in the right side.

• There was an episode of generalised seizures lasting for 2-3 min during sleep.

CNS examination

Right Left

Upper Limb Lower Limb Upper LimbLower Limb

Bulk Normal Normal Normal Normal

Tone ^ ^ Normal Normal

Power 3 2 5 5

Reflex + ++ + +

Plantar Extensor Flexor

• Higher Mental Function• Conscious • Orientation – time, place, person - normal• Memory – recent & remote - normal• Speech – normal

• Cranial nerves – normal• Motor system:

• Sensory system – normal• Meningeal signs – Nil

• The next day patient developed choreiform moments of the extremities (Left > Right).

Sequence of events

Investigations

• CT brain plain – normal study• MRI brain – normal study• CSF analysis

– Protein 42mg– Sugar 68mg– Acellular

• NCS – normal• Echo - normal

Initial MRI – day 6 (normal)

What is the diagnosis?

Treatment

• Patient was started on inj Methyprednisolone IV and the weakness gradually improved over the next three days and the abnormal movements also disappeared over 7 days.

After 5 days of IV steroids

Repeat MRI

• MRI was repeated after 1 week. • T2 hyper-intensities were noted in

both the caudate nuclei and lentiform nuclei.

MRI after 1 week

Final diagnosis

• Acute Disseminated Encephalomyelitis – ADEM presenting as chorea, following ASV administration.

Follow up

• Recent picture

• Oral steroids were tapered over the next 3 months and now the patient is totally asymptomatic.

After 3 months

Only 2 cases reported in literature

• Fatal acute disseminated encephalomyelitis following treated snake bite in India – Malhotra et al, Emerg Med J 2005;22:308-309 – “We describe the first documented

case of autopsy proven acute disseminated encephalomyelitis following treated snake bite in a young female.”

• Acute Demyelinating Encephalomyelitis After Anti-venom Therapy in Russell’s Viper Bite - S. Tripathy et al J. Med. Toxicol. Volume 6, Number 3, 318-321 dt 17 march, 2010– “Russels viper bite followed by treatment

with antivenom may be complicated by the development of immune complex mediated demyelination and development of acute disseminated encephalomyelitis”

GBS following Snake bite

• Guillain-Barre syndrome following snake bite: An unusual complication. Srivastava A, et al, Ann Indian Acad Neurol 2010;13:67-8– “Till date only one case has been

reported following snake bite; this was from Chinese Taipei in 1996. In this article, we present one such case of GBS following snake bite”.

ADEM

• Acute disseminated encephalomyelitis (ADEM) is a nonvasculitic inflammatory demyelinating condition that bears a striking clinical and pathological resemblance to multiple sclerosis.

Causes

• Acute disseminated encephalomyelitis (ADEM) may develop in the wake of a wide variety of infectious illnesses or immunizations.

• The agents most commonly implicated are Ebstein-Barr virus, cytomegalovirus, herpes simplex virus (HSV), and mycoplasma.

• The hiatus between onset of viral symptoms and onset of ADEM may range from 2-20 days.

• Clear links between the Pasteur rabies vaccine and ADEM have been established.

• Immunizations less frequently associated with ADEM include pertussis, measles, Japanese B virus, tetanus, and influenza.

Clinical features

• The first signs of ADEM usually include abrupt onset of irritability and lethargy (>94% of cases).

• Changes in mental status (88% of cases) are commonly observed in ADEM.

• Convulsive seizures occur around the onset of ADEM in as many as 25% of cases.

• Although almost any portion of the CNS may be clinically involved, the descending white matter motor tracts, optic nerves, and spinal cord are particularly commonly involved

• A wide variety of cranial nerve abnormalities may occur in addition to optic nerve disease.

• Long tract signs (eg, clonus, increased muscle stretch reflexes, upgoing toes) are present early in as many as 80% of cases.

• In some instances, reflexes may be lost at the onset. But the evolution of disease after spinal shock replaces absent reflexes with increased muscle stretch reflexes within a few days.

• Weakness may be hemiparetic, double hemiparetic, diaparetic, or generalized and symmetric.

