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Transthecal digital block: Flexor tendon sheath used for anesthetic infusion
Transthecal digital block: Flexor tendon sheath used for anesthetic infusion A new approach to achieve diital block by use of the flexor tendon sheath as an avenue introducing anesthetics to the core of the digit is described. Through centrifugal anesthetic dIusion all four digital nerves are anesthetized rapidly. This technique involves palmar percutaneous iqjection of 2 ml of Iidocaine (Xyloeaine) into the potential space of the Bexor tendon sheath at the level of the palmar flexion crease with a 3 ml syringe and a No. U-gauge hypodermic needle. Over the last 5 years, I have used this technique on 420 patients with no observable anesthetic complication. A repeat iqjection or local infiltration as a supplement was necessary only in four instances. (J HANDSURGWJO;15A:471-3)
David
T. W. Chiu, MD, FACS, New York, N.Y.
C
onventional digital nerve block techniques required multiple injections of anesthetics for each digit.’ Ring block or bilateral digital nerve block in the tightly confined space at the base of the phalanges is hazardous, inasmuch as gangrene of the finger resulting from such nerve block has been reported.2‘4 During the treatment of trigger finger by the injection of a mixture of steroid and lidocaine (Xylocaine) into the flexor tendon sheath at the metacarpophalangeal joint level, I was impressed with the rapid onset of anesthesia involving the entire digit. Dissection of 10 cadaveric fingers after percutaneous injection of the flexor tendon sheath with 10% methylene blue showed a complete staining of the entire flexor tendon sheath and centrifugal diffusion of the blue dye circumscribing the entire circumference of the proximal phalanx. The palmar, ulnar, and radial digital nerves, the dorsal, ulnar, and radial digital nerves, branches of the superficial radial nerve, and the dorsal branch of the ulna nerve were completely stained (Figs. 1 through 3). On the From the Department of Plastic Surgery, Institute of Reconstructive Plastic Surgery, New York University Medical Center, New York, N.Y. Received for publication 16, 1989.
Jan. 13, 1989; accepted in revised form May
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint requests: David T. W. Chiu, MD, FACS, Atchley Pavillion, Columbia-Presbyterian Medical Center, 161 Port Washington Ave, New York, NY 10032. 3/l/14460
Fig. 1. Transthecal injection of 10% methylene blue leads to complete staining of the flexor tendon sheath. In this cadaveric dissection, the left small and long fingers were injected with 2 ml of 10% methylene blue. Subcutaneous tissue staining around the flexor tendon sheath of these fingers was clearly observable. The flexor tendon sheath and the subcutaneous space of the ring finger were spared.
THE JouRNfi
OFHANDSURGERY
471
472
Chiu
Fig. 2. Same specimen as Fig. 1. The methylene blue dye diffused into the subcutaneous space and egressed into the epiaponeurotic plane of both injected digits (right long and small fingers). The epiaponeurotic space of the ring finger was not involved.
I have used this transthecal digital block technique to achieve digital anesthesia in 420 cases over the last 5 years. This technique has the unique advantages of: 1. Requiring a single injection for anesthesia of the entire digit; 2. Requiring a relatively small volume of anesthetic agent, in most cases 2 ml of anesthetic; 3. The onset of anesthesia is rapid. Adequate anesthesia as a rule appears within 3 to 4 minutes of the injection. 4. There is no risk of direct mechanical trauma to the neurovascular bundle as compared with the conventional distal nerve block technique involving the injection of anesthetic around the neurovascular bundle directly.
basis of these observations
Technique Preparation. The hand to be anesthetized should be prepared with povidone-iodine (Betadine) then with alcohol. The index finger of the operator should be prepared in the same manner.
The Journal of HAND SURGERY
Fig. 3. A single, cadaveric digit preparation (right, long) demonstrating dye infiltration of the epineurium of the palmar radial digital nerve and its dorsal branch.
