EMERGENCY METHODS AND TECHNIQUES
Nerve Blocks of the Foot Raymond K. Locke, DPM* Philadelphia, Pennsylvania Steven E. Locke, MDt Belmont, Massachusetts
E m e r g e n c y t r e a t m e n t o f f o o t i n j u r i e s c a n b e m a d e l e s s p a i n f u l b y reg i o n a l b l o c k a n e s t h e s i a . T h e r e is l i m i t e d m e d i c a l l i t e r a t u r e o n t h e s e techniques and many physicians, while familiar with regional anest h e s i a o f t h e u p p e r e x t r e m i t y , a r e n o t e x p e r i e n c e d w i t h n e r v e b l o c k s in t h e l o w e r e x t r e m i t y . I n f i l t r a t i o n a n e s t h e s i a of t h e p l a n t a r s t r u c t u r e s of the foot and toes can be very painful and may inhibit healing. Regional anesthesia avoids both of these problems and can prove effective and useful. This paper discusses the techniques and possible complications o f n e r v e b l o c k a n e s t h e s i a o f t h e foot.
Locke RK, Locke SE: Nerve blocks of the foot. JACEP 5:698-702, September 1976. anesthesia, regional, foot; blocks, ankle, a n t e r i o r . . , posterolateral . . . posterior tibial . . . toe; blocks, nerve; drug reactions, adverse; injuries, foot.
INTRODUCTION Patients with foot injuries are most common during summer and vacation periods, in resort or recreat i o n a r e a s , a n d in w a r m c l i m a t e s where people go b a r e f o o t . , A t Tobey Hospital, a s m a l l c o m m u n i t y hospit a l in W a r e h a m , M a s s a c h u s e t t s , a New England coastal resort town n e a r Cape Cod, a total of 7,627 pat i e n t s were e x a m i n e d and t r e a t e d by e m e r g e n c y p h y s i c i a n s from J u l y 1, 1973 to S e p t e m b e r 30, 1973, t h e h e i g h t of t h e s u m m e r v a c a t i o n From the D e p a r t m e n t of Podiatric Surgery,* Riverdell Hospital, Oradelli New Jersey; P e n n s y l v a n i a College of Podiatric Medicine,* Philadelphia, Pennsylvania; and Tobey Hospital,t Wareham, Massachusetts, Department of Psychiatry, Harvard Medical School. McLean Hospital, Belmont, Massachusetts. This paper was supported in part by a grant from Winthrop Laboratories, New York, New York. Address for reprints: Steven E. Locke, MD, McLean Hospital, 115 Mill Street, Belmont, Massachusetts 02178.
Page 698 Volume 5 Number 9
period. Of 537 p a t i e n t s r e q u i r i n g sutures, 90 (16.5%) h a d l a c e r a t i o n s of the feet or toes. A n o t h e r 52 p a t i e n t s h a d m i n o r s u r g e r y for e i t h e r incision and d r a i n a g e , or excision of a foreign body in the foot. Therefore, a total of 142 (2%) p a t i e n t s t r e a t e d in t h e e m e r g e n c y d e p a r t m e n t h a d foot problems for which local a n e s t h e s i a could m i n i m i z e t h e i r discomfort.
Advantages of Nerve Block Many physicians are unfamiliar with the techniques of n e r v e blocks in the foot. Yet, t h e y can produce excellent r e g i o n a l a n e s t h e s i a w i t h very little m o r b i d i t y a n d a significant increase in p a t i e n t comfort. Also, children seem to t o l e r a t e the nerve block procedure b e t t e r t h a n local infiltration. I n f i l t r a t i o n a n e s t h e s i a is comm o n l y e m p l o y e d for soft t i s s u e inj u r i e s of the foot b u t the injection can be painful, possibly due to distention of soft t i s s u e s p r o d u c e d by t h e a n e s t h e t i c solution. In t h e a u t h o r s ' experience, injections in the p l a n t a r
s u r f a c e , w h e r e t h e s k i n is b o u n d t i g h t l y to t h e u n d e r l y i n g fascia by connective t i s s u e septa t h a t l i m i t diffusion, are especially painful. A s p r e a d i n g agent, such as h y a l u r o n idase, promotes d i f f u s i o n and facilit a t e s t h e s p r e a d of t h e s o l u t i o n through a wider area, minimizing discomfort b u t s h o r t e n i n g the duration of anesthesia.l-3 Local anesthetics with vasoconstrictors, such as e p i n e p h r i n e , have been shown to i n h i b i t h e a l i n g in the a r e a of injury 4-s a n d to reduce resistance to infection locally, 7 especially in concentrations g r e a t e r t h a n l : 2 0 0 , 0 0 0 . e , s , s T h e r e is s o m e evidence that the anesthetics themselves i n t e r f e r e w i t h wound healing, though t h i s is Controversial.5,8, TM The c i r c u m f e r e n t i a l block h a s the disadv a n t a g e of m u l t i p l e n e e d l e punctures. F i n a l l y , all l a c e r a t i o n s within the sensory d i s t r i b u t i o n of the same n e r v e c a n be a n e s t h e t i z e d w i t h a single injection w h e n a n e r v e block is used.
