The employer/carrier (E/C) appeal an order awarding catastrophic loss benefits. We reverse and remand.
The deputy commissioner (deputy) found claimant to be entitled to catastrophic loss benefits pursuant to § 440.15(2)(b), Fla. Stat. He went on to explain:
I make this finding principally based on the demeanor and testimony of the Claimant as he testified before me. I was able to observe that the Claimant had marked and severe limitations of his right arm. Based on his testimony and my careful observations it is obvious that Claimant has lost the use of his right arm.
Based on my review of the medical records composite, it is uncontradicted that the Claimant did sustain some organic damage to his central nervous system. I specifically take note that Mr. Chaplin had a right C-6 Hemilaminecto-my and Diskectomy with Foraminotomy performed. Dr. St. Louis indicated in his report of December 15 that the Claimant exhibited weakness and sensory changes consimerate [sic] with the surgery. I also make this finding based on my ob*545servations of the Claimant as he testified before me which conclusively demonstrated organic damage to the Claimant’s nervous system.
Whether the loss of use of an arm is the result of organic damage to the nervous system is a question of fact for the deputy. Hernandez v. Equipment Co. of America, 452 So.2d 85 (Fla. 1st DCA 1984). Before the deputy makes any such finding, however, the claimant must demonstrate (1) the total loss of use of an arm (2) because of organic damage to the nervous system. Atlantic Plastering, Inc. v. O’Hara, 454 So.2d 743 (Fla. 1st DCA 1984). The deputy’s findings fall short of satisfying these requirements.
The final order states that claimant was found to have “lost the use of his right arm” and that the existence of organic damage to the claimant’s nervous system was “conclusively demonstrated.” However, the deputy failed to find that claimant had sustained a total loss of use as required by § 440.15(2)(b). If a total loss of use is found, then the deputy must also find that such loss is because of organic damage to the claimant’s nervous system. Hernandez v. Equipment Co. of America, 452 So.2d at 86.
A Deputy’s determination that a claimant has sustained loss of use of his arm because of organic damage to the nervous system cannot be based merely on his observations and the claimant’s demeanor or testimony alone. Loss of use of the arm because of organic damage to the nervous system must be established by medical evidence.
Accordingly, the award of catastrophic loss benefits is reversed and the case is remanded to the deputy for a determination of (1) whether the claimant has sustained a total loss of use of his right arm, and if so, (2) whether such loss is because of organic damage to the nervous system.
Reversed and remanded for further proceedings consistent with this opinion.
BOOTH and SMITH, JJ., concur.