Patients with tremor referred to a Movement Disorder Specialist for evaluation

Inclusion Criteria:

1. Subjects must provide written informed consent prior to the initiation of any study related procedures;
2. Subjects ≥ 40 years of age;
3. Subjects with upper extremity tremor for < 2 years duration.

Exclusion Criteria:

1. Any clinically significant acute or unstable physical or psychological illness based on medical history or physical examination at Visit 1, as determined by the Principal Investigator;
2. Any unexpected clinically significant abnormal laboratory or ECG results obtained at Visit 1 and as determined by the Principal Investigator;
3. Any history of drug, narcotic, or alcohol abuse within 2 years prior to the date of informed consent, as defined by the Diagnostic and Statistical Manual of the American Psychiatric Association, 4th Edition (DSM-IVR {American Psychiatric Association, 1994 #2});
4. Positive urine drug screen at Visit 1;
5. Participation in an investigational drug or device clinical trial within 30 days prior to the date of informed consent;
6. Previous participation in any 123I-ALTROPANE® trial;
7. Any exposure to radiopharmaceuticals within 30 days prior to the date of informed consent;
8. Positive (+) pregnancy test at Visit 1 and/or Visit 2;
9. Breast-feeding;
10. Inability to lie supine for 1 hour;
11. Any significant active thyroid disease;
12. Known sensitivity or allergy to Iodine or Iodine containing products;
13. A history of repeated head injury or sustained severe head injury in year prior to onset of tremor;
14. A definitive diagnosis of encephalitis;
15. Any uncontrolled hypertension or diabetes;
16. Any history of cerebrovascular disease;
17. Previous evaluation by a Movement Disorder Specialist (MDS);
18. Treatment within the previous six (6) months prior to informed consent with bupropion, metoclopramide, cinnarizine, flunarizine, methylphenidate, reserpine, modafinil, alpha methyldopa, amphetamine, or any anti-psychotic medication;
19. Any treatment with anti-Parkinson's drugs or anti-tremor medications within three (3) months prior to the date of the subject signing the informed consent;
20. Any new prescription or change in dose of medications for chronic conditions within four (4) weeks of Visit 2.