NERVE BLOCK TECHNIQUE The c u t a n e o u s i n n e r v a t i o n of the foot is of p r i m a r y concern since the m a j o r i t y of i n j u r i e s r e q u i r i n g local a n e s t h e s i a i n v o l v e t h e soft t i s s u e s (Figure 1). The c u t a n e o u s nerve supply is not n e c e s s a r i l y f u r n i s h e d solely b y t h e s u p e r f i c i a l c u t a n e o u s nerves. The anterior tibial nerve (deep peroneal) supplies the l a t e r a l aspect of t h e g r e a t toe and the medial aspect of the second toe (Figure la). The posterior t i b i a l nerve a n d its
September 1976 , ~ P
the medial aspect of the foot and ankle). Lateral sural
2_ T h e m e d i a l dorsal c u t a n e o u s nerve.
Saphenous nerve
cutaneous nerve
Medial plantar n e r v e
Superficial Sural nerve
peroneal nerve
Lateral
Anterior tibial nerve
plantar _ nerve
a
I,,
A portion of the lateral aspect of the ankle, heel, a n d outer border of the foot and fifth toe are supplied by the sural nerve (Figure la).
Saphenous nerve
Sural nerve
Posterior
- tibial nerve
Medial plantar nerve
Fig. 1. a) Cutaneous innervation of the foot. (b) Cutaneous innervation of the plantar surface.
subdivisions supply most of the sole of the foot (Figure lb). In choosing local anesthetic agents (Table 1), w h e n postoperative pain is minimal, a short-acting anesthetic such as lidocaine or procaine m a y be used. W h e n pain is anticipated following i n s t r u m e n t a t i o n , d e b r i d e ment, or other emergency procedure, a longer a c t i n g a n e s t h e t i c such as bupivacaine hydrochloride t h a t can provide a n e s t h e s i a up to 70 hours ~ is desirable. In extensive lacerations, deep exp l o r a t o r y p r o c e d u r e s for f o r e i g n bodies, or severe s p r a i n s a n d fractures, a l o n g period of a n e s t h e s i a could provide the p a t i e n t with freedom from p a i n a n d help to avoid a pain-reflex spasm cycle. A n ancillary benefit of n e r v e block is t h e concomitant i n c r e a s e i n c i r c u l a t i o n in the a n e s t h e t i z e d area_ We b e l i e v e that the n e r v e block produces a temporary, local, '~chemica] sympathectomy" a n d , t h u s , i n c r e a s e s blood supply to the area. One of the authors (RKL) a n d Steinbergl2,13 believe the use of n e r v e blocks m a r k edly i m p r o v e s h e a l i n g of local circulatory problems and arterial insufficiency. The a d v a n t a g e s and disadvantages of the a d d i t i o n of a vas0constrictor to the anesthetic agents are well known.14-~s With the advent of the l o n g - a c t i n g a n e s t h e t i c s such as m e p i v a c a i n e a n d b u p i v a c a i n e , the c o n c o m i t a n t use of the epinePhrine is obviated. There is no evidence t h a t the longer acting drugs are a n y m o r e c y t o t o x i c t h a n t h e shorter acting ones in common use. 1
J~P
September 1976
3. The i n t e r m e d i a t e dorsal cutaneous nerve.
The g e n e r a l p r i n c i p l e s of n e r v e block injection t e c h n i q u e should be f o l l o w e d ( T a b l e 2)_ Blocks are classified according to the n a m e of the nerve block and/or the anatomic location at which the block is produced.
