1. Date of download: 9/18/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Craniocerebral Magnetic Resonance Imaging Measurement and Findings in Lesch-Nyhan Syndrome Arch Neurol. 1998;55(4):547-553. doi:10.1001/archneur.55.4.547 A, Axial T 1 -weighted SPGR (SPoiled GRASS-Gradient Refocused Acquisition in the Steady-State) image of a patient with Lesch- Nyhan syndrome (LNS) (patient 2; aged 22 years) shows prominent frontal horns, caused by lack of the normal prominent bulging of the caudate heads into the ventricles. The caudate nuclei are small, and the bicaudate distance is large, measuring 1.12 cm at the level of the foramina of Monro. B, Axial T 1 -weighted SPGR image of a patient with LNS (patient 1; aged 19 years) also shows prominent frontal horns, caused by lack of the normal prominent bulging of the caudate heads into the ventricles. The caudate nuclei are small, and the bicaudate distance is large (1.03 cm). Also present is prominence of the frontal sulci and subarachnoid spaces. C, Axial T 1 -weighted SPGR image of a healthy volunteer (aged 25 years) shows the normal thin configuration of the frontal horns, resulting from lateral impression of the caudate heads into the ventricles. These normal caudates (arrow) are larger and more full and rounded than in the 2 patients with LNS. Bicaudate distance is 0.8 cm. Figure Legend:

2. Date of download: 9/18/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Craniocerebral Magnetic Resonance Imaging Measurement and Findings in Lesch-Nyhan Syndrome Arch Neurol. 1998;55(4):547-553. doi:10.1001/archneur.55.4.547 A, Midline sagittal T 1 -weighted image of a patient with Lesch-Nyhan syndrome (LNS) (patient 2; age 22 years) shows a diffusely small brainstem, with a very prominent prepontine cistern (arrows), and a slightly large cerebellomedullary cistern posterior to the brainstem. The corpus callosum appears slightly rounded, and short in rostral-caudal extent. B, Midline sagittal T 1 -weighted image of a healthy volunteer (age 23 years) shows the normal appearance of a brainstem that fills the cranial base, with a normal-sized prepontine cistern, much smaller than in the patient with LNS. Figure Legend:

3. Date of download: 9/18/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Craniocerebral Magnetic Resonance Imaging Measurement and Findings in Lesch-Nyhan Syndrome Arch Neurol. 1998;55(4):547-553. doi:10.1001/archneur.55.4.547 A, Parasagittal T 1 -weighted image of a patient with Lesch-Nyhan syndrome (LNS) (patient 2; aged 35 years) showing prominent hyperpneumatization of the frontal sinus, including aeration of a supraorbital extension of the sinus (black arrow). Note the thickening of the skull marrow, which demonstrates an abnormal somewhat dark signal (white arrow). B, Parasagittal T 1 -weighted image of a healthy volunteer (aged 24 years) showing a normal thin strip of normal bright fatty marrow (white arrow). Also, the normal pneumatization of the frontal sinus is contrasted with the hyperpneumatization in the patient with LNS. Figure Legend:

4. Date of download: 9/18/2016 Copyright © 2016 American Medical Association. All rights reserved. From: Craniocerebral Magnetic Resonance Imaging Measurement and Findings in Lesch-Nyhan Syndrome Arch Neurol. 1998;55(4):547-553. doi:10.1001/archneur.55.4.547 Volumetric magnetic resonance imaging measures for caudate and putamen are contrasted with age-matched control subjects (NOR). The significant reduction in caudate volume in patients with Lesch-Nyhan syndrome (LNS) is demonstrated. Figure Legend: