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|LETTERS TO EDITOR
|Year : 2019 | Volume
| Issue : 3 | Page : 881-883
Decerebrate rigidity with preservation of consciousness in pontine hemorrhage with complete neurologic recovery
Boby V Maramattom, Siddharth Bhattacharjee
Department of Neurology, Aster Medcity, Kothad, Kochi, Kerala, India
|Date of Web Publication||23-Jul-2019|
Dr. Boby V Maramattom
Department of Neurology, Aster Medcity, Kothad, Kochi - 682 006, Kerala
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Maramattom BV, Bhattacharjee S. Decerebrate rigidity with preservation of consciousness in pontine hemorrhage with complete neurologic recovery. Neurol India 2019;67:881-3
|How to cite this URL:|
Maramattom BV, Bhattacharjee S. Decerebrate rigidity with preservation of consciousness in pontine hemorrhage with complete neurologic recovery. Neurol India [serial online] 2019 [cited 2020 Sep 23];67:881-3. Available from: http://www.neurologyindia.com/text.asp?2019/67/3/881/263170
The term “decerebrate rigidity” (DR) was first used in 1898 by Sherrington to describe the posture after an intercollicular transection in animals—i.e., a lesion between the red nuclei and vestibular nuclei. This resulted in the loss of upper limb flexor modification normally supplied by the rubrospinal tracts (RuST) and exaggerated extensor reflexes (facilitated by the descending lateral vestibulo-spinal and medial reticulo-spinal pathways) causing rigid extension of the limbs with hyper-reflexia and opisthotonus.
DR in humans is often caused by severe brainstem injury and is associated with coma and severe motor dysfunction. There are only a handful of case reports of DR in conscious patients with pontine lesions, and all these patients had a poor neurological outcome.,, We describe a young man with familial cavernous cerebral malformations (CCM) with DR and preserved consciousness, who made a complete neurological recovery.
A 16-year old boy presented to the emergency department (ED) with slurring of speech and dysphagia for 3 days. On the next day, it progressed to anarthria. His father and brother had multiple CCMs.
On examination, he was conscious, anarthric, and unable to open his mouth or protrude his tongue. He had distal upper limb weakness with normal lower limb power and bilateral cerebellar signs. Deep tendon reflexes were brisk with extensor plantar responses. Sensory examination was normal. His magnetic resonance imaging (MRI) showed a large pontine hemorrhage with multiple scattered type 4 CCMs [Figure 1]
|Figure 1: (a) Blue squares show the location of corticospinal tracts. Orange squares show the RuST. (b and c) Brainstem CCM in axial sections at the pons and pontomesencephalic areas. (d-f) DTI fiber tracking images through the pons, midbrain (axial) and the sagittal brainstem|
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In 4 days, he developed a “classic” locked-in state with complete quadriplegia. He was tracheostomized for airway protection. He developed intermittent prolonged tonic decerebrate posturing with trismus, rendering oral suctioning difficult. Each episode lasted for 1–3 h with spontaneous recovery. These episodes were associated with tachycardia, hypertension, and diaphoresis [mimicking paroxsymal autosomal instability with dystonia (PAID)] [Figure 2]. During these episodes, he could communicate by eye movements. Between the episodes, muscle tone normalized and he had mild spasticity in all four limbs with hyper-reflexia. He was treated with antiedema measures. His motor power progressively improved over a month. The episodes of DR slowly diminished over the next 20 days, and after 40 days, he had recovered completely.
The rostral portion of the reticular formation (RF) above the trigeminal nerve entry zone in the pons [ascending reticular activating system (ARAS)] is involved in consciousness.,, In contrast, the caudal portion of the RF is involved in motor and autonomic function and maintenance of tone and posture [the medial reticulospinal tract; (MeRST) and the lateral vestibulospinal tract (LVST)]. These provide excitatory input to the extensor motor neurons of fore and hind limbs and inhibitory input to flexor motor neurons, and are inhibited by supranuclear impulses. Lesions annulling the supranuclear inhibition to these tracts (MeRST and LVST) allows them to exert an undue excitatory influence on extensor muscles of the limbs. In contrast, the inhibitory reticular formation (IRF), which reduces extremity tone, requires modulatory input from the basal ganglia, cerebral cortex, and cerebellum to discharge, is further inhibited by supranuclear lesions.
The corticospinal tracts (CST) and RuST (which extend only till the upper cervical segments) also increase flexor tone in the upper limbs. Therefore, lesions above the midbrain (red nucleus level) produce decorticate rigidity; as an intact RuST in conjuction with the MeRST and LVST cause flexion of the upper limbs and extension of lower limbs. Lesions below the level of red nucleus disrupt the RuST and disinhibit the MeRST and LVST, leading to decerebrate rigidity. By and large, these lesions also disrupt the corticospinal tracts and cause severe neurologic sequalae. MRI diffusion tensor imaging with tractography (DTI) has been used to parcellate the brainstem tracts and demonstrate major tracts including the RuST.
In our patient, a discrete lower pontine hematoma from a CCM interrupted the RuST and resulted in a “classic gamma rigidity” of DR with extension of all four limbs, adduction, hyperpronation of arms, plantar flexion of feet, ophisthotonus, and trismus. As the lesion spared the ARAS, MRST, LVST, and corticospinal tracts, our patient had episodic DR with preserved consciousness and full recovery of motor function. DTI-MRI demonstrated interruption of the mediodorsal tracts in the pons with sparing of the CST. As our case demonstrates, DR in conscious patients can occur due to selective tract involvement in the brainstem sparing critical motor tracts and has a good neurological outcome.
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[Figure 1], [Figure 2]