Anterior Ankle Block The n e r v e s p a s s i n g t h r o u g h the anterior aspect of the ankle into the foot i n c l u d e t h e t h r e e s u p e r f i c i a l nerves a n d the deeper anterior tibial nerve (deep peroneal nerve) (Figures 2 and 3). Innervation. The superficial nerves are (medially to laterally): 1. The saphenous nerve (supplying
A n a t o m i c v a r i a t i o n s . T h e anterior tibial nerve may vary in its relation to the m u s c u l u s extensor hallucis long~s and its tendon, 18 passing either l a t e r a l l y or m e d i a l l y to this structure (Figure 2). T e c h n i q u e . The p a t i e n t is placed in the supine position with a sandbag u n d e r the lower calf_ ~ E x t e n d the foot a n d a n k l e to k e e p t h e foot slightly extended. M a r k a line circumscribing the a n k l e approximately 1 cm above base of the medial malleolus. At a point on the line, j u s t m e d i a l to the extensor longus hallucis tendon, i n s e r t a 1'/2 in, 25 gauge needle at r i g h t angles pointed s l i g h t l y towards the fibula (Figure 3a). I n s e r t the needle u n t i l it touches t h e t i b i a a n d t h e n w i t h d r a w it s l i g h t l y . I n j e c t 4 or 5 cc of t h e anesthetic solution. Then redirect the needle l a t e r a l l y b e t w e e n the m u s c u l u s extensor digitorum longus and the tibia and inject a n additional 3 or 4 cc of anesthetic solution.
Table 1 COMPARISON OF LOCAL ANESTHETIC AGENTS*
Anesthetic Agent procaine HCl (Novocaine) (1%, 2%)
Concen- Relative tration potency 1% 1
Maximum dose (mg) 100
Onset time Duration (min) (min) 7 20
lidocaine HCl (Xylocaine) (1%, 2%)
1%
4
500
5
40
mepivacaine HCI (Carbocaine) (1%, 1.5%, 2%)
1%
4
500
4
100
prilocaine HCI (Citanest) (1%, 2%, 3%) bupivacaine HCI (Marcaine) (0.25%, 0.5%) tetracaine HCI (Pontocaine)~ (1%)
1%
4
600
4
100
0.25%1-
16
200
8
420
0.25%1-
16
100
7
135
* From Covino 11 1 These solutions contain epinephrine i :200,000 :l:*Not generally used for nerve blocks
Volume 5 Number 9 Page 699
Medial\
i
dorsal \ ' : " :i cutaneous I ":,': !77i:. nerve / ~:'. .' !i' "~ ,~'r "~__~. Interrnediate~i dorsal ~.;~/J/~.~'~L-~ cutaneous ~ , ! , ~ ' ~ ' ~
i
/ ,/ !t~ ~) Saphenous I nerve
nerve
~,~- ~ J ~-~% ~ Su;:/F ~ - -
Posterior tibial nerve
Table 2 G E N E R A L P R I N C I P L E S OF N E R V E BLOCK INJECTION TECHNIQUE
• A syringe as small as possible to deliver the required volume of anesthetic should be used; the larger the syringe, the greater the hydraulic pressure and, therefore, the more pain at injection. • Use needles of the smallest practical gauge and length. • Anesthetic solutions should be at room temperature before use - - cold solutions cause pain on injection. • Volume of anesthetic should be reduced in children and should be in proportion of the size of the anatomical part.
F i g . 2. Section through malleoli of left
ankle.