Localization of the flexor tendon. With the patient’s hand fully supinated and the digit flexed and extended gently, the flexor tendon can be palpated readily as it glides over the protuberance of the metacarpal head. After the flexor tendon is localized, it may be marked with a skin pencil (Fig. 4). Injection of anesthetic. It is recommended that a 3 ml syringe with a No. 25gauge needle be used to introduce the anesthetic. Penetration of the skin should be made sharply through the subcutaneous tissue and down to the flexor tendon sheath. With experience, as the flexor tendon sheath is penetrated, the difference in tissue consistency can often be felt. If the penetration has overshot, the flexor tendon would be entered. The characteristic tissue consistency of the tendon will alert the operator to the fact that the needle point has passed the flexor tendon sheath. The operator should then exert gentle pressure on the plunger as he or she withdraws the needle ever so gently and gradually. As the needle leaves the substance of the tendon and lies in the potential space between the flexor tendon sheath and the tendon substance, an abrupt inflow of the anesthetic
Vol. lSA, No. 3 May 1990
will occur. At this juncture the patient often reports that the finger feels somewhat blown up. Objectively, when one observes the injected digit it exhibits a momentary and slight proximal interphalangeal joint extension. After completion of the injection the needle is withdrawn. With the operator’s index finger pressing down on the flexor tendon proximal to the metacarpophalangeal joint crease the flow of anesthetic will be directed distally, and the bulging of the flexor tendon sheath can be clearly felt. Pressure is applied to the injection site for 2 to 3 minutes. Within 1 minute after injection, a warm sensation develops in the injected digit. Within 2 minutes pin and needle sensibility persists but the light touch sensibility is dampened. Adequate anesthesia is expected in 3 to 5 minutes. In a 5-year period, beginning in 1982, I have used the transthecal digital block technique in the following group of cases: excision of soft tissue tumors (75), nail bed repairs (67), wound debridement (50), removal of foreign body (38), pinning of distal interphalangeal joint (37), pinning of proximal phalanx (36), repair of lacerations (36), repair of digital nerves (28), pinning of proximal interphalangeal joints (26), repair of extensor tendon (13), pinning of middle phalanx (12), reattachment of amputated long finger, distal to FPS insertion (2). Repeated injection or local injection as a supplement was necessary in four instances. In three of the four instances, the digit involved was the thumb. The remaining one initial failure involved the index finger. In all instances, satisfactory anesthesia was ultimately achieved. There were no reported or detected complications arising from application of this anesthesia technique.
Discussion As compared with other methods of achieving anesthesia of the fingers, this method requires only one injection, whereas multiple injections are required if the digital nerves are to be blocked by a conventional metacarpal block. As compared with the wrist block technique for the ring finger for instance, complete anesthesia of the ring finger requires blocking of the median and ulnar nerves, as well as the dorsal branch of the ulnar nerve. This requires the injection of anesthetic at three different anatomic sites. The advantage of a single injection is most conspicuous in treatment of children. However, great care must be taken to adhere to sterile techniques in employing this anesthetic method, inasmuch as contamination of the flexor tendon sheath would be disastrous. In addition, the needle applied must be of small caliber, namely, No. 25- or No. 27-
Transthecal digital block
473
Fig. 4. Anatomical landmark of the injection site. The flexor tendons are palpable as they pass palmar to the metacarpal head prominence. The section of the flexor tendon sheath slightly proximal to the metacarpophlangeal joint is chosen as the danger site for penetration to avoid injury of the A2 pulley (black dot). Gentle pressure is exerted over the flexor tendon sheath proximal to the metacarpophalangeal joint to assure a distally directed flow of anesthetic agent.
gauge needles. A larger caliber might cause substantial damage to the flexor tendon and is deemed unacceptable. Application of gentle pressure at the site of injection after the needle is withdrawn will minimize bleeding and is mandatory. This method should not be used if the patient is receiving anticoagulant therapy or has an untreated coagulationapathy. REFERENCES Ramamutthy S. Anesthesia. In: Green DP, ed. Operative hand surgery 2. New York: Churchill Livingstone, 1982:41. Abadir A. Anesthesia for hand surgery. Grthop Clin North Am 1970;1:205. Sandzen SC. Treating acute hand injuries. Am Fam Physician 1974;9:74-97. Beasley RW. Hand injuries. Philadelphia: WB Saunders, 1981:58.