MRI findings

• T2-weighted, MRI disclose characteristic high-signal lesions in more than 80-90% of cases of ADEM.

• ADEM lesions are characteristically centrifugal at the junction of the deep cortical gray and subcortical white matter.

• Additional lesions may be found in deeper white matter, optic nerves, basal ganglia (30-40%), the thalamus (30-40%), the brainstem (45-55%), the cerebellum (30-40%), and the spinal cord.

MRI differentials

• ADEM lesions tend to have a "smudged" edge rather than the crisp margin typical of the classic ellipsoid plaques of MS.

• ADEM lesions may contain areas of hemorrhage mimicking HSV2 encephalitis.

• Ring enhancement or mass effect sometimes found in ADEM may mimick abscess or tumor.

• No changes on MRI are pathognomonic of ADEM or for that matter of demyelination.

Initial MRI may be normal !!

• Some patients with ADEM have normal findings on MRI on initial presentation that become abnormal and characteristic of ADEM if the study is repeated several weeks later, even though patients are then showing clinical improvement.

• This suggest that normal findings on a scan do not exclude the ADEM diagnosis, and that the appearance of new lesions during recuperation from ADEM may not represent recrudescence of disease.

Other tests

• The EEG may show Focal or generalized slowing, sharp waves, rhythmic delta, or spikes may be found in the waking state during the early stages of ADEM.

• The lumbar puncture is an essential aspect of acute disseminated encephalomyelitis (ADEM) workup. It assists in distinguishing ADEM from various forms of meningoencephalitis, especially upon the basis of titers for the various bacteria, viruses, or other agents that may produce a directly infectious form of meningoencephalitis.

Treatment

• ADEM is often treated with high-dose intravenous corticosteroids, to which it appears to be responsive.

• One common protocol is 20 mg/kg/d of methylprednisolone (maximum dose of 1 g/d) for 3-5 days. Improvement may be observed within hours but usually requires several days.

• An oral taper for 3 weeks or some other interval is sometimes appended.

• The chief alternative therapy is intravenous immune globulin (IVIG).

Complications

• Acute hemorrhagic leukoencephalitis, which is at the severe end of the spectrum of ADEM-like illnesses, may be observed in certain infectious illnesses such as measles encephalitis. It has mortality of 70%.

• Recurrence is the chief outpatient complication of ADEM, however it is rare.

Summary

• ADEM presents as acute onset poly symptomatic neurological dysfunction following triggering event such as infection or vaccination.

• Imaging shows multifocal white and grey mater lesions in brain and spinal cord.

• Clinical examination, MRI and CSF analysis are most useful in establishing diagnosis.

• Corticosteroids are the mainstay of treatment.

MRS findings

• Quantitative proton MR spectroscopic imaging has shown low N-acetylaspartate (NAA) and high lactate levels in acute lesions, which normalize after recovery.

HIE

• Clinical features:– The most common pattern of injury in HIE is selective

loss of sensitive neurons(pyramidal cells of CA1 of the hippocampus, layers 3, 5, and 6 of the neocortex, Purkinje cells, and striatal neurons)

– Bilateral hippocampal damage causesKorsakoff's amnesia. This is a memory disorder characterized by inability to retain new information (anterograde amnesia) and a less severe defect of recall of old memories (retrograde amnesia). Hippocampal amnesia (Korsakiff's amnesia) affects more severely episodic memory and less so semantic memory.

– Diffuse cortical, thalamic, or combined neuronal loss (with intact brainstem) results in dementia or the persistent vegetative state (loss of cognitive functions and emotion with preservation of sleep-wake cycles, autonomic function, and breathing)

• White matter in HIE:– Acute HIE damages primarily neurons of the cerebral

cortex and deep nuclei. The white matter is only rarely affected. One exception is CO poisoning.

– Leukoaraiosis(rarefaction of the white matter) is a neuroradiology term describing the loss of density of the white matter on CT and increased signal on T2 or FLAIR MRI. These findings can be explained by loss of myelin and axons and increased interstitial fluid. Leukoaraiosis is probably due to the chronic effect of microvascular disease associated with hypertension, diabetes, and angiopathies.