T h e s u p e r f i c i a l or c u t a n e o u s n e r v e s a r e now i n j e c t e d - b y w h a t Nott ~8 refers to as a "subcutaneous garter." The long 25 gauge needle is sufficiently flexible to a t t a i n a complete block of the saphenous and the m e d i a l c u t a n e o u s n e r v e s from t h e s a m e injection site by d i r e c t i n g the needle in a m e d i a l and l a t e r a l subc u t a n e o u s injection. The l a t e r a l injection should e x t e n d s u b c u t a n e o u s l y almost to the l a t e r a l malleolus. In a heavy ankle, these injections may h a v e to be m a d e from p o i n t s m o r e m e d i a l or l a t e r a l to a s s u r e t h i s
Nerve Blocks of the Foot Raymond K. Locke, DPM* Philadelphia, Pennsylvania Steven E. Locke, MDt Belmont, Massachusetts
E m e r g e n c y t r e a t m e n t o f f o o t i n j u r i e s c a n b e m a d e l e s s p a i n f u l b y reg i o n a l b l o c k a n e s t h e s i a . T h e r e is l i m i t e d m e d i c a l l i t e r a t u r e o n t h e s e techniques and many physicians, while familiar with regional anest h e s i a o f t h e u p p e r e x t r e m i t y , a r e n o t e x p e r i e n c e d w i t h n e r v e b l o c k s in t h e l o w e r e x t r e m i t y . I n f i l t r a t i o n a n e s t h e s i a of t h e p l a n t a r s t r u c t u r e s of the foot and toes can be very painful and may inhibit healing. Regional anesthesia avoids both of these problems and can prove effective and useful. This paper discusses the techniques and possible complications o f n e r v e b l o c k a n e s t h e s i a o f t h e foot.
Locke RK, Locke SE: Nerve blocks of the foot. JACEP 5:698-702, September 1976. anesthesia, regional, foot; blocks, ankle, a n t e r i o r . . , posterolateral . . . posterior tibial . . . toe; blocks, nerve; drug reactions, adverse; injuries, foot.
INTRODUCTION Patients with foot injuries are most common during summer and vacation periods, in resort or recreat i o n a r e a s , a n d in w a r m c l i m a t e s where people go b a r e f o o t . , A t Tobey Hospital, a s m a l l c o m m u n i t y hospit a l in W a r e h a m , M a s s a c h u s e t t s , a New England coastal resort town n e a r Cape Cod, a total of 7,627 pat i e n t s were e x a m i n e d and t r e a t e d by e m e r g e n c y p h y s i c i a n s from J u l y 1, 1973 to S e p t e m b e r 30, 1973, t h e h e i g h t of t h e s u m m e r v a c a t i o n From the D e p a r t m e n t of Podiatric Surgery,* Riverdell Hospital, Oradelli New Jersey; P e n n s y l v a n i a College of Podiatric Medicine,* Philadelphia, Pennsylvania; and Tobey Hospital,t Wareham, Massachusetts, Department of Psychiatry, Harvard Medical School. McLean Hospital, Belmont, Massachusetts. This paper was supported in part by a grant from Winthrop Laboratories, New York, New York. Address for reprints: Steven E. Locke, MD, McLean Hospital, 115 Mill Street, Belmont, Massachusetts 02178.
Page 698 Volume 5 Number 9
period. Of 537 p a t i e n t s r e q u i r i n g sutures, 90 (16.5%) h a d l a c e r a t i o n s of the feet or toes. A n o t h e r 52 p a t i e n t s h a d m i n o r s u r g e r y for e i t h e r incision and d r a i n a g e , or excision of a foreign body in the foot. Therefore, a total of 142 (2%) p a t i e n t s t r e a t e d in t h e e m e r g e n c y d e p a r t m e n t h a d foot problems for which local a n e s t h e s i a could m i n i m i z e t h e i r discomfort.
Advantages of Nerve Block Many physicians are unfamiliar with the techniques of n e r v e blocks in the foot. Yet, t h e y can produce excellent r e g i o n a l a n e s t h e s i a w i t h very little m o r b i d i t y a n d a significant increase in p a t i e n t comfort. Also, children seem to t o l e r a t e the nerve block procedure b e t t e r t h a n local infiltration. I n f i l t r a t i o n a n e s t h e s i a is comm o n l y e m p l o y e d for soft t i s s u e inj u r i e s of the foot b u t the injection can be painful, possibly due to distention of soft t i s s u e s p r o d u c e d by t h e a n e s t h e t i c solution. In t h e a u t h o r s ' experience, injections in the p l a n t a r
s u r f a c e , w h e r e t h e s k i n is b o u n d t i g h t l y to t h e u n d e r l y i n g fascia by connective t i s s u e septa t h a t l i m i t diffusion, are especially painful. A s p r e a d i n g agent, such as h y a l u r o n idase, promotes d i f f u s i o n and facilit a t e s t h e s p r e a d of t h e s o l u t i o n through a wider area, minimizing discomfort b u t s h o r t e n i n g the duration of anesthesia.l-3 Local anesthetics with vasoconstrictors, such as e p i n e p h r i n e , have been shown to i n h i b i t h e a l i n g in the a r e a of injury 4-s a n d to reduce resistance to infection locally, 7 especially in concentrations g r e a t e r t h a n l : 2 0 0 , 0 0 0 . e , s , s T h e r e is s o m e evidence that the anesthetics themselves i n t e r f e r e w i t h wound healing, though t h i s is Controversial.5,8, TM The c i r c u m f e r e n t i a l block h a s the disadv a n t a g e of m u l t i p l e n e e d l e punctures. F i n a l l y , all l a c e r a t i o n s within the sensory d i s t r i b u t i o n of the same n e r v e c a n be a n e s t h e t i z e d w i t h a single injection w h e n a n e r v e block is used.
