Vishal Garg, MS

Diagram illustrating how autonomic dysreflexia occurs in a person with spinal cord injury. The afferent stimulus, in this case a distended bladder, triggers a peripheral sympathetic response, which results in vasoconstriction and hypertension. Descending inhibitory signals, which would normally counteract the rise in blood pressure, are blocked at the level of the spinal cord injury. The roman numerals (IX, X) refer to cranial nerves.  Mechanism of autonomic dysreflexia in a person with spinal cord injury ( at the level of T6 or above ). An afferent stimulus (e.g., distended bladder or fecal impaction) triggers a peripheral sympathetic response that results in widespread vasoconstriction and subsequent hypertension. Baroreceptors in blood vessels detect this hypertensive crisis and signal the brain via cranial nerve IX and X. Descending inhibitory signals normally respond to counteract the rise in blood pressure with slowed heart rate and vasodilation. However,

(A) Divisional pattern of sensory loss (B) segmental pattern of sensory loss (C) schematic diagram of the trigeminal system in the brainstem The spinal trigeminal nucleus (STN) is the longest cranial nerve nucleus, extending caudally from the medulla to the upper cervical segment 4 of the spinal cord.   Cytoarchitecturally, the STN is divided into three portions  from rostral to caudal: Pars Oralis (from the Pons to the Hypoglossal nucleus/inferior olive) Pars Interpolaris (from the Hypoglossal nucleus/inferior olive to the  obex ) Pars Caudalis (from the obex to C4) The STN has somatotopic arrangement, the central area  of the face is represented by the rostral portion of the STN, and the more outer areas of the face are represented by the caudal portion of the STN. Therefore, lesions invading the subnucleus caudalis cause onion-skin pattern sensory impairment . The onion skin distribution differs from the dermatome distribution of the peripheral branches of t

Hunter’s angle.  ( A) spectra obtained from healthy control in comparison to  ( B) brain tumor --> REVERSAL OF HUNTER'S ANGLE ( C) the posterior gray matter of a patient with Alzheimer’s disease. Hunter's angle (HA)  is a term coined from a neurosurgeon,  C   Hunter Shelden , at Huntington Medical Research Institutes.  He placed his comb on the spectrum at approximately a 45° angle and connected several of the peaks. Hunter's angle is the line formed by the metabolites in  MR spectroscopy . Metabolites  myo- inositol ,  choline ,  creatine , and  N-acetyl aspartate (NAA)  peaks are ascending in a normal spectrum, any alteration in the ascending nature of the peaks means the spectrum is abnormal.