David
T. W. Chiu, MD, FACS, New York, N.Y.
C
onventional digital nerve block techniques required multiple injections of anesthetics for each digit.’ Ring block or bilateral digital nerve block in the tightly confined space at the base of the phalanges is hazardous, inasmuch as gangrene of the finger resulting from such nerve block has been reported.2‘4 During the treatment of trigger finger by the injection of a mixture of steroid and lidocaine (Xylocaine) into the flexor tendon sheath at the metacarpophalangeal joint level, I was impressed with the rapid onset of anesthesia involving the entire digit. Dissection of 10 cadaveric fingers after percutaneous injection of the flexor tendon sheath with 10% methylene blue showed a complete staining of the entire flexor tendon sheath and centrifugal diffusion of the blue dye circumscribing the entire circumference of the proximal phalanx. The palmar, ulnar, and radial digital nerves, the dorsal, ulnar, and radial digital nerves, branches of the superficial radial nerve, and the dorsal branch of the ulna nerve were completely stained (Figs. 1 through 3). On the From the Department of Plastic Surgery, Institute of Reconstructive Plastic Surgery, New York University Medical Center, New York, N.Y. Received for publication 16, 1989.
Jan. 13, 1989; accepted in revised form May
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Reprint requests: David T. W. Chiu, MD, FACS, Atchley Pavillion, Columbia-Presbyterian Medical Center, 161 Port Washington Ave, New York, NY 10032. 3/l/14460
Fig. 1. Transthecal injection of 10% methylene blue leads to complete staining of the flexor tendon sheath. In this cadaveric dissection, the left small and long fingers were injected with 2 ml of 10% methylene blue. Subcutaneous tissue staining around the flexor tendon sheath of these fingers was clearly observable. The flexor tendon sheath and the subcutaneous space of the ring finger were spared.
THE JouRNfi
OFHANDSURGERY
471
472
Chiu
Fig. 2. Same specimen as Fig. 1. The methylene blue dye diffused into the subcutaneous space and egressed into the epiaponeurotic plane of both injected digits (right long and small fingers). The epiaponeurotic space of the ring finger was not involved.
I have used this transthecal digital block technique to achieve digital anesthesia in 420 cases over the last 5 years. This technique has the unique advantages of: 1. Requiring a single injection for anesthesia of the entire digit; 2. Requiring a relatively small volume of anesthetic agent, in most cases 2 ml of anesthetic; 3. The onset of anesthesia is rapid. Adequate anesthesia as a rule appears within 3 to 4 minutes of the injection. 4. There is no risk of direct mechanical trauma to the neurovascular bundle as compared with the conventional distal nerve block technique involving the injection of anesthetic around the neurovascular bundle directly.
basis of these observations
Technique Preparation. The hand to be anesthetized should be prepared with povidone-iodine (Betadine) then with alcohol. The index finger of the operator should be prepared in the same manner.
The Journal of HAND SURGERY
Fig. 3. A single, cadaveric digit preparation (right, long) demonstrating dye infiltration of the epineurium of the palmar radial digital nerve and its dorsal branch.