NERVE BLOCK TECHNIQUE The c u t a n e o u s i n n e r v a t i o n of the foot is of p r i m a r y concern since the m a j o r i t y of i n j u r i e s r e q u i r i n g local a n e s t h e s i a i n v o l v e t h e soft t i s s u e s (Figure 1). The c u t a n e o u s nerve supply is not n e c e s s a r i l y f u r n i s h e d solely b y t h e s u p e r f i c i a l c u t a n e o u s nerves. The anterior tibial nerve (deep peroneal) supplies the l a t e r a l aspect of t h e g r e a t toe and the medial aspect of the second toe (Figure la). The posterior t i b i a l nerve a n d its
September 1976 , ~ P
the medial aspect of the foot and ankle). Lateral sural
2_ T h e m e d i a l dorsal c u t a n e o u s nerve.
Saphenous nerve
cutaneous nerve
Medial plantar n e r v e
Superficial Sural nerve
peroneal nerve
Lateral
Anterior tibial nerve
plantar _ nerve
a
I,,
A portion of the lateral aspect of the ankle, heel, a n d outer border of the foot and fifth toe are supplied by the sural nerve (Figure la).
Saphenous nerve
Sural nerve
Posterior
- tibial nerve
Medial plantar nerve
Fig. 1. a) Cutaneous innervation of the foot. (b) Cutaneous innervation of the plantar surface.
subdivisions supply most of the sole of the foot (Figure lb). In choosing local anesthetic agents (Table 1), w h e n postoperative pain is minimal, a short-acting anesthetic such as lidocaine or procaine m a y be used. W h e n pain is anticipated following i n s t r u m e n t a t i o n , d e b r i d e ment, or other emergency procedure, a longer a c t i n g a n e s t h e t i c such as bupivacaine hydrochloride t h a t can provide a n e s t h e s i a up to 70 hours ~ is desirable. In extensive lacerations, deep exp l o r a t o r y p r o c e d u r e s for f o r e i g n bodies, or severe s p r a i n s a n d fractures, a l o n g period of a n e s t h e s i a could provide the p a t i e n t with freedom from p a i n a n d help to avoid a pain-reflex spasm cycle. A n ancillary benefit of n e r v e block is t h e concomitant i n c r e a s e i n c i r c u l a t i o n in the a n e s t h e t i z e d area_ We b e l i e v e that the n e r v e block produces a temporary, local, '~chemica] sympathectomy" a n d , t h u s , i n c r e a s e s blood supply to the area. One of the authors (RKL) a n d Steinbergl2,13 believe the use of n e r v e blocks m a r k edly i m p r o v e s h e a l i n g of local circulatory problems and arterial insufficiency. The a d v a n t a g e s and disadvantages of the a d d i t i o n of a vas0constrictor to the anesthetic agents are well known.14-~s With the advent of the l o n g - a c t i n g a n e s t h e t i c s such as m e p i v a c a i n e a n d b u p i v a c a i n e , the c o n c o m i t a n t use of the epinePhrine is obviated. There is no evidence t h a t the longer acting drugs are a n y m o r e c y t o t o x i c t h a n t h e shorter acting ones in common use. 1
J~P
September 1976
3. The i n t e r m e d i a t e dorsal cutaneous nerve.
The g e n e r a l p r i n c i p l e s of n e r v e block injection t e c h n i q u e should be f o l l o w e d ( T a b l e 2)_ Blocks are classified according to the n a m e of the nerve block and/or the anatomic location at which the block is produced.
