Neurology India, Vol. 58, No. 2, March-April, 2010, pp. 306-308
Transient alien limb phenomenon in right frontoparietal infarction
Department of Neurology, St. Stephen's Hospital, Delhi, India
Correspondence Address: Samhita Panda, Department of Neurology, Sir Gangaram Hospital, Rajinder Nagar, New Delhi-110060, India, email@example.com
Date of Acceptance: 24-Sep-2009
Code Number: ni10077
AbstractAlien limb phenomenon is associated with different neurological disorders, such as stroke and corticobasal degeneration. It is usually caused by involvement of the corpus callosum, with or without the frontal regions. Rarely, it can result from insult in the posterior cerebral artery territory. Alien limb phenomenon is generally persistent. Here, an unusual case of transient alien hand phenomenon is reported.
Keywords: Alien limb, cerebral infarction, frontoparietal region, stroke
The alien hand sign (AHS) was first described by Brion and Jedynak as a "feeling of estrangement between the patient and one of his hands"  and comprises failure to recognize ownership of one′s limb when visual cues are removed, a feeling that one body part is foreign, personification of the affected body part and autonomous activity, which is perceived as beyond voluntary control.  The combination of perception of a hand being foreign along with involuntary, extravolitional motor activity constitutes the AHS and may be associated with limb apraxia, intermanual conflict and self-restriction. AHS is mostly localized to lesions of the left mesial frontal region and corpus callosum  and has been described in association with several neurological disorders, including corticobasal degeneration, stroke  and Cruetzfeld Jacob disease.  We describe a rare case of transient AHS in a patient with nondominant anterior circulation ischemia.
A 68-year-old, right-handed gentleman presented with sudden onset of abnormal involuntary movements of the left upper limb. While relaxing after dinner, he had felt that his right hand was being touched by someone else. He thought that it was his wife trying to call him. On looking at his right hand, he noted that his left upper limb was groping and trying to hold his right hand. However, he was not able to perceive the left upper limb as his own. His daughter-in-law brought to his attention that it was his own left hand that was trying to grasp objects and the limb was lifted abnormally into space. He could not experience any control over the movements of the left upper limb. He had no difficulty in vision, speech, swallowing, weakness or numbness of the limbs or clumsiness of gait. No headache, vomiting, vertigo or loss of consciousness was observed. He was hypertensive, on regular medication and used to take alcohol occasionally. There was no family history of similar illness.
On arrival at the hospital, feeling of unfamiliarity of the left upper limb persisted, although he could control some movements. He was conscious and oriented to his surroundings. He looked anxious and perturbed. The pulse was 88/min, blood pressure 140/80 mmHg and there was no carotid bruit. Speech was normal. There was no diminution in visual acuity or field defects. There were no cranial nerve palsies. There was abnormal levitation of the left upper limb. The patient was able to recognize his left side of the body and body parts, although there was a sense of disowning of the left upper limb. He could use his limb for bimanual tasks and did not have any apraxia. The left upper limb was hypotonic, but power was normal in all extremities. All deep tendon jerks were normal. Plantar response was bilaterally downgoing. All sensory modalities were absent over the left upper limb and moderately decreased over the left lower limb. There was no hemispatial or visual neglect. Alien limb signs persisted for about 2 h. Subsequently, the patient felt that all his symptoms had subsided and he could have complete control and also could recognize the left upper limb. Neurological examination at this stage revealed persistent hypotonia and sensory loss on the left side. Additionally, mild incoordination of the left upper limb on finger nose test was noted.
Blood biochemistry and complete blood picture were normal. Serum homocysteine level was 17.7 mg/dl. Non-contrast-enhanced computed tomography (CT), performed within 2 h was normal [Figure - 1]. Magnetic resonance imaging (MRI) of the brain showed an altered signal intensity in the right frontoparietal region, which was hypointense on the T1-weighted sequence [Figure - 2]a and hyperintense on the T2-weighted and fluid attenuation and inversion recovery (FLAIR) sequences, with swelling of the adjacent gyri. The same region showed restriction on diffusion-weighted images, suggesting acute right frontoparietal infarct [Figure - 2]b. Electroencephalography showed no epileptiform activity. Electrocardiography and 2-D echocardiography were normal. Carotid and vertebral doppler examination was normal. The patient was treated with antiplatelet medication and statin. He subsequently improved and was asymptomatic at the time of follow-up.
Alien limb phenomenon is usually noted in patients with established stroke and generally occurs later in the course the disease. It is most frequently reported in the anterior cerebral  or posterior cerebral artery territory strokes.  Most often it is a sign that persists for some time and then gradually disappears over 6-12 months.  This report exemplifies a case of alien hand phenomenon occurring transiently as a manifestation of ischemic stroke involving the nondominant, right frontoparietal region.
Three distinct forms of AHS have been described in the literature. , Frontal AHS results from insult to supplementary motor area, anterior cingulate gyrus and medial prefrontal cortex of the dominant hemisphere and anterior corpus callosum.  It involves the dominant limb with increased exploratory reflexes due to release from nondominant hemispheric inhibition. There is involuntary groping, grasping and compulsive manipulation. Callosal AHS results from damage to the anterior corpus callosum with or without bilateral frontal lesions  and results in hemispheric disconnection leading to intermanual conflict during tasks requiring dominant hemispheric control. Rarely, a mixed frontal and callosal AHS has been reported.  The more recently described posterior AHS  usually involves the nondominant thalamus, basal ganglia, occipital and inferior parietal region with or without sparing of the corpus callosum. There is denial of ownership of the nondominant limb and involuntary limb movements that seem to be controlled externally. This may be attributed to sensory impairment, visual field defects and spatial neglect.
The patient described here had a nondominant frontoparietal infarct involving the superior division of the right middle cerebral artery. In him the alien limb phenomenon could be attributed to the profound sensory loss, despite no hemineglect. The involuntary limb utilization, levitation and unfamiliarity of limb, as seen in frontal AHS, were seen without other signs of hemispheric disconnection, such as intermanual conflict and apraxia, noted in the callosal type of AHS. Interestingly, alien limb phenomenon was noted in the upper limb alone even though there was sensory loss in the lower limb. This may be due to the predominant involvement of the hand area of the sensorimotor homunculus, as documented in the MRI. There are only anecdotal reports of such sensory AHS after isolated parietal stroke. 
In our patient the highlighting point is that the phenomenon lasted for only 2 h, after which the patient was subjectively normal. However, subsequent examination revealed persistent sensory deficits. This is unlike the usual description of AHS as a persistent event in stroke, lasting 6-12 months.  There are only two reports of this rare phenomenon. , Such transient phenomenology may be either due to the ongoing ischemia or a sensory seizure.  In our patient AHS probably was a result of on going ischemic injury during the initial phase of evolving stroke. This could have been better substantiated by demonstrating perfusion and diffusion mismatch. In our case the CT scan done at 2 h was essentially normal and the MRI showed acute parietal infarct. The possibility of the phenomenon being a seizure was very unlikely. The type of bizarre motor phenomenon observed in our patient is not the usually described motor seizure semiology and also in our patient the EEG was unremarkable. Our patient also emphasizes the point that acute and short-lasting presentation of this phenomenon should not be interpreted as malingering or dissociative motor disorder. Such patients should be carefully evaluated and managed appropriately.
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