Localization of the flexor tendon. With the patient’s hand fully supinated and the digit flexed and extended gently, the flexor tendon can be palpated readily as it glides over the protuberance of the metacarpal head. After the flexor tendon is localized, it may be marked with a skin pencil (Fig. 4). Injection of anesthetic. It is recommended that a 3 ml syringe with a No. 25gauge needle be used to introduce the anesthetic. Penetration of the skin should be made sharply through the subcutaneous tissue and down to the flexor tendon sheath. With experience, as the flexor tendon sheath is penetrated, the difference in tissue consistency can often be felt. If the penetration has overshot, the flexor tendon would be entered. The characteristic tissue consistency of the tendon will alert the operator to the fact that the needle point has passed the flexor tendon sheath. The operator should then exert gentle pressure on the plunger as he or she withdraws the needle ever so gently and gradually. As the needle leaves the substance of the tendon and lies in the potential space between the flexor tendon sheath and the tendon substance, an abrupt inflow of the anesthetic
Vol. lSA, No. 3 May 1990
will occur. At this juncture the patient often reports that the finger feels somewhat blown up. Objectively, when one observes the injected digit it exhibits a momentary and slight proximal interphalangeal joint extension. After completion of the injection the needle is withdrawn. With the operator’s index finger pressing down on the flexor tendon proximal to the metacarpophalangeal joint crease the flow of anesthetic will be directed distally, and the bulging of the flexor tendon sheath can be clearly felt. Pressure is applied to the injection site for 2 to 3 minutes. Within 1 minute after injection, a warm sensation develops in the injected digit. Within 2 minutes pin and needle sensibility persists but the light touch sensibility is dampened. Adequate anesthesia is expected in 3 to 5 minutes. In a 5-year period, beginning in 1982, I have used the transthecal digital block technique in the following group of cases: excision of soft tissue tumors (75), nail bed repairs (67), wound debridement (50), removal of foreign body (38), pinning of distal interphalangeal joint (37), pinning of proximal phalanx (36), repair of lacerations (36), repair of digital nerves (28), pinning of proximal interphalangeal joints (26), repair of extensor tendon (13), pinning of middle phalanx (12), reattachment of amputated long finger, distal to FPS insertion (2). Repeated injection or local injection as a supplement was necessary in four instances. In three of the four instances, the digit involved was the thumb. The remaining one initial failure involved the index finger. In all instances, satisfactory anesthesia was ultimately achieved. There were no reported or detected complications arising from application of this anesthesia technique.
Discussion As compared with other methods of achieving anesthesia of the fingers, this method requires only one injection, whereas multiple injections are required if the digital nerves are to be blocked by a conventional metacarpal block. As compared with the wrist block technique for the ring finger for instance, complete anesthesia of the ring finger requires blocking of the median and ulnar nerves, as well as the dorsal branch of the ulnar nerve. This requires the injection of anesthetic at three different anatomic sites. The advantage of a single injection is most conspicuous in treatment of children. However, great care must be taken to adhere to sterile techniques in employing this anesthetic method, inasmuch as contamination of the flexor tendon sheath would be disastrous. In addition, the needle applied must be of small caliber, namely, No. 25- or No. 27-
Transthecal digital block
473
Fig. 4. Anatomical landmark of the injection site. The flexor tendons are palpable as they pass palmar to the metacarpal head prominence. The section of the flexor tendon sheath slightly proximal to the metacarpophlangeal joint is chosen as the danger site for penetration to avoid injury of the A2 pulley (black dot). Gentle pressure is exerted over the flexor tendon sheath proximal to the metacarpophalangeal joint to assure a distally directed flow of anesthetic agent.
gauge needles. A larger caliber might cause substantial damage to the flexor tendon and is deemed unacceptable. Application of gentle pressure at the site of injection after the needle is withdrawn will minimize bleeding and is mandatory. This method should not be used if the patient is receiving anticoagulant therapy or has an untreated coagulationapathy. REFERENCES Ramamutthy S. Anesthesia. In: Green DP, ed. Operative hand surgery 2. New York: Churchill Livingstone, 1982:41. Abadir A. Anesthesia for hand surgery. Grthop Clin North Am 1970;1:205. Sandzen SC. Treating acute hand injuries. Am Fam Physician 1974;9:74-97. Beasley RW. Hand injuries. Philadelphia: WB Saunders, 1981:58.