Anterior Ankle Block The n e r v e s p a s s i n g t h r o u g h the anterior aspect of the ankle into the foot i n c l u d e t h e t h r e e s u p e r f i c i a l nerves a n d the deeper anterior tibial nerve (deep peroneal nerve) (Figures 2 and 3). Innervation. The superficial nerves are (medially to laterally): 1. The saphenous nerve (supplying
A n a t o m i c v a r i a t i o n s . T h e anterior tibial nerve may vary in its relation to the m u s c u l u s extensor hallucis long~s and its tendon, 18 passing either l a t e r a l l y or m e d i a l l y to this structure (Figure 2). T e c h n i q u e . The p a t i e n t is placed in the supine position with a sandbag u n d e r the lower calf_ ~ E x t e n d the foot a n d a n k l e to k e e p t h e foot slightly extended. M a r k a line circumscribing the a n k l e approximately 1 cm above base of the medial malleolus. At a point on the line, j u s t m e d i a l to the extensor longus hallucis tendon, i n s e r t a 1'/2 in, 25 gauge needle at r i g h t angles pointed s l i g h t l y towards the fibula (Figure 3a). I n s e r t the needle u n t i l it touches t h e t i b i a a n d t h e n w i t h d r a w it s l i g h t l y . I n j e c t 4 or 5 cc of t h e anesthetic solution. Then redirect the needle l a t e r a l l y b e t w e e n the m u s c u l u s extensor digitorum longus and the tibia and inject a n additional 3 or 4 cc of anesthetic solution.
Table 1 COMPARISON OF LOCAL ANESTHETIC AGENTS*
Anesthetic Agent procaine HCl (Novocaine) (1%, 2%)
Concen- Relative tration potency 1% 1
Maximum dose (mg) 100
Onset time Duration (min) (min) 7 20
lidocaine HCl (Xylocaine) (1%, 2%)
1%
4
500
5
40
mepivacaine HCI (Carbocaine) (1%, 1.5%, 2%)
1%
4
500
4
100
prilocaine HCI (Citanest) (1%, 2%, 3%) bupivacaine HCI (Marcaine) (0.25%, 0.5%) tetracaine HCI (Pontocaine)~ (1%)
1%
4
600
4
100
0.25%1-
16
200
8
420
0.25%1-
16
100
7
135
* From Covino 11 1 These solutions contain epinephrine i :200,000 :l:*Not generally used for nerve blocks
Volume 5 Number 9 Page 699
Medial\
i
dorsal \ ' : " :i cutaneous I ":,': !77i:. nerve / ~:'. .' !i' "~ ,~'r "~__~. Interrnediate~i dorsal ~.;~/J/~.~'~L-~ cutaneous ~ , ! , ~ ' ~ ' ~
i
/ ,/ !t~ ~) Saphenous I nerve
nerve
~,~- ~ J ~-~% ~ Su;:/F ~ - -
Posterior tibial nerve
Table 2 G E N E R A L P R I N C I P L E S OF N E R V E BLOCK INJECTION TECHNIQUE
• A syringe as small as possible to deliver the required volume of anesthetic should be used; the larger the syringe, the greater the hydraulic pressure and, therefore, the more pain at injection. • Use needles of the smallest practical gauge and length. • Anesthetic solutions should be at room temperature before use - - cold solutions cause pain on injection. • Volume of anesthetic should be reduced in children and should be in proportion of the size of the anatomical part.
F i g . 2. Section through malleoli of left
ankle.
T h e s u p e r f i c i a l or c u t a n e o u s n e r v e s a r e now i n j e c t e d - b y w h a t Nott ~8 refers to as a "subcutaneous garter." The long 25 gauge needle is sufficiently flexible to a t t a i n a complete block of the saphenous and the m e d i a l c u t a n e o u s n e r v e s from t h e s a m e injection site by d i r e c t i n g the needle in a m e d i a l and l a t e r a l subc u t a n e o u s injection. The l a t e r a l injection should e x t e n d s u b c u t a n e o u s l y almost to the l a t e r a l malleolus. In a heavy ankle, these injections may h a v e to be m a d e from p o i n t s m o r e m e d i a l or l a t e r a l to a s s u r